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  • Spring学习--通过注解配置 Bean (二)

    在 classpath 中扫描组件：

    当在组件类上使用了特定的注解之后 , 还需要在 Spring 的配置文件中声明 <context:component-scan>：

    • base-package 属性指定一个需要扫描的基类包 , Spring 容器将会扫描这个基类包里及其子包中的所有类。
    • 当需要扫描多个包时 , 可以使用逗号分隔。
    • 如果仅希望扫描特定的类而非基包下的所有类 , 可以使用 resource-pattern 属性过滤特定的类。
    • <context:include-filter> 子节点表示要包含的目标类。
    • <context:exclude-filter> 子节点表示要排除在外的目标类。
    • <context:component-scan> 下可以拥有若干个 <context:include-filter> 和 <context:exclude-filter> 子节点。

    <context:include-filter> 和 <context:exclude-filter> 子节点支持多种类型的过滤表达式：

    类别

    示例

    说明

    annotation

    com.xxx.XxxAnnotation

    所有标注 XxxAnnotation 的类。该类型采用目标类是否标注某个注解进行过滤

    assinable

    com.xxx.XxxService

    所有继承或扩展 XxxService 的类。该类型采用目标类是否继承或扩展某个特定类进行过滤

    aspectj

    com.xxx..*Service+

    所有类名以 Service 结束的类及继承或者扩展他们的类。该类型采用 AspectJ 表达式进行过滤

    regex

    com.xxx.anno..*

    所有 com.xxx.anno 包下的类。该类型采用正则表达式根据类的类名进行过滤

    custom

    com.xxx.XxxTypeFilter

    采用 XxxTypeFilter 通过代码的方式定义过滤规则。该类必须实现 org.springframework.core.type.TypeFilter 接口

    resource-pattern 属性过滤：

     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        xmlns:context="http://www.springframework.org/schema/context"
 5        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 6        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
 7 
 8     <!-- 指定 Spring IOC 容器扫描的包-->
 9     <!--
10         resource-pattern="repository/*.class"
11         只扫描repository下的所有类
12     -->
13     <context:component-scan base-package="com.itdjx.spring.annotation" resource-pattern="repository/*.class">
14 
15     </context:component-scan>
16 
17 </beans>
     1 package com.itdjx.spring.annotation;
 2 
 3 import com.itdjx.spring.annotation.controller.UserController;
 4 import com.itdjx.spring.annotation.repository.UserRepository;
 5 import com.itdjx.spring.annotation.service.UserService;
 6 import org.springframework.context.ApplicationContext;
 7 import org.springframework.context.support.ClassPathXmlApplicationContext;
 8 
 9 /**
10  * @author Wáng Chéng Dá
11  * @create 2017-03-03 9:34
12  */
13 public class Main {
14 
15     public static void main(String[] args) {
16         ApplicationContext cxt = new ClassPathXmlApplicationContext("beans-annotation.xml");
17         TestObject testObject = (TestObject) cxt.getBean("testObject");
18         System.out.println(testObject);
19 
20         UserController userController = (UserController) cxt.getBean("userController");
21         System.out.println(userController);
22 
23         UserService userService = (UserService) cxt.getBean("userService");
24         System.out.println(userService);
25 
26         UserRepository userRepository = (UserRepository) cxt.getBean("userRepository");
27         System.out.println(userRepository);
28 
29     }
30 }

    控制台输出：

    Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'testObject' available
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:687)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1207)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:284)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1081)
    at com.itdjx.spring.annotation.Main.main(Main.java:17)

    原因：配置文件中添加 resource-pattern="repository/*.class" 属性 , IOC 容器只扫描 repository 包下的类 , IOC 容器中只有 id 为 userRepository 的 bean 节点。

     1 package com.itdjx.spring.annotation;
 2 
 3 import com.itdjx.spring.annotation.controller.UserController;
 4 import com.itdjx.spring.annotation.repository.UserRepository;
 5 import com.itdjx.spring.annotation.service.UserService;
 6 import org.springframework.context.ApplicationContext;
 7 import org.springframework.context.support.ClassPathXmlApplicationContext;
 8 
 9 /**
10  * @author Wáng Chéng Dá
11  * @create 2017-03-03 9:34
12  */
13 public class Main {
14 
15     public static void main(String[] args) {
16         ApplicationContext cxt = new ClassPathXmlApplicationContext("beans-annotation.xml");
17   
18         UserRepository userRepository = (UserRepository) cxt.getBean("userRepository");
19         System.out.println(userRepository);
20 
21     }
22 }

     控制台输出：

    com.itdjx.spring.annotation.repository.UserRepositoryImpl@1e153c5

    <context:execlude-filter> 子节点：

    • annotation 属性：
     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        xmlns:context="http://www.springframework.org/schema/context"
 5        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 6        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
 7 
 8     <!-- 指定 Spring IOC 容器扫描的包 -->
 9     <context:component-scan base-package="com.itdjx.spring.annotation">
10         <!-- 排除包含(不包含) org.springframework.stereotype.Repository 的组件 -->
11        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
12     </context:component-scan>
13 
14 </beans>
     1 package com.itdjx.spring.annotation;
 2 
 3 import com.itdjx.spring.annotation.controller.UserController;
 4 import com.itdjx.spring.annotation.repository.UserRepository;
 5 import com.itdjx.spring.annotation.service.UserService;
 6 import org.springframework.context.ApplicationContext;
 7 import org.springframework.context.support.ClassPathXmlApplicationContext;
 8 
 9 /**
10  * @author Wáng Chéng Dá
11  * @create 2017-03-03 9:34
12  */
13 public class Main {
14 
15     public static void main(String[] args) {
16         ApplicationContext cxt = new ClassPathXmlApplicationContext("beans-annotation.xml");
17         TestObject testObject = (TestObject) cxt.getBean("testObject");
18         System.out.println(testObject);
19 
20         UserController userController = (UserController) cxt.getBean("userController");
21         System.out.println(userController);
22 
23         UserService userService = (UserService) cxt.getBean("userService");
24         System.out.println(userService);
25 
26         UserRepository userRepository = (UserRepository) cxt.getBean("userRepository");
27         System.out.println(userRepository);
28 
29     }
30 }

    控制台输出：

    Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'userRepository' available
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:687)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1207)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:284)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1081)
    at com.itdjx.spring.annotation.Main.main(Main.java:26)
    com.itdjx.spring.annotation.TestObject@13f29ff
    com.itdjx.spring.annotation.controller.UserController@1e8c3cb
    com.itdjx.spring.annotation.service.UserService@3f38c4

    原因：IOC 容器中不包含 org.springframework.stereotype.Repository 的组件 , 也就是 IOC 容器中没有 id 为 userRepository 的 bean 节点。

    • assignable 属性：
     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        xmlns:context="http://www.springframework.org/schema/context"
 5        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 6        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
 7 
 8     <!-- 指定 Spring IOC 容器扫描的包 -->
 9     <context:component-scan base-package="com.itdjx.spring.annotation">
10         <!-- 排除(不包含) com.itdjx.spring.annotation.repository.UserRepository 以及他的实现类 -->
11        <context:exclude-filter type="assignable" expression="com.itdjx.spring.annotation.repository.UserRepository"/>
12     </context:component-scan>
13 
14 </beans>

    控制台输出：

    com.itdjx.spring.annotation.TestObject@422e18
    com.itdjx.spring.annotation.controller.UserController@17159c0
    com.itdjx.spring.annotation.service.UserService@27ba32
    Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'userRepository' available
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:687)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1207)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:284)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1081)
    at com.itdjx.spring.annotation.Main.main(Main.java:26)

    原因：IOC 容器中没有 id 为 userRepository 的 bean 节点。

    <context:include-filter> 子节点：

    • annotation 属性：
     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        xmlns:context="http://www.springframework.org/schema/context"
 5        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 6        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
 7 
 8     <!-- 指定 Spring IOC 容器扫描的包 -->
 9     <context:component-scan base-package="com.itdjx.spring.annotation">
10         <!-- 包含 org.springframework.stereotype.Repository 的组件 -->
11        <context:include-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
12     </context:component-scan>
13 
14 </beans>

    控制台输出：

    com.itdjx.spring.annotation.TestObject@27ba32
    com.itdjx.spring.annotation.controller.UserController@f82753
    com.itdjx.spring.annotation.service.UserService@10fe47a
    com.itdjx.spring.annotation.repository.UserRepositoryImpl@2b0582

    <context:include-filter> 子节点没有生效：该子节点需要和 use-default-filters 属性配合使用。

     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        xmlns:context="http://www.springframework.org/schema/context"
 5        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 6        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
 7 
 8     <!-- 指定 Spring IOC 容器扫描的包 -->
 9     <context:component-scan base-package="com.itdjx.spring.annotation" use-default-filters="false">
10         <!-- 包含 org.springframework.stereotype.Repository 的组件 -->
11        <context:include-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
12     </context:component-scan>
13 
14 </beans>

    控制台输出：

    Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'testObject' available
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:687)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1207)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:284)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1081)
    at com.itdjx.spring.annotation.Main.main(Main.java:17)

    原因：IOC 容器中只存在 id 为 userRepository 的 bean 节点 。

     1 package com.itdjx.spring.annotation;
 2 
 3 import com.itdjx.spring.annotation.controller.UserController;
 4 import com.itdjx.spring.annotation.repository.UserRepository;
 5 import com.itdjx.spring.annotation.service.UserService;
 6 import org.springframework.context.ApplicationContext;
 7 import org.springframework.context.support.ClassPathXmlApplicationContext;
 8 
 9 /**
10  * @author Wáng Chéng Dá
11  * @create 2017-03-03 9:34
12  */
13 public class Main {
14 
15     public static void main(String[] args) {
16         ApplicationContext cxt = new ClassPathXmlApplicationContext("beans-annotation.xml");
17 
18         UserRepository userRepository = (UserRepository) cxt.getBean("userRepository");
19         System.out.println(userRepository);
20 
21     }
22 }

    控制台输出：

    com.itdjx.spring.annotation.repository.UserRepositoryImpl@1406a1
    • assignable 属性：
     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        xmlns:context="http://www.springframework.org/schema/context"
 5        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 6        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
 7 
 8     <!-- 指定 Spring IOC 容器扫描的包 -->
 9     <context:component-scan base-package="com.itdjx.spring.annotation" use-default-filters="false">
10         <!-- 包含 com.itdjx.spring.annotation.repository.UserRepository 以及他的实现类 -->
11        <context:include-filter type="assignable" expression="com.itdjx.spring.annotation.repository.UserRepository"/>
12     </context:component-scan>
13 
14 </beans>

    控制台输出：

    com.itdjx.spring.annotation.repository.UserRepositoryImpl@af004b
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  • 原文地址：https://www.cnblogs.com/chinda/p/6495776.html
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