Spring--IOC容器——對象依賴關(guān)系（注解）

注解方式可以簡化spring的IOC容器的配置!

使用注解步驟：

  • 1）先引入context名稱空間
    xmlns:context="http://www.springframework.org/schema/context"
  • 2）開啟注解掃描
    <context:component-scan base-package="cn.itcast.e_anno2"></context:component-scan>
  • 3）使用注解
    通過注解的方式，把對象加入ioc容器。
    創(chuàng)建對象以及處理對象依賴關(guān)系，相關(guān)的注解：
    @Component指定把一個(gè)對象加入IOC容器
    @Repository作用同@Component； 在持久層使用
    @Service 作用同@Component； 在業(yè)務(wù)邏輯層使用
    @Controller作用同@Component； 在控制層使用
    @Resource屬性注入

總結(jié)：
1） 使用注解，可以簡化配置，且可以把對象加入IOC容器,及處理依賴關(guān)系(DI)
2） 注解可以和XML配置一起使用。

方法一

注解：

<?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"
       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 " >

<!--開啟注解掃描-->
    <context:component-scan base-package="com.huan"></context:component-scan>

</beans>

UserDao.java

package com.huan.BeanTest;

import org.springframework.stereotype.Component;

/**
 * Created by 馬歡歡 on 2017/6/24.
 */
@Component("userDao") //相當(dāng)于 bean.xml[<bean id =userDao class="com.huan.BeanTest.UserDao">]
public class UserDao {
    public void save(){
        System.out.println("db:操作數(shù)據(jù)庫");
    }
}

UserService.java

package com.huan.BeanTest;

import org.springframework.stereotype.Component;

import javax.annotation.Resource;

/**
 * Created by 馬歡歡 on 2017/6/24.
 */
@Component("userService")//userService對象，注入到ioc容器
public class UserService {
    //從IOC容器中找到userDao對象，注入到當(dāng)前字段
    /**
     * <bean id =userDao class="com.huan.BeanTest.UserDao">
     *  <property name = "userDao" ref ="userDao" ></property> 相當(dāng)于 @Resource(name = "userDao")
     *
     *  </bean>
     */
    @Resource(name = "userDao")
    private UserDao userDao;
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
    public void save(){
        userDao.save();
    }
}

UserAction.java

package com.huan.BeanTest;

import org.springframework.stereotype.Component;


import javax.annotation.Resource;

/**
 * Created by 馬歡歡 on 2017/6/24.
 */
@Component("userAction")
public class UserAction {
    @Resource(name = "userService")
    private UserService userService;
    public void execute(){
        userService.save();
    }
}

創(chuàng)建user對象

 @Test
    public void test2(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("Spring/applicationContext.xml");
        UserAction userAction = (UserAction) applicationContext.getBean("userAction");
        userAction.execute();
方法二

注解：

<?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"
       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 " >

<!--開啟注解掃描-->
    <context:component-scan base-package="com.huan"></context:component-scan>

</beans>

UserDao.java

package com.huan.BeanTest;

import org.springframework.stereotype.Component;

/**
 * Created by 馬歡歡 on 2017/6/24.
 */
@Component
public class UserDao {
    public void save(){
        System.out.println("db:操作數(shù)據(jù)庫zui");
    }
}

UserService.java


package com.huan.BeanTest;

import org.springframework.stereotype.Component;

import javax.annotation.Resource;

/**
 * Created by 馬歡歡 on 2017/6/24.
 */
@Component
public class UserService {
    
    @Resource//根據(jù)類型查找·[在容器中，該類型只有一個(gè)變量]
    private UserDao userDao;
    public void save(){
        userDao.save();
    }
}

UserAction.java

package com.huan.BeanTest;

import org.springframework.stereotype.Component;


import javax.annotation.Resource;

/**
 * Created by 馬歡歡 on 2017/6/24.
 */
@Component
public class UserAction {
    @Resource
    private UserService userService;
    public void execute(){
        userService.save();
    }
}

創(chuàng)建user對象

 @Test
    public void test2(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("Spring/applicationContext.xml");
        UserAction userAction = (UserAction) applicationContext.getBean("userAction");
        userAction.execute();
方法三

注解：

<?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"
       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 " >

<!--開啟注解掃描-->
    <context:component-scan base-package="com.huan"></context:component-scan>

</beans>

UserDao.java

package com.huan.BeanTest;

import org.springframework.stereotype.Repository;

/**
 * Created by 馬歡歡 on 2017/6/24.
 */
@Repository
public class UserDao {
    public void save(){
        System.out.println("db:操作數(shù)據(jù)庫zui");
    }
}

UserService.java


package com.huan.BeanTest;

import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

/**
 * Created by 馬歡歡 on 2017/6/24.
 */
@Service
public class UserService {

    @Resource
    private UserDao userDa;
    public void save(){
        userDa.save();
    }
}

UserAction.java

package com.huan.BeanTest;

import org.springframework.stereotype.Controller;

import javax.annotation.Resource;

/**
 * Created by 馬歡歡 on 2017/6/24.
 */
@Controller
public class UserAction {
    @Resource
    private UserService userService;
    public void execute(){
        userService.save();
    }
}

創(chuàng)建user對象

 @Test
    public void test2(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("Spring/applicationContext.xml");
        UserAction userAction = (UserAction) applicationContext.getBean("userAction");
        userAction.execute();
image.png

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