apring中@Primary和@Qualifier注解的区别

关注

原创最新推荐文章于 2026-06-03 00:03:01 发布 7k 阅读 AI 写同款· GEO 优化 ›

矩阵束(Matrix Pencil)入门：从通信系统到控制理论，它为何是建模利器？本文深入探讨矩阵束(Matrix Pencil)在通信系统与控制理论中的关键作用，揭示其作为复杂系统建模利器的独特价值。从MIMO系统的多径干扰分析到电力系统稳定性判据，矩阵束通过`A-λB`方程求解提供精准建模方案，显著提升5G通信和工业控制等领域的性能表现。阅读详情

首先说明一下两个注解的作用

@Primary：在众多相同的bean中，优先选择用@Primary注解的bean（该注解加在各个bean上）

@Qualifier：在众多相同的bean中，@Qualifier指定需要注入的bean（该注解跟随在@Autowired后）

下面一个小例子：

1.ServiceTest接口

public interface ServiceTest {
	void doSomething();
}

2.两个实现类

@Service("service1")
public class Service1 implements ServiceTest{

	@Override
	public void doSomething() {
		System.out.println("this is service1");
	}
	
}

@Service("service2")
public class Service2 implements ServiceTest{

	@Override
	public void doSomething() {
		System.out.println("this is service2");
	}

}

3 测试一

@Autowired
private ServiceTest serviceTest;
	     
@RequestMapping("showServiceTest")
public void showServiceTest(HttpServletRequest request, HttpServletResponse response) {
    this.serviceTest.doSomething();
}

启动报错
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'analysisTest': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.grac.web.controller.analysis.ServiceTest com.grac.web.controller.analysis.AnalysisTest.serviceTest; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.grac.web.controller.analysis.ServiceTest] is defined: expected single matching bean but found 2: service1,service2

4 测试二

	@Autowired
	@Qualifier("service2")
	private ServiceTest serviceTest;
	     
    @RequestMapping("showServiceTest")
    public void showServiceTest(HttpServletRequest request, HttpServletResponse response) {
        this.serviceTest.doSomething();
    }

控制台输出

this is service2

5 测试三
在service1上加入@Primary注解

@Service("service1")
@Primary
public class Service1 implements ServiceTest{

	@Override
	public void doSomething() {
		System.out.println("this is service1");
	}
	
}

	@Autowired
	private ServiceTest serviceTest;
	     
    @RequestMapping("showServiceTest")
    public void showServiceTest(HttpServletRequest request, HttpServletResponse response) {
        this.serviceTest.doSomething();
    }

控制台输出