spring 注解注入属性

一、步骤

创建一个service类，创建dao类 ，在service得到dao对象

• 注入属性有第一个注解@Autowired
  （1）创建dao和service对象
  （2）在service类里定义dao类型属性
  （3）自动注入值：@Autowired注解
• 注入属性第二个注解@Resourc(name="注解创建对象的value")

二、代码

UserService.java

import javax.annotation.Resource;

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

import work.zhangdoudou.dao.UserDao;

@Service(value="userservice")
public class UserService {
    //得到dao的对象
    //1定义到类型属性
    //在到属性上使用注解完成
    //@Autowired
    @Resource(name="userdao")
    private UserDao userDao;
    //使用注解方式时不需要set方法
    
    public void service(){
        System.out.println("service----------");
        userDao.dao();  
    }
}

UserDao.java

package work.zhangdoudou.dao;

import org.springframework.stereotype.Component;

@Component(value="userdao")
public class UserDao {
    public void dao(){
        System.out.println("dao--------");
    }
}

配置文件applicationContext.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-4.0.xsd">
        
    <!-- 配置开启注解的扫描 -->
    <!-- 扫描所有包 -->
    <context:component-scan base-package="work.zhangdoudou"></context:component-scan>
    
    <!-- 扫描属性上面的注解 -->  
    <!-- <context:annotation-config ></context:annotation-config> -->
</beans>

测试类Testservice.java

package work.zhangdoudou.test;

import static org.junit.Assert.*;

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

import work.zhangdoudou.anno.User;
import work.zhangdoudou.service.UserService;

public class Testservice {

    @Test
    public void test() {
        ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");
        UserService userService=(UserService)context.getBean("userservice");
        userService.service();
    }

}

三、运行结果

image.png