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Spring特性--DI

DI：Dependency Injection（依赖注入），通俗的讲就是一种通过xml配置文件，为交给sping容器的对象初始化参数。又称做控制反转:Inversion of Control(IoC)

依赖注入主要分为四种形式：

|-：基于构造方法的依赖注入

|-：基于setter方法的依赖注入

|-：基于工厂的注入　

|-：基于泛型的注入

基于构造方法的依赖注入又可以分为以下几种：

·复杂数据类型：

·简单数据类型：

|- 基于属性类型(type)

|-基于索引(index)

|-基于参数名称(name)

复杂数据类型实例

  1 package com.fuwh.spring;
  2  
  3 
  4 /*
  5  * POJO类
  6  */
  7 public class Clazz {
  8 
  9 private String name;
 10 private int grade;
 11 public String getName() {
 12 return name;
 13 }
 14 public void setName(String name) {
 15 this.name = name;
 16 }
 17 public int getGrade() {
 18 return grade;
 19 }
 20 public void setGrade(int grade) {
 21 this.grade = grade;
 22 }
 23 
 24 }
 25 package com.fuwh.spring;
 26 /*
 27  * POJO类
 28  */
 29 public class Lesson {
 30 
 31 private String name;
 32 private int score;
 33 public String getName() {
 34 return name;
 35 }
 36 public void setName(String name) {
 37 this.name = name;
 38 }
 39 public int getScore() {
 40 return score;
 41 }
 42 public void setScore(int score) {
 43 this.score = score;
 44 }
 45 
 46 }
 47 package com.fuwh.spring;
 48 
 49 public class Student {
 50 
 51 private Clazz clazz;
 52 private Lesson lesson;
 53 
 54 public Student(Clazz clazz, Lesson lesson) {
 55 this.clazz = clazz;
 56 this.lesson = lesson;
 57 }
 58 
 59 @Override
 60 public String toString() {
 61 return "Student [clazz=" + clazz.getGrade()+clazz.getName() + ", lesson=" + lesson.getName()+","+lesson.getScore() + "学分]";
 62 }
 63 
 64 }
 65  
 66 
 67 
 68 <?xml version="1.0" encoding="UTF-8"?>
 69  
 70 
 71 <beans xmlns="http://www.springframework.org/schema/beans"
 72     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 73     xsi:schemaLocation="http://www.springframework.org/schema/beans
 74         http://www.springframework.org/schema/beans/spring-beans.xsd">
 75 
 76     <!-- 配置文件 -->
 77 
 78 <bean id="student" class="com.fuwh.spring.Student" lazy-init="default">
 79 <constructor-arg ref="clazz"/>
 80 <constructor-arg ref="lesson"/>
 81 </bean>
 82 
 83 
 84 <bean id="clazz" class="com.fuwh.spring.Clazz">
 85 <property name="name" value="信本"/>
 86 <property name="grade" value="08"/>
 87 </bean>
 88 <bean id="lesson" class="com.fuwh.spring.Lesson">
 89 <property name="name" value="java"/>
 90 <property name="score" value="4"/>
 91 </bean>
 92 </beans>
 93  
 94 
 95 
 96 package com.fuwh.spring;
 97  
 98 
 99 
100 import org.springframework.context.ApplicationContext;
101 import org.springframework.context.support.ClassPathXmlApplicationContext;
102 
103 public class Spring01 {
104 
105 public static void main(String[] args) {
106 /*
107 * 测试类
108 */
109 ApplicationContext ac=new ClassPathXmlApplicationContext("bean.xml");
110 System.out.println(ac.getBean("student",Student.class));
111 }
112 }

基于属性类型(type) 实例：

 1 package com.fuwh.spring;
 2 /*
 3  * POJO类
 4  */
 5 public class Clazz {
 6 
 7 private String name;
 8 private int grade;
 9 
10 public Clazz(String name, int grade) {
11 super();
12 this.name = name;
13 this.grade = grade;
14 }
15 @Override
16 public String toString() {
17 return "Student [name=" + name + ", grade=" + grade + "]";
18 }
19 
20 }

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- spring配置文件 -->
<bean id="clazz" class="com.fuwh.spring.Clazz" lazy-init="default">
<constructor-arg type="String" value="信息与计算科学"/>
<constructor-arg type="int" value="08"/>
</bean>
</beans>

package com.fuwh.spring;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Spring01 {

public static void main(String[] args) {
/*
* 测试类
*/
//ApplicationContext ac=new ClassPathXmlApplicationContext("bean.xml");
//ApplicationContext ac=new ClassPathXmlApplicationContext(new String[]{"beanStudent.xml","beanClazz.xml"});
//ApplicationContext ac=new ClassPathXmlApplicationContext("beanStudent.xml");
//System.out.println(ac.getBean("student"));
ApplicationContext ac=new ClassPathXmlApplicationContext("beanClazz.xml");
System.out.println(ac.getBean("clazz",Clazz.class));
}
}

基于索引（index）实例：

※需要注意的是，索引是从“0”开始

<?xml version="1.0" encoding="UTF-8"?>
 

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- spring配置文件 -->
<bean id="clazz" class="com.fuwh.spring.Clazz" lazy-init="default">
<constructor-arg index="0" value="信息与计算科学"/>
<constructor-arg index="1" value="08"/>
</bean>
</beans>

基于参数名称（name）实例:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- spring配置文件 -->
<bean id="clazz" class="com.fuwh.spring.Clazz" lazy-init="default">
<constructor-arg name="name" value="信息与计算科学"/>
<constructor-arg name="grade" index="1" value="08"/>
</bean>
</beans>

基于setter方法的依赖注入

package com.fuwh.spring;
 

/*
 * POJO类
 */
public class Lesson {

private String name;
private int score;

public void setName(String name) {
System.out.println("name parameter is injected");
this.name = name;
}

public void setScore(int score) {
System.out.println("score parameter is injected");
this.score = score;
}

@Override
public String toString() {
return "Lesson [name=" + name + ", score=" + score + "学分]";
}

}

<?xml version="1.0" encoding="UTF-8"?>
 

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- spring配置文件 -->
<bean id="lesson" class="com.fuwh.spring.Lesson" lazy-init="default"
p:name="php"
p:score="2"/>
</beans>

package com.fuwh.spring;
 


import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Spring01 {

public static void main(String[] args) {
/*
* 测试类
*/
ApplicationContext ac=new ClassPathXmlApplicationContext("beanLesson.xml");
System.out.println(ac.getBean("lesson",Lesson.class));
}
}

在注入的时候，使用以上两种方式都是可以的，但是在以下一种情况下，只能使用setter的方式注入

Class A的构造方法中需要Class B的实例， Class B的构造方法中又需要Class A的实例，

这时候就会报BeanCurrentlyInCreationException的exception.

级联属性注入

 1 package com.fuwh.test;
 2 
 3 public class People {
 4 
 5     public int id;
 6     public String name;
 7     public int age;
 8     
 9     public Dog dog=new Dog();
10 
11     public int getId() {
12         return id;
13     }
14 
15     public void setId(int id) {
16         this.id = id;
17     }
18 
19     public String getName() {
20         return name;
21     }
22 
23     public void setName(String name) {
24         this.name = name;
25     }
26 
27     public int getAge() {
28         return age;
29     }
30 
31     public void setAge(int age) {
32         this.age = age;
33     }
34 
35     public Dog getDog() {
36         return dog;
37     }
38 
39     public void setDog(Dog dog) {
40         this.dog = dog;
41     }
42 
43     @Override
44     public String toString() {
45         return "People [id=" + id + ", name=" + name + ", age=" + age + ", dog=" + dog + "]";
46     }
47     
48     
49     
50 }

 1 package com.fuwh.test;
 2 
 3 public class Dog {
 4     
 5     public int id;
 6     public String name;
 7     public int age;
 8     public int getId() {
 9         return id;
10     }
11     public void setId(int id) {
12         this.id = id;
13     }
14     public String getName() {
15         return name;
16     }
17     public void setName(String name) {
18         this.name = name;
19     }
20     public int getAge() {
21         return age;
22     }
23     public void setAge(int age) {
24         this.age = age;
25     }
26     @Override
27     public String toString() {
28         return "Dog [id=" + id + ", name=" + name + ", age=" + age + "]";
29     }
30     
31     
32 }

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xsi:schemaLocation="http://www.springframework.org/schema/beans
 5         http://www.springframework.org/schema/beans/spring-beans.xsd">
 6 
 7     <bean id="people" class="com.fuwh.test.People">
 8         <property name="id" value="1"></property>
 9         <property name="name" value="laofu"></property>
10         <property name="age" value="27"></property>
11     
12     <!-- dog就是属于级联的初始化 -->
13         <property name="dog.id" value="12"></property>
14         <property name="dog.name" value="wangcai"></property>
15         <property name="dog.age" value="11"></property>
16     </bean>
17 
18     
19 
20 </beans>

最后，使用junit4进行测试

 1 package com.fuwh.test;
 2 
 3 
 4 import org.junit.Before;
 5 import org.springframework.context.ApplicationContext;
 6 import org.springframework.context.support.ClassPathXmlApplicationContext;
 7 
 8 public class Test {
 9 
10     private ApplicationContext ac;
11     
12 
13     @Before
14     public void setUp() throws Exception {
15         ac=new ClassPathXmlApplicationContext("beans.xml");
16     }
17 
18     @org.junit.Test
19     public void test() {
20         People people =(People)ac.getBean("people");
21         System.out.println(people);
22     }
23 
24 }

注入集合变量

List

 1 package com.fuwh.test;
 2 
 3 import java.util.ArrayList;
 4 import java.util.List;
 5 
 6 public class People {
 7 
 8     public int id;
 9     public String name;
10     public int age;
11     
12     public List<String> nameList=new ArrayList<String>();
13 
14     
15     
16     public List<String> getNameList() {
17         return nameList;
18     }
19 
20     public void setNameList(List<String> nameList) {
21         this.nameList = nameList;
22     }
23 
24     public int getId() {
25         return id;
26     }
27 
28     public void setId(int id) {
29         this.id = id;
30     }
31 
32     public String getName() {
33         return name;
34     }
35 
36     public void setName(String name) {
37         this.name = name;
38     }
39 
40     public int getAge() {
41         return age;
42     }
43 
44     public void setAge(int age) {
45         this.age = age;
46     }
47 
48     @Override
49     public String toString() {
50         return "People [id=" + id + ", name=" + name + ", age=" + age + ", nameList=" + nameList + "]";
51     }
52 
53     
54     
55     
56 }

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xsi:schemaLocation="http://www.springframework.org/schema/beans
 5         http://www.springframework.org/schema/beans/spring-beans.xsd">
 6 
 7     <bean id="people" class="com.fuwh.test.People">
 8         <property name="id" value="1"></property>
 9         <property name="name" value="laofu"></property>
10         <property name="age" value="27"></property>
11     
12         <property name="nameList">
13             <list>
14                 <value>唱歌</value>
15                 <value>跳舞</value>
16                 <value>编程</value>
17             </list>
18         </property>
19     </bean>
20 
21     
22 
23 </beans>

 1 package com.fuwh.test;
 2 
 3 
 4 import org.junit.Before;
 5 import org.springframework.context.ApplicationContext;
 6 import org.springframework.context.support.ClassPathXmlApplicationContext;
 7 
 8 public class Test {
 9 
10     private ApplicationContext ac;
11     
12 
13     @Before
14     public void setUp() throws Exception {
15         ac=new ClassPathXmlApplicationContext("beans.xml");
16     }
17 
18     @org.junit.Test
19     public void test() {
20         People people =(People)ac.getBean("people");
21         
22         System.out.println(people);
23     }
24 
25 }

map

 1 package com.fuwh.test;
 2 
 3 import java.util.HashMap;
 4 import java.util.Map;
 5 
 6 public class People {
 7 
 8     public int id;
 9     public String name;
10     public int age;
11     
12     public Map<String,String> nameMap=new HashMap<String,String>();
13 
14     public Map<String, String> getNameMap() {
15         return nameMap;
16     }
17 
18     public void setNameMap(Map<String, String> nameMap) {
19         this.nameMap = nameMap;
20     }
21 
22     public int getId() {
23         return id;
24     }
25 
26     public void setId(int id) {
27         this.id = id;
28     }
29 
30     public String getName() {
31         return name;
32     }
33 
34     public void setName(String name) {
35         this.name = name;
36     }
37 
38     public int getAge() {
39         return age;
40     }
41 
42     public void setAge(int age) {
43         this.age = age;
44     }
45 
46     @Override
47     public String toString() {
48         return "People [id=" + id + ", name=" + name + ", age=" + age + ", nameMap=" + nameMap + "]";
49     }
50 
51 }

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xsi:schemaLocation="http://www.springframework.org/schema/beans
 5         http://www.springframework.org/schema/beans/spring-beans.xsd">
 6 
 7     <bean id="people" class="com.fuwh.test.People">
 8         <property name="id" value="1"></property>
 9         <property name="name" value="laofu"></property>
10         <property name="age" value="27"></property>
11     
12         <property name="nameMap">
13             <map>
14                 <entry>
15                     <key><value>zhangsan</value></key>
16                     <value>张三</value>
17                 </entry>
18                 <entry>
19                     <key><value>lisi</value></key>
20                     <value>李四</value>
21                 </entry>
22             </map>
23         </property>
24     </bean>
25 
26     
27 
28 </beans>

 1 package com.fuwh.test;
 2 
 3 
 4 import org.junit.Before;
 5 import org.springframework.context.ApplicationContext;
 6 import org.springframework.context.support.ClassPathXmlApplicationContext;
 7 
 8 public class Test {
 9 
10     private ApplicationContext ac;
11     
12 
13     @Before
14     public void setUp() throws Exception {
15         ac=new ClassPathXmlApplicationContext("beans.xml");
16     }
17 
18     @org.junit.Test
19     public void test() {
20         People people =(People)ac.getBean("people");
21         
22         System.out.println(people);
23     }
24 
25 }

注入属性

 1 package com.fuwh.test;
 2 
 3 import java.util.Properties;
 4 
 5 public class People {
 6 
 7     private int id;
 8     private String name;
 9     private int age;
10     
11     private Properties address=new Properties();
12 
13     public Properties getAddress() {
14         return address;
15     }
16 
17     public void setAddress(Properties address) {
18         this.address = address;
19     }
20 
21     public int getId() {
22         return id;
23     }
24 
25     public void setId(int id) {
26         this.id = id;
27     }
28 
29     public String getName() {
30         return name;
31     }
32 
33     public void setName(String name) {
34         this.name = name;
35     }
36 
37     public int getAge() {
38         return age;
39     }
40 
41     public void setAge(int age) {
42         this.age = age;
43     }
44 
45     @Override
46     public String toString() {
47         return "People [id=" + id + ", name=" + name + ", age=" + age + ", address=" + address + "]";
48     }
49 
50 }

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xsi:schemaLocation="http://www.springframework.org/schema/beans
 5         http://www.springframework.org/schema/beans/spring-beans.xsd">
 6 
 7     <bean id="people" class="com.fuwh.test.People">
 8         <property name="id" value="1"></property>
 9         <property name="name" value="laofu"></property>
10         <property name="age" value="27"></property>
11     
12         <property name="address">
13             <props>
14                 <prop key="sheng">shanghai</prop>
15                 <prop key="shi">pudong</prop>
16             </props>
17         </property>
18     </bean>
19 
20     
21 
22 </beans>

 1 package com.fuwh.test;
 2 
 3 
 4 import org.junit.Before;
 5 import org.springframework.context.ApplicationContext;
 6 import org.springframework.context.support.ClassPathXmlApplicationContext;
 7 
 8 public class Test {
 9 
10     private ApplicationContext ac;
11     
12 
13     @Before
14     public void setUp() throws Exception {
15         ac=new ClassPathXmlApplicationContext("beans.xml");
16     }
17 
18     @org.junit.Test
19     public void test() {
20         People people =(People)ac.getBean("people");
21         
22         System.out.println(people);
23     }
24 
25 }

bean的自动装配

　　bean的自动装配总共分为四种方式:

no	(Default) No autowiring. Bean references must be defined via a `ref` element. Changing the default setting is not recommended for larger deployments, because specifying collaborators explicitly gives greater control and clarity. To some extent, it documents the structure of a system.
byName	Autowiring by property name. Spring looks for a bean with the same name as the property that needs to be autowired. For example, if a bean definition is set to autowire by name, and it contains a master property (that is, it has a setMaster(..) method), Spring looks for a bean definition named `master`, and uses it to set the property.
byType	Allows a property to be autowired if exactly one bean of the property type exists in the container. If more than one exists, a fatal exception is thrown, which indicates that you may not use byType autowiring for that bean. If there are no matching beans, nothing happens; the property is not set.
constructor	Analogous to byType, but applies to constructor arguments. If there is not exactly one bean of the constructor argument type in the container, a fatal error is r

 1 package com.fuwh.test;
 2 
 3 public class People {
 4 
 5     private int id;
 6     private String name;
 7     private int age;
 8     
 9     private Dog dog;
10     
11     public Dog getDog() {
12         return dog;
13     }
14 
15     public void setDog(Dog dog) {
16         this.dog = dog;
17     }
18 
19     public int getId() {
20         return id;
21     }
22 
23     public void setId(int id) {
24         this.id = id;
25     }
26 
27     public String getName() {
28         return name;
29     }
30 
31     public void setName(String name) {
32         this.name = name;
33     }
34 
35     public int getAge() {
36         return age;
37     }
38 
39     public void setAge(int age) {
40         this.age = age;
41     }
42 
43     @Override
44     public String toString() {
45         return "People [id=" + id + ", name=" + name + ", age=" + age + ", dog=" + dog + "]";
46     }
47     
48     
49 }

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xsi:schemaLocation="http://www.springframework.org/schema/beans
 5         http://www.springframework.org/schema/beans/spring-beans.xsd">
 6 
 7     <bean id="dog" class="com.fuwh.test.Dog">
 8         <property name="id" value="001"></property>
 9         <property name="name" value="heihu"></property>
10         <property name="age" value="5"></property>
11     </bean>   
12     
13     <!-- 也可以在beans中定义autowire="byName" 这时候就对所有bean有效-->
14     <bean id="people" class="com.fuwh.test.People"  autowire="byName">
15         <property name="id" value="1"></property>
16         <property name="name" value="lisi"></property>
17         <property name="age" value="27"></property>
18     </bean>
19 
20 </beans>

 1 package com.fuwh.test;
 2 
 3 
 4 import org.junit.Before;
 5 import org.springframework.context.ApplicationContext;
 6 import org.springframework.context.support.ClassPathXmlApplicationContext;
 7 
 8 public class Test {
 9 
10     private ApplicationContext ac;    
11 
12     @Before
13     public void setUp() throws Exception {
14         ac=new ClassPathXmlApplicationContext("beans.xml");
15     }
16 
17     @org.junit.Test
18     public void test() {
19         People people =(People)ac.getBean("people");
20         System.out.println(people);
21     }
22 }

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原文地址：https://www.cnblogs.com/zerotomax/p/5720601.html

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