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  • spring 跟 诠释及区别

    <context:annotation-config> 和 <context:component-scan>的区别

    Difference between <context:annotation-config> vs <context:component-scan>

    <context:annotation-config> 是用于激活那些已经在spring容器里注册过的bean（无论是通过xml的方式还是通过package sanning的方式）上面的注解，是一个注解处理工具。

    <context:component-scan>除了具有<context:annotation-config>的功能之外，<context:component-scan>还可以在指定的package下扫描以及注册javabean 。

     

    下面我们通过例子来详细查看他们的区别，

    有三个class   A,B,C,并且B,C的对象被注入到A中.

     

    [java] view plaincopy在CODE上查看代码片派生到我的代码片
    1. package com.xxx;  
    2. public class B {  
    3.   public B() {  
    4.     System.out.println("creating bean B: " + this);  
    5.   }  
    6. }  
    7.   
    8. package com.xxx;  
    9. public class C {  
    10.   public C() {  
    11.     System.out.println("creating bean C: " + this);  
    12.   }  
    13. }  
    14.   
    15. package com.yyy;  
    16. import com.xxx.B;  
    17. import com.xxx.C;  
    18. public class A {   
    19.   private B bbb;  
    20.   private C ccc;  
    21.   public A() {  
    22.     System.out.println("creating bean A: " + this);  
    23.   }  
    24.   public void setBbb(B bbb) {  
    25.     System.out.println("setting A.bbb with " + bbb);  
    26.     this.bbb = bbb;  
    27.   }  
    28.   public void setCcc(C ccc) {  
    29.     System.out.println("setting A.ccc with " + ccc);  
    30.     this.ccc = ccc;   
    31.   }  
    32. }  

     

     

    在applicationContext.xml中加入下面的配置 :

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.B"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
<</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"cBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.C"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"aBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.yyy.A"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
  <</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">property name</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bbb"</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> ref</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bBean"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
  </span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">property name</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"ccc"</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> ref</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"cBean"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
</</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">></span></code>

     

    加载applicationContext.xml配置文件，将得到下面的结果:

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@c2ff5
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@1e8a1f6
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@1e152c5
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@c2ff5
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@1e8a1f6</span></code>

     

    OK, 这个结果没什么好说的，就是完全通过xml的方式，不过太过时了，下面通过注解的方式来简化我们的xml配置文件

    首先，我们使用autowire的方式将对象bbb和ccc注入到A中：

     

     

    [java] view plaincopy在CODE上查看代码片派生到我的代码片
    1. package com.yyy;  
    2. import org.springframework.beans.factory.annotation.Autowired;  
    3. import com.xxx.B;  
    4. import com.xxx.C;  
    5. public class A {   
    6.   private B bbb;  
    7.   private C ccc;  
    8.   public A() {  
    9.     System.out.println("creating bean A: " + this);  
    10.   }  
    11.   @Autowired  
    12.   public void setBbb(B bbb) {  
    13.     System.out.println("setting A.bbb with " + bbb);  
    14.     this.bbb = bbb;  
    15.   }  
    16.   @Autowired  
    17.   public void setCcc(C ccc) {  
    18.     System.out.println("setting A.ccc with " + ccc);  
    19.     this.ccc = ccc;  
    20.   }  
    21. }  
     

     

    然后，我们就可以从applicationContext.xml中移除下面的配置

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">property name</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bbb"</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> ref</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bBean"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
<</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">property name</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"ccc"</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> ref</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"cBean"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></code>

     

    移除之后，我们的applicationContext.xml配置文件就简化为下面的样子了

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.B"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"cBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.C"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"aBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.yyy.A"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></code>

     

    当我们加载applicationContext.xml配置文件之后，将得到下面的结果：

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@5e5a50
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@54a328
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@a3d4cf</span></code>

     

    OK, 结果是错误的的，究竟是因为什么呢？为什么我们的属性没有被注入进去呢？

    是因为注解本身并不能够做任何事情，它们只是最基本的组成部分，我们需要能够处理这些注解的处理工具来处理这些注解

    这就是<context:annotation-config> 所做的事情

    我们将applicationContext.xml配置文件作如下修改：

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span style="color: rgb(255, 0, 0);"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">annotation</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">config </span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
<span style="color: rgb(255, 0, 0);"><</span></span><span style="color: rgb(255, 0, 0);"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bBean"</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.B"</span></span><span style="color: rgb(255, 0, 0);"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"cBean"</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.C"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
<span style="color: rgb(255, 0, 0);"><</span></span><span style="color: rgb(255, 0, 0);"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"aBean"</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.yyy.A"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></span></code>

     

    当我们加载applicationContext.xml配置文件之后，将得到下面的结果：

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@15663a2
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@cd5f8b
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@157aa53
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@15663a2
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@cd5f8b</span></code>

     

    OK, 结果正确了。


    下面演示<context:annotation-config> 跟 <context:component-scan>区别：

    但是如果我们将代码作如下修改：

     

     

    [java] view plaincopy在CODE上查看代码片派生到我的代码片
    1. package com.xxx;  
    2. import org.springframework.stereotype.Component;  
    3. @Component  
    4. public class B {  
    5.   public B() {  
    6.     System.out.println("creating bean B: " + this);  
    7.   }  
    8. }  
    9.   
    10. package com.xxx;  
    11. import org.springframework.stereotype.Component;  
    12. @Component  
    13. public class C {  
    14.   public C() {  
    15.     System.out.println("creating bean C: " + this);  
    16.   }  
    17. }  
    18.   
    19. package com.yyy;  
    20. import org.springframework.beans.factory.annotation.Autowired;  
    21. import org.springframework.stereotype.Component;  
    22. import com.xxx.B;  
    23. import com.xxx.C;  
    24. @Component  
    25. public class A {   
    26.   private B bbb;  
    27.   private C ccc;  
    28.   public A() {  
    29.     System.out.println("creating bean A: " + this);  
    30.   }  
    31.   @Autowired  
    32.   public void setBbb(B bbb) {  
    33.     System.out.println("setting A.bbb with " + bbb);  
    34.     this.bbb = bbb;  
    35.   }  
    36.   @Autowired  
    37.   public void setCcc(C ccc) {  
    38.     System.out.println("setting A.ccc with " + ccc);  
    39.     this.ccc = ccc;  
    40.   }  
    41. }  
     

     

     

    applicationContext.xml配置文件修改为：

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">annotation</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">config </span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></code>

     

    当我们加载applicationContext.xml配置文件之后，却没有任何输出，这是为什么呢？

    那是因为<context:annotation-config />仅能够在已经在已经注册过的bean上面起作用。

    对于没有在spring容器中注册的bean，它并不能执行任何操作。

    但是不用担心，<context:component-scan>除了具有<context:annotation-config />的功能之外，还具有自动将带有@component,@service,@Repository等注解的对象注册到spring容器中的功能。

    我们将applicationContext.xml配置文件作如下修改：

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></code>

     

    当我们加载applicationContext.xml的时候，会得到下面的结果：

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@1be0f0a
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@80d1ff</span></code>

     

    这是什么原因呢？

    是因为我们仅仅扫描了com.xxx包及其子包的类，而class  A是在com.yyy包下，所以就扫描不到了

    下面我们在applicationContext.xml中把com.yyy也加入进来：

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span style="color: rgb(255, 0, 0);"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx"</span></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><span style="color: rgb(255, 0, 0);">/>

</span></span></code><span style="color: rgb(255, 0, 0);"><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">"com.xxx,com.yyy"</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">/></span></span>
    然后加载applicationContext.xml就会得到下面的结果：<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"></code>
    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@cd5f8b
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@15ac3c9
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@ec4a87
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@cd5f8b
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@15ac3c9</span></code>

     

    哇，结果正确啦 ！

    回头看下我们的applicationContext.xml文件，已经简化为：

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>

</span></code><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="font-family: 'Courier New', Courier, monospace; color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="font-family: 'Courier New', Courier, monospace; color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">"com.xxx,com.yyy"</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">/></span>

     

    了。

     

    那如果我们在applicationContext.xml手动加上下面的配置，也就是说既在applicationContext.xml中手动的注册了A的实例对象，同时，通过component-scan去扫描并注册B,C的对象

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span style="color: rgb(255, 0, 0);"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx"</span></span><span style="color: rgb(255, 0, 0);"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"aBean"</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.yyy.A"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></span></code>

     

    结果仍是正确的:

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@1d64c37
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87</span></code>

     

    虽然class  A并不是通过扫描的方式注册到容器中的 ，但是<context:component-scan> 所产生的的处理那些注解的处理器工具，会处理所有绑定到容器上面的bean，不管是通过xml手动注册的还是通过scanning扫描注册的。

    那么，如果我们通过下面的方式呢？我们既配置了<context:annotation-config />，又配置了<context:component-scan base-package="com.xxx" />，它们都具有处理在容器中注册的bean里面的注解的功能。会不会出现重复注入的情况呢？

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">annotation</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">config </span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"aBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.yyy.A"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></code>

     

    不用担心，不会出现的：

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@1d64c37
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87</span></code>

     

    因为<context:annotation-config />和 <context:component-scan>同时存在的时候，前者会被忽略。也就是那些@autowire，@resource等注入注解只会被注入一次

    哪怕是你手动的注册了多个处理器，spring仍然只会处理一次：

     

    [xml] view plaincopy在CODE上查看代码片派生到我的代码片
    1. <context:annotation-config />  
    2. <context:component-scan base-package="com.xxx" />  
    3. <bean id="aBean" class="com.yyy.A" />  
    4. <bean id="bla" class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />  
    5. <bean id="bla1" class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />  
    6. <bean id="bla2" class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />  
    7. <bean id="bla3" class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />  

     

     

    结果仍是正确的：

     

    <code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@25d2b2
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87</span></code>
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  • 原文地址：https://www.cnblogs.com/hzcya1995/p/13318018.html
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