Spring框架入门之基于Java注解配置bean
一、Spring bean配置常用的注解
常用的有四个注解
- Controller: 用于控制器的注解
- Service : 用于service的注解
- Component： 用于基本组件的注解
- Repository：用于Dao层的注解
- 其实，对于spring来说，它根本无法识别controller，service等，它只知道只要你加了以上四个注解，它就帮你创建bean
- 简单来说，就是如果你在控制器上使用Component注解，或者使用Repository注解也是可以的，四种注解可以混用
- 但是，我们一般都按照上方所示的规则来使用注解，这样代码才有可读性
二、使用注解
要说的都在代码注释中，直接上代码：
包结构如下：
配置文件如下：beans-annotation.xml
<?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-4.1.xsd"> <!--
指定SpringIOC容器扫描的包
可以使用resource-pattern指定扫描的资源
-->
<!--
<context:component-scan base-package="me.spring.beans.annotation" resource-pattern="repository/*.class"></context:component-scan>
-->
<!--
<context:component-scan
base-package="me.spring.beans.annotation"
resource-pattern="repository/*.class"
use-default-filters="false">
-->
<!-- context:exclude-filter子节点指定要排除的组件
<context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
-->
<!-- include-filter指定包含直接点的组件，需要use-default-filters配合使用
<context:include-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
-->
<!--
<context:exclude-filter type="assignable" expression="org.springframework.stereotype.Repository"/>
<context:include-filter type="assignable" expression="org.springframework.stereotype.Repository"/>
-->
<!--
</context:component-scan>
-->
<context:component-scan base-package="me.spring.beans.annotation"></context:component-scan>
</beans>
me.spring.beans.annotation包下的类
package me.spring.beans.annotation; import org.springframework.stereotype.Component; @Component
public class TestObject { }
package me.spring.beans.generic.di; import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main { public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-generic-di.xml");
UserService userService = (UserService) ctx.getBean("userService");
userService.add();
}
}
me.spring.beans.annotation.controller包下的类：
package me.spring.beans.annotation.controller; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller; import me.spring.beans.annotation.service.UserService; /**
* 模拟表现层
* @author Administrator
*
*/
@Controller
public class UserController { @Autowired
private UserService userService;
public void execute() {
System.out.println("UserController's execute method");
userService.add();
}
}
me.spring.beans.repository包下的类
package me.spring.beans.annotation.repository; import org.springframework.stereotype.Repository; @Repository
public class UserJdbcRepository implements UserRepository { @Override
public void save() { System.out.println("UserJdbcRepository's save");
} } package me.spring.beans.annotation.repository; public interface UserRepository { public void save();
} package me.spring.beans.annotation.repository; import org.springframework.stereotype.Repository; /**
* 模拟持久化层
* @author Administrator
*
*/
@Repository
public class UserRepositoryImpl implements UserRepository{ @Override
public void save() { System.out.println("UserRepository's save method");
} }
me.spring.beans.service包下的类
package me.spring.beans.annotation.service; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service; import me.spring.beans.annotation.repository.UserRepository; /**
* 模拟业务层
* @author Administrator
*
*/
@Service
public class UserService { @Autowired
@Qualifier("userJdbcRepository")
private UserRepository userRepository;
public void add() {
System.out.println("UserService's add method");
userRepository.save();
}
}
参考：http://blog.csdn.net/u010837612/article/details/45577817