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[Java教程]为什么applicationContext.xml和spring


在刚学习SpringMVC框架整合时,你也许会产生疑问为什么Spring.

<context:component-scan base-package="myproject"> 和<context:component-scan base-package="myproject.controller" />

在这里有一个比较有意思的问题,初学者也会产生困惑,那么他究竟有何不同?我思考和查询很久,话不多说,也实践做起:

(1)只在applicationContext.

<context:component-scan base-package="myproject">

启动不报错,,但@Controller失效

 

(2)只在spring-servlet. Error creating bean with name 'org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping#0' defined in ServletContext resource [/WEB-INF/spring-mvc-......
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'commonController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private eis.service.ICollegeServer eis.controller.CommonController.collService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [eis.service.ICollegeServer] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
 

(3)在applicationContext.

不报错,请求正常,

总结:由此可以分析<context:component-scan base-package="myproject">主要过滤@Controller,同时还查资料了解<context:component-scan base-package="myproject.controller" /> 配置项不但启用了对类包进行扫描以实施注释驱动 Bean 定义的功能,同时还启用了注释驱动自动注入的功能。