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context:component-scan base-package

创建时间：2016-08-19 投稿人： 浏览次数：2349
Element : component-scan
Scans the classpath for annotated components that will be auto-registered as Spring beans. By 
 default, the Spring-provided @Component, @Repository, @Service, and @Controller stereotypes will 
 be detected. Note: This tag implies the effects of the "annotation-config" tag, activating @Required, 
 @Autowired, @PostConstruct, @PreDestroy, @Resource, @PersistenceContext and @PersistenceUnit 
 annotations in the component classes, which is usually desired for autodetected components (without 
 external configuration). Turn off the "annotation-config" attribute to deactivate this default behavior, 
 for example in order to use custom BeanPostProcessor definitions for handling those annotations. 
 Note: You may use placeholders in package paths, but only resolved against system properties 
 (analogous to resource paths). A component scan results in new bean definition being registered; 
 Spring"s PropertyPlaceholderConfigurer will apply to those bean definitions just like to regular bean 
 definitions, but it won"t apply to the component scan settings themselves.

Content Model : (include-filter*, exclude-filter*)

上面文字，是人家官方解释。翻译如下：

扫描注释组件会自动注册为Spring bean的类路径。通过
 默认情况下，Spring提供@Component，@Repository，@Service和@Controller将定型
 被检测到。注意：这个标签意味着“注释的配置”标签的效果，激活@Required，
 @Autowired，@PostConstruct，@PreDestroy，@Resource，@PersistenceContext和@PersistenceUnit
 在组件类，这通常是所希望的用于自动检测部件注解（无
 外部配置）。关闭“注释的配置”属性停用​​此默认行为，
 例如，为了使用BeanPostProcessor的定义来处理这些注释。
 注意：您可以在包路径中使用的占位符，但只解决了对系统属性
 （类似于资源路径）。在新的bean定义组件扫描结果被注册;
 Spring的PropertyPlaceholderConfigurer将适用于那些bean定义，就像定期豆
 的定义，但它不适用于该组件扫描设置自己。

意思就是，这个，可以扫描controller ，也可以扫描，respository ,service等等 其他的，所有的注解。

但是，在配置扫描路径的时候需要注意，

@Controller,  只能  在 spring mvc-config.xml中，进行配置扫描。
其他的注解，包括，@Autowired , @Resource ,等等的注解，在 applicationContext.xml中，或者springmvc-config.xml中配置均可。

下面是我的web.xml配置。原文地址：http://blog.csdn.net/u012246342/article/details/52126286

<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>classpath:application*.xml</param-value>
	</context-param>
	<servlet>
		<servlet-name>springmvc</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>
				/WEB-INF/classes/springmvc-config.xml
			</param-value>
		</init-param>
		<load-on-startup>2</load-on-startup>
	</servlet>

springMVC的配置文件有这两个。

controller的 注解扫描，必须在springmvc-config.xml中进行配置，否则，虽然运行项目不报错，但是，请求的所有方法，均不会被扫描到。


其他的 注解扫描，可以在 这两个文件中任意进行配置，如果不进行配置，报错如下：


错误日志信息，本文最后。。


我的所有注解扫描配置，均写在 springmvc-config.xml 中。多个扫描路径，用 英文  ,  隔开。

最好写的详细一点，详细到具体的包，别配置全路径，全部扫描很慢的，影响效率

我的配置如下：

<context:component-scan base-package="com.wswhr.LoginServer.dao.*,com.wswhr.LoginServer.service.*,com.wswhr.LoginServer.springmvc.*" />


最后，没有配置 @Autowired 等等 其他配置，报错 日志如下。

严重: StandardWrapper.Throwable
org.springframework.beans.factory.BeanCreationException: Error creating bean with name "loginController": Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.wswhr.LoginServer.service.SystemUserService com.wswhr.LoginServer.springmvc.controller.LoginController.sysUserService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.wswhr.LoginServer.service.SystemUserService] 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)}
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:287)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
	at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:631)
	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:588)
	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:645)
	at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:508)
	at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:449)
	at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:133)
	at javax.servlet.GenericServlet.init(GenericServlet.java:212)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1213)
	at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1026)
	at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4451)
	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4768)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1061)
	at org.apache.catalina.core.StandardHost.start(StandardHost.java:822)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1061)
	at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
	at org.apache.catalina.core.StandardService.start(StandardService.java:525)
	at org.apache.catalina.core.StandardServer.start(StandardServer.java:759)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.wswhr.LoginServer.service.SystemUserService com.wswhr.LoginServer.springmvc.controller.LoginController.sysUserService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.wswhr.LoginServer.service.SystemUserService] 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)}
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:506)
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:284)
	... 34 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.wswhr.LoginServer.service.SystemUserService] 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)}
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:924)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:793)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:707)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:478)
	... 36 more

八月 19, 2016 4:43:10 下午 org.apache.catalina.core.StandardContext loadOnStartup
严重: Servlet /LoginSystem threw load() exception
org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.wswhr.LoginServer.service.SystemUserService] 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)}
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:924)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:793)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:707)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:478)
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:284)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
	at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:631)
	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:588)
	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:645)
	at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:508)
	at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:449)
	at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:133)
	at javax.servlet.GenericServlet.init(GenericServlet.java:212)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1213)
	at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1026)
	at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4451)
	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4768)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1061)
	at org.apache.catalina.core.StandardHost.start(StandardHost.java:822)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1061)
	at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
	at org.apache.catalina.core.StandardService.start(StandardService.java:525)
	at org.apache.catalina.core.StandardServer.start(StandardServer.java:759)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)


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