spring装配bean-自动化装配

深藏阁楼爱情的钟 2021-11-17 03:10 447阅读 0赞

**开启组件扫描**  
1 通过javabean的方式配置

package soundsysem
    import org.springframework.context.annotation.componentScan;
    import org.springframework.context.annotation.Configuration
    
    @Configuration
    @ComponentScan
    public class CDPlayerConfig{
    	
    }

备注:如果没有其他配置的话,spring将会扫描CDPlayerConfig所在的包,以及这个包下的子包.也可以通过参数来  
配置扫描包@ComponentScan(basePackages=“soundsystem”)可简写为@ComponentScan(“soundsystem”),多个用逗号隔开,@ComponentScan(basePackages=\{“soundsystem”,“video”\}).除了传表示包路径的字符串以外还可以传class,  
@ComponentScan(basePackages=\{CDPlayer.class,DVDPlayer.class\}),以防止代码重构,包路径改变

2 通过xml的方式配置

<?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.springframewotrk.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="soundsystem" />
    </beans>

测试

package soundsystem;
    import static org.junit.Assert.*
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.test.context.ContextConfiguration;
    import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
    
    @RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(classes=CDPlayerConfig.class)
    public class CDPlayerTest{
    	@Autowaired
    	private CompactDisc cd;
    	
    	@Test
    	public void cdSouldNotBeNull(){
    		assetNotNull(cd);
    	}
    	
    }

为扫描的bean命名

@Component("lonelyHeartsClub")
    public class SgtPeppers implements CompactDisc {
    
    }
    
    package soundsystem;
    import javax.inject.Named;
    @Named("lonelyHeartsClub")
    public class SgtPeppers implements CompactDisc{
    
    }

说明:@Component是spring的注解,@Named是Java依赖注入规范提供的注解.Spring支持将@Named注解作为@Component的替代方案.两者之间有一些细微的差别,但是在大多数场景中两者是可以相互替换的