[Java知识库]@AutoWired和@Resource的区别

@AutoWired

spring的注解，默认通过类型注入，如果存在多个实例符合要求，则根据名称注入

@Resource

java自带的注解，默认通过名称注入，如过名称不存在，则根据类型进行注入

如果一个接口有多个实现类，通过这两个注解注入的时候

使用@Resource时报这样的错误

Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'com.example.demo.service.TestService' available: expected single matching bean but found 2: testServiceImpl1,testServiceImpl2
	at org.springframework.beans.factory.config.DependencyDescriptor.resolveNotUnique(DependencyDescriptor.java:220) ~[spring-beans-5.3.10.jar:5.3.10]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1358) ~[spring-beans-5.3.10.jar:5.3.10]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1300) ~[spring-beans-5.3.10.jar:5.3.10]
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:521) ~[spring-context-5.3.10.jar:5.3.10]
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:497) ~[spring-context-5.3.10.jar:5.3.10]
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:650) ~[spring-context-5.3.10.jar:5.3.10]
	at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:228) ~[spring-beans-5.3.10.jar:5.3.10]
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119) ~[spring-beans-5.3.10.jar:5.3.10]
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:318) ~[spring-context-5.3.10.jar:5.3.10]

使用@AutoWired时报这样的错误

Field testService in com.example.demo.DemoApplication required a single bean, but 2 were found:
	- testServiceImpl1: defined in file [D:\idea\work\demo\target\classes\com\example\demo\service\impl\TestServiceImpl1.class]
	- testServiceImpl2: defined in file [D:\idea\work\demo\target\classes\com\example\demo\service\impl\TestServiceImpl2.class]

则可以这样解决

1.在@AutoWired或者@Resource时，同时使用@Qualifier("testServiceImpl1")?来指定要使用的实现类

    @Autowired
	@Qualifier("testServiceImpl1")
	private TestService testService;

	@Resource
	@Qualifier("testServiceImpl1")
	private TestService testService1;

2.在实现类上方加@Primary，代表优先使用实现类

?这两种情况都可以解决上面的报错问题，如果两者同时使用，会优先取@Qualifier得结果

?