我正在学习Spring 3，我似乎没有掌握<context:annotation-config>和<context:component-scan>背后的功能。
从我读到的内容来看，它们似乎处理不同的注释(@Required， @Autowired等vs @Component， @Repository， @Service等)，但从我读到的内容来看，它们注册了相同的bean后处理器类。
更让我困惑的是，在<context:component-scan>上有一个annotation-config属性。
有人能解释一下这些标签吗?什么是相似的，什么是不同的，是一个被另一个取代，它们互相完善，我需要其中一个吗，还是两个?
当前回答
Spring允许您做两件事:
自动装配bean 自动发现bean
1. Autowiring Usually in applicationContext.xml you define beans and other beans are wired using constructor or setter methods. You can wire beans using XML or annotations. In case you use annotations, you need to activate annotations and you have to add <context:annotation-config /> in applicationContext.xml. This will simplify the structure of the tag from applicationContext.xml, because you will not have to manually wire beans (constructor or setter). You can use @Autowire annotation and the beans will be wired by type.
避免手动XML配置的一个步骤是
2. Autodiscovery Autodiscovery is simplifying the XML one step further, in the sense that you don't even need too add the <bean> tag in applicationContext.xml. You just mark the specific beans with one of the following annotation and Spring will automatically wire the marked beans and their dependencies into the Spring container. The annotations are as follow: @Controller, @Service, @Component, @Repository. By using <context:component-scan> and pointing the base package, Spring will auto-discover and wire the components into Spring container.
作为结论:
<context:annotation-config />被使用是为了能够使用 @ autowired注解 <context:component-scan />用于确定搜索 特定的bean和自动装配的尝试。
其他回答
<context:component-scan/>自定义标记除了主要负责扫描java包和从类路径注册bean定义外，还注册了与by所做的相同的bean定义集。
如果出于某种原因要避免这种默认bean定义的注册，方法是在component-scan中指定一个额外的“annotation-config”属性，如下所示:
<context:component-scan basePackages="" annotation-config="false"/>
参考: http://www.java-allandsundry.com/2012/12/contextcomponent-scan-contextannotation.html
我发现了一个很好的总结，说明哪些注释被哪些声明拾取。通过研究它，你会发现<context:component-scan/>识别了<context:annotation-config/>识别的注释的超集，即:
@组件，@服务，@存储库，@控制器，@端点 @Configuration， @Bean， @Lazy， @Scope， @Order， @Primary， @Profile， @DependsOn， @Import， @ImportResource
正如您所看到的，<context:component-scan/>逻辑上扩展了<context:annotation-config/>，具有CLASSPATH组件扫描和Java @Configuration特性。
<context:component-scan /> implicitly enables <context:annotation-config/>
try with <context:component-scan base-package="…" annotation-config="false"/>，在你的配置中@Service， @Repository， @Component工作正常，但是@Autowired，@Resource和@Inject不工作。
这意味着AutowiredAnnotationBeanPostProcessor将不会被启用，Spring容器将不会处理自动装配注释。
>激活bean中许多不同的注释，无论它们是用XML定义的还是通过组件扫描定义的。
>用于不使用XML定义bean
欲了解更多信息，请阅读:
3.9. 基于注释的容器配置 3.10. 类路径扫描和托管组件
Spring允许您做两件事:
自动装配bean 自动发现bean
1. Autowiring Usually in applicationContext.xml you define beans and other beans are wired using constructor or setter methods. You can wire beans using XML or annotations. In case you use annotations, you need to activate annotations and you have to add <context:annotation-config /> in applicationContext.xml. This will simplify the structure of the tag from applicationContext.xml, because you will not have to manually wire beans (constructor or setter). You can use @Autowire annotation and the beans will be wired by type.
避免手动XML配置的一个步骤是
2. Autodiscovery Autodiscovery is simplifying the XML one step further, in the sense that you don't even need too add the <bean> tag in applicationContext.xml. You just mark the specific beans with one of the following annotation and Spring will automatically wire the marked beans and their dependencies into the Spring container. The annotations are as follow: @Controller, @Service, @Component, @Repository. By using <context:component-scan> and pointing the base package, Spring will auto-discover and wire the components into Spring container.
作为结论:
<context:annotation-config />被使用是为了能够使用 @ autowired注解 <context:component-scan />用于确定搜索 特定的bean和自动装配的尝试。
