Spring课程 Spring入门篇 4-2 Spring bean装配（下）之Autowired注解说明1

课程链接：

1　　　　解析

2　　　　代码演练

1　　　　解析

1.1　　@Required注解

该注解适用于bean属性的set方法

1.2　　@Autowired

作用：

是为了把依赖的对象，自动的注入到bean里

使用方式：

1　　@autowired required的默认值为false

2　　每个类中只有一个构造器被标记为required=true

3　　@autowired（required=false）：如果找不到实体类，不报错。

4　　可以添加到成员变量或者方法上边

2　　　　代码演练

2.1　　autowired作为成员变量注解

实体类：

package com.imooc.beanannotation.injection.service;

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

import com.imooc.beanannotation.injection.dao.InjectionDao;

@Service
public class InjectionServiceImpl implements InjectionService {

    @Autowired
    private InjectionDao injectionDao;

    @Override
    public void save(String sArgs) {
        injectionDao.save(sArgs);
        // TODO Auto-generated method stub
        System.out.println("开始保存！！！"+sArgs);
    }

}

dao类：

package com.imooc.beanannotation.injection.dao;

import org.springframework.stereotype.Repository;

@Repository
public class InjectionDaoImpl implements InjectionDao{

    @Override
    public void save(String args) {
        // TODO Auto-generated method stub
        System.out.println("保存======="+args);
    }

}

测试类：

package com.imooc.beanannotation.injection2;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.BlockJUnit4ClassRunner;

import com.imooc.beanannotation.injection.service.InjectionService;
import com.imooc.test.base.UnitTestBase;

@RunWith(BlockJUnit4ClassRunner.class)
public class TestInjectionService extends UnitTestBase{

    public TestInjectionService() {
        super("classpath*:spring-beanannotation-injection.xml");
        // TODO Auto-generated constructor stub
    }

    @Test
    public void testInjectionServiceConstruct(){
        try {
            InjectionService iService = super.getbean("injectionServiceImpl");
            iService.save("12346");
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

}

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.xsd">

<context:component-scan base-package="com.imooc.beanannotation"></context:component-scan>

</beans>

打印结果：

三月 10, 2019 11:16:29 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@52633079: startup date [Sun Mar 10 11:16:29 CST 2019]; root of context hierarchy
三月 10, 2019 11:16:29 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from URL [file:/F:/xiangmu3/Xin/FuQiang/Spring/ddwei-dao/target/classes/spring-beanannotation-injection.xml]
保存=======12346
三月 10, 2019 11:16:30 上午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@52633079: startup date [Sun Mar 10 11:16:29 CST 2019]; root of context hierarchy
开始保存！！！

2.2　　autowired作为set方法注解

实体类：

package com.imooc.beanannotation.injection.service;

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

import com.imooc.beanannotation.injection.dao.InjectionDao;

@Service
public class InjectionServiceImpl implements InjectionService {

    private InjectionDao injectionDao;

    @Autowired
    public void setInjectionDao(InjectionDao injectionDao) {
        this.injectionDao = injectionDao;
    }

    @Override
    public void save(String sArgs) {
        injectionDao.save(sArgs);
        // TODO Auto-generated method stub
        System.out.println("开始保存！！！"+sArgs);
    }

}

打印结果：

三月 10, 2019 11:21:25 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5abce07: startup date [Sun Mar 10 11:21:25 CST 2019]; root of context hierarchy
三月 10, 2019 11:21:25 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from URL [file:/F:/xiangmu3/Xin/FuQiang/Spring/ddwei-dao/target/classes/spring-beanannotation-injection.xml]
保存=======12346
开始保存！！！12346
三月 10, 2019 11:21:26 上午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@5abce07: startup date [Sun Mar 10 11:21:25 CST 2019]; root of context hierarchy

2.3　　autowired作为构造方法注解

实体类：

package com.imooc.beanannotation.injection.service;

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

import com.imooc.beanannotation.injection.dao.InjectionDao;

@Service
public class InjectionServiceImpl implements InjectionService {

    private InjectionDao injectionDao;

    public void setInjectionDao(InjectionDao injectionDao) {
        this.injectionDao = injectionDao;
    }

    @Autowired
    public InjectionServiceImpl(InjectionDao injectionDao) {
        super();
        this.injectionDao = injectionDao;
    }

    @Override
    public void save(String sArgs) {
        injectionDao.save(sArgs);
        // TODO Auto-generated method stub
        System.out.println("开始保存！！！"+sArgs);
    }

}

打印结果：

三月 10, 2019 11:24:33 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5abce07: startup date [Sun Mar 10 11:24:33 CST 2019]; root of context hierarchy
三月 10, 2019 11:24:34 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from URL [file:/F:/xiangmu3/Xin/FuQiang/Spring/ddwei-dao/target/classes/spring-beanannotation-injection.xml]
保存=======12346
三月 10, 2019 11:24:34 上午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@5abce07: startup date [Sun Mar 10 11:24:33 CST 2019]; root of context hierarchy
开始保存！！！