\@Autowired同名Bean问题修复

@Autowired同名Bean问题修复

新建一个SpringDemo项目，注意先修改好发行版，出错都是因为出场Setting没设置对，以及自动生成SpringBoot项目时，xml中指定了，要将其去掉或修改为8，不然import Maven又会使设置生效。

新建两个不同包下的同名类Test，类结构如图：

Application：

Real类：

这里不把@autowired写到Application中是因为写了也不会注入，SpringBoot会把Application的注入忽略，

所以把@Autowired写到了Real类中，new去使用它。

以上图结构run,返回以下结果，很容易看出是在Bean产生了冲突：

2023-09-21 17:42:01.596  INFO 28712 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication using Java 1.8.0_333 on DESKTOP-7TNR5U5 with PID 28712 (D:\IdeaProjects\demo\demo2\target\classes started by hspcadmin in D:\IdeaProjects\demo)
2023-09-21 17:42:01.601  INFO 28712 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to 1 default profile: "default"
2023-09-21 17:42:01.847  WARN 28712 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanDefinitionStoreException: Failed to parse configuration class [com.example.demo.DemoApplication]; nested exception is org.springframework.context.annotation.ConflictingBeanDefinitionException: Annotation-specified bean name 'test' for bean class [com.example.demo.test2.Test] conflicts with existing, non-compatible bean definition of same name and class [com.example.demo.test.Test]
2023-09-21 17:42:06.009 ERROR 28712 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanDefinitionStoreException: Failed to parse configuration class [com.example.demo.DemoApplication]; nested exception is org.springframework.context.annotation.ConflictingBeanDefinitionException: Annotation-specified bean name 'test' for bean class [com.example.demo.test2.Test] conflicts with existing, non-compatible bean definition of same name and class [com.example.demo.test.Test]
	at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:188) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:331) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:247) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:311) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:112) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:746) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:564) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147) ~[spring-boot-2.7.6.jar:2.7.6]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:731) [spring-boot-2.7.6.jar:2.7.6]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408) [spring-boot-2.7.6.jar:2.7.6]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:307) [spring-boot-2.7.6.jar:2.7.6]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1303) [spring-boot-2.7.6.jar:2.7.6]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1292) [spring-boot-2.7.6.jar:2.7.6]
	at com.example.demo.DemoApplication.main(DemoApplication.java:11) [classes/:na]
Caused by: org.springframework.context.annotation.ConflictingBeanDefinitionException: Annotation-specified bean name 'test' for bean class [com.example.demo.test2.Test] conflicts with existing, non-compatible bean definition of same name and class [com.example.demo.test.Test]
	at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.checkCandidate(ClassPathBeanDefinitionScanner.java:349) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.doScan(ClassPathBeanDefinitionScanner.java:287) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.annotation.ComponentScanAnnotationParser.parse(ComponentScanAnnotationParser.java:128) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:295) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:249) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:206) ~[spring-context-5.3.24.jar:5.3.24]
	at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:174) ~[spring-context-5.3.24.jar:5.3.24]
	... 13 common frames omitted

与目标 VM 断开连接, 地址为: ''127.0.0.1:56835'，传输: '套接字''

如何判断是@Autowired注入时冲突还是容器都放不进去？注释掉@Autowired，发现仍然报该错，说明Factory不允许创建同类名Bean不加以区分

现在创建一个子项目，作为demo的依赖模块的demo2，并将test2的类移动到demo2模块下，且添加两模块间的依赖关系，如下图：

不加执行结果：

2023-09-21 17:49:31.990  INFO 34544 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication using Java 1.8.0_333 on DESKTOP-7TNR5U5 with PID 34544 (D:\IdeaProjects\demo\demo2\target\classes started by hspcadmin in D:\IdeaProjects\demo)
2023-09-21 17:49:31.995  INFO 34544 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to 1 default profile: "default"
2023-09-21 17:49:32.652  INFO 34544 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-09-21 17:49:32.658  INFO 34544 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-09-21 17:49:32.658  INFO 34544 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.69]
2023-09-21 17:49:32.761  INFO 34544 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-09-21 17:49:32.761  INFO 34544 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 720 ms
2023-09-21 17:49:33.020  INFO 34544 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2023-09-21 17:49:33.027  INFO 34544 --- [           main] com.example.demo.DemoApplication         : Started DemoApplication in 1.401 seconds (JVM running for 2.902)

发现并没有报错！说明Factory的错没有报出，但不知道此时bean，添加打印BeanName

String[] beanDefinitionNames = ac.getBeanDefinitionNames();
        for (String beanDefinitionName : beanDefinitionNames) {
            System.out.println(beanDefinitionName);
        }

可以看到确实有一个test对象，但是不知道是test1的还是test2，换个方法ac.getBeanNamesForType(Test.class);注意Test导入的路径要不同

结果发现： test为applicaton本模块的Test类，而子模块没有注入加@Autowired调用一下看能否正常用，发现报了空指针，说明没注入进来，Factory中有，但是却没注入，很奇怪：

最后可以得出结论。

对于正常的同名Bean，会直接报错，但是如果存在依赖关系，那么可能会导致报错被吞，并且有时候可能会直接断开VM连接。

而如果已经出现了同名错误，但是没报出，@Autowired此时是失效的了，可以直接理解成多Component无法注入，虽然此时Factory中有对象，但是由于有错在先，仍不允许注入Bean

在出现同名Bean的情况下就不要考虑注入规则ByType/ByName了，因为有错在先，可以理解成Spring未考虑的问题。

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\@Autowired同名Bean问题修复

@Autowired同名Bean问题修复

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