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：
<?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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- 指定 Spring IOC 容器扫描的包-->
<!--
resource-pattern="repository/*.class"
只扫描repository下的所有类
-->
<context:component-scan base-package="com.itdjx.spring.annotation" resource-pattern="repository/*.class"> </context:component-scan> </beans>
package com.itdjx.spring.annotation; import com.itdjx.spring.annotation.controller.UserController;
import com.itdjx.spring.annotation.repository.UserRepository;
import com.itdjx.spring.annotation.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; /**
* @author Wáng Chéng Dá
* @create 2017-03-03 9:34
*/
public class Main { public static void main(String[] args) {
ApplicationContext cxt = new ClassPathXmlApplicationContext("beans-annotation.xml");
TestObject testObject = (TestObject) cxt.getBean("testObject");
System.out.println(testObject); UserController userController = (UserController) cxt.getBean("userController");
System.out.println(userController); UserService userService = (UserService) cxt.getBean("userService");
System.out.println(userService); UserRepository userRepository = (UserRepository) cxt.getBean("userRepository");
System.out.println(userRepository); }
}
控制台输出：
Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'testObject' available |
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。
package com.itdjx.spring.annotation; import com.itdjx.spring.annotation.controller.UserController;
import com.itdjx.spring.annotation.repository.UserRepository;
import com.itdjx.spring.annotation.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; /**
* @author Wáng Chéng Dá
* @create 2017-03-03 9:34
*/
public class Main { public static void main(String[] args) {
ApplicationContext cxt = new ClassPathXmlApplicationContext("beans-annotation.xml"); UserRepository userRepository = (UserRepository) cxt.getBean("userRepository");
System.out.println(userRepository); }
}
控制台输出：
| com.itdjx.spring.annotation.repository.UserRepositoryImpl@1e153c5 |
<context:execlude-filter> 子节点：
- annotation 属性：
<?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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- 指定 Spring IOC 容器扫描的包 -->
<context:component-scan base-package="com.itdjx.spring.annotation">
<!-- 排除包含(不包含) org.springframework.stereotype.Repository 的组件 -->
<context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
</context:component-scan> </beans>
package com.itdjx.spring.annotation; import com.itdjx.spring.annotation.controller.UserController;
import com.itdjx.spring.annotation.repository.UserRepository;
import com.itdjx.spring.annotation.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; /**
* @author Wáng Chéng Dá
* @create 2017-03-03 9:34
*/
public class Main { public static void main(String[] args) {
ApplicationContext cxt = new ClassPathXmlApplicationContext("beans-annotation.xml");
TestObject testObject = (TestObject) cxt.getBean("testObject");
System.out.println(testObject); UserController userController = (UserController) cxt.getBean("userController");
System.out.println(userController); UserService userService = (UserService) cxt.getBean("userService");
System.out.println(userService); UserRepository userRepository = (UserRepository) cxt.getBean("userRepository");
System.out.println(userRepository); }
}
控制台输出：
Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'userRepository' available |
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：
<?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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- 指定 Spring IOC 容器扫描的包 -->
<context:component-scan base-package="com.itdjx.spring.annotation">
<!-- 排除(不包含) com.itdjx.spring.annotation.repository.UserRepository 以及他的实现类 -->
<context:exclude-filter type="assignable" expression="com.itdjx.spring.annotation.repository.UserRepository"/>
</context:component-scan> </beans>
控制台输出：
com.itdjx.spring.annotation.TestObject@422e18 |
原因：IOC 容器中没有 id 为 userRepository 的 bean 节点。
<context:include-filter> 子节点：
- annotation 属性：
<?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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- 指定 Spring IOC 容器扫描的包 -->
<context:component-scan base-package="com.itdjx.spring.annotation">
<!-- 包含 org.springframework.stereotype.Repository 的组件 -->
<context:include-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
</context:component-scan> </beans>
控制台输出：
com.itdjx.spring.annotation.TestObject@27ba32 |
<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。
<?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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- 指定 Spring IOC 容器扫描的包 -->
<context:component-scan base-package="com.itdjx.spring.annotation" use-default-filters="false">
<!-- 包含 org.springframework.stereotype.Repository 的组件 -->
<context:include-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
</context:component-scan> </beans>
控制台输出：
Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'testObject' available |
原因：IOC 容器中只存在 id 为 userRepository 的 bean 节点 。
package com.itdjx.spring.annotation; import com.itdjx.spring.annotation.controller.UserController;
import com.itdjx.spring.annotation.repository.UserRepository;
import com.itdjx.spring.annotation.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; /**
* @author Wáng Chéng Dá
* @create 2017-03-03 9:34
*/
public class Main { public static void main(String[] args) {
ApplicationContext cxt = new ClassPathXmlApplicationContext("beans-annotation.xml"); UserRepository userRepository = (UserRepository) cxt.getBean("userRepository");
System.out.println(userRepository); }
}
控制台输出：
| com.itdjx.spring.annotation.repository.UserRepositoryImpl@1406a1 |
- assignable 属性：
<?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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- 指定 Spring IOC 容器扫描的包 -->
<context:component-scan base-package="com.itdjx.spring.annotation" use-default-filters="false">
<!-- 包含 com.itdjx.spring.annotation.repository.UserRepository 以及他的实现类 -->
<context:include-filter type="assignable" expression="com.itdjx.spring.annotation.repository.UserRepository"/>
</context:component-scan> </beans>
控制台输出：
| com.itdjx.spring.annotation.repository.UserRepositoryImpl@af004b |