Spring自动注入对象，通过Junit加载Spring容器测试自动注入。

1、创建接口对象CompactDisc

public interface CompactDisc {
    void play();
}

2、创建接口的实现类CDImpl

@Component注解告诉Spring容器创建这个Bean

@Component
public class CDImpl implements CompactDisc {
    @Override
    public void play() {
        System.out.println("接口的实现类");
    }
}

3、创建Spring配置信息
<?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"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       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
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">

    <!--开启组件扫描，spring容器扫描指定的包，然后自动创建对象-->
    <context:component-scan base-package="com.imooc.impl"/>
</beans>

4、创建测试类

//junit启动时加载Spring的配置，整合Spring-junit
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({"classpath:spring/spring-autowire.xml"})
public class BaseTest {

}

public class TestPlay extends BaseTest{
      //@Autowired注解将spring创建Bean注入到TestPlay这个对象中
      @Autowired
    private CDImpl cd;

    @Test
    public void test() {
        cd.play();
    }
}