Spring框架入门之基于Java注解配置bean

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