spring学习(五)—通过注解方式创建对象和注入属性

最新推荐文章于 2025-05-25 18:51:26 发布

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本文介绍了Spring框架中使用注解进行配置的方法，包括通过注解创建对象、注入属性等核心概念，并提供了具体的代码示例。

内容来自传智博客学习视频

1.使用注解方式时需要的配置文件

<?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"> 
    <!-- 开启注解扫描 
         到包里面扫描类，方法，属性上的注解
    -->
    <context:component-scan base-package="anno"></context:component-scan>

</beans>

2.通过注解创建对象

package anno;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestAnno {

    @Test
    public void testUser(){
        ApplicationContext context = new ClassPathXmlApplicationContext("bean2.xml");
        User user = (User) context.getBean("user");
        user.add();
    }

}

package anno;

import org.springframework.stereotype.Component;

@Component(value="user")
public class User {

    public void add() {
        System.out.println("add...........");
    }

}

3.通过注解注入属性
通过两种方式注入属性

自动注入：@Autowired
指定注入：@Resource

package anno;

import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service("userService")
public class UserService {

       //1.通过注解方式完成属性注入：自动注解，根据类名来注入对象
       // @Autowired 
       // private UserDao userDao;

    //2.需指定注入的是哪个对象
    @Resource(name="userDao")
    private UserDao userDao;

    public void add(){
        System.out.println("add service........");
        userDao.add();
    }

}

package anno;

import org.springframework.stereotype.Component;

@Component("userDao")
public class UserDao {

    public void add() {
        System.out.println("add dao........");
    }

}

package anno;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestAnno {

    @Test
    public void testUser(){
        ApplicationContext context = new ClassPathXmlApplicationContext("bean2.xml");   
        UserService userService = (UserService) context.getBean("userService");
        userService.add();
    }

}