spring mvc中的注解说明

注解扫描

context:component-scan 包扫描

  <context:component-scan base-package="org.bdp">   
         <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>   
    </context:component-scan>  

该方式下的，不仅会扫描controoler层，同时会扫描@service和@repository的bean，此时会出现一些问题 这个尤其在springmvc+spring+hibernate等集成时最容易出问题的地，最典型的错误就是：

为了避免该情况的发生，可以添加use-default-filters="false"

即：

<context:component-scan base-package="org.bdp" use-default-filters="false">   
             <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>   
        </context:component-scan>

原因解析：

查看源码

protected void registerDefaultFilters() {
this.includeFilters.add(new AnnotationTypeFilter(Component.class));
ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();

try {
    this.includeFilters.add(new AnnotationTypeFilter(ClassUtils.forName("javax.annotation.ManagedBean", cl), false));
    this.logger.debug("JSR-250 'javax.annotation.ManagedBean' found and supported for component scanning");
} catch (ClassNotFoundException var4) {
    ;
}

try {
    this.includeFilters.add(new AnnotationTypeFilter(ClassUtils.forName("javax.inject.Named", cl), false));
    this.logger.debug("JSR-330 'javax.inject.Named' annotation found and supported for component scanning");
} catch (ClassNotFoundException var3) {
    ;
}}

可以知道，在扫描的时候会默认去扫描component Named。ManagedBean等的注解

@service等注解

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Service {
    String value() default "";
}

可以清楚的观察到@service注都是@component

原因找到以后：解决办法就是关闭使用默认的过滤器