《標記》-在自定義的Spring攔截器中通過request獲取到該請求對應於Controller中的目標method方法對象

爲什麼要讀取method方法對象？

當然拿到Method對象我們可以做很多事，例如權限認證的時候，判斷用戶是否有訪問該方法的權限。

spring-webmvc-3.1.0.RELEASE及以上版本

最終配置--------------------------------------------begin

<bean class="org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator" /> 

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"/>

<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"> 

<property name="interceptors">

<list>

<bean class="com.chenzhou.examples.erm.util.interceptor.LoginInterceptor"/>

</list>

</property>

</bean>

<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"/>

//spring自己的攔截器，測試

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)

    throws Exception {

System.out.println("*********************preHandle********************");

System.out.println(handler.getClass());

HandlerMethod handlerMethod = (HandlerMethod) handler;

System.out.println(handlerMethod.getMethod());

return true;

}

最終配置--------------------------------------------end

可能的錯誤

*********************preHandle********************
class com.chenzhou.examples.erm.web.AdminController
2012-10-21 16:28:25 org.apache.catalina.core.StandardWrapperValve invoke
嚴重: Servlet.service() for servlet erm threw exception
java.lang.ClassCastException: com.chenzhou.examples.erm.web.AdminController cannot be cast to org.springframework.web.method.HandlerMethod
    at com.chenzhou.examples.erm.util.interceptor.LoginInterceptor.preHandle(LoginInterceptor.java:37)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:891)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
……

 

    根據錯誤提示可以看出是HandlerMethod handlerMethod = (HandlerMethod) handler;這一步報錯了，根據System.out.println(handler.getClass());打印的結果可以得知handler是該請求訪問的Controller類，無法轉換成HandlerMethod對象。解決方案是使用

<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"> 
替換 
<bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping"/> 

因爲DefaultAnnotationHandlerMapping只能返回Controller對象，不會映射到Controller中的方法級別。替換之後配置如下：

 

<bean class="org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator" />
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"/>
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping">
    <property name="interceptors">
        <list>
            <bean class="com.chenzhou.examples.erm.util.interceptor.LoginInterceptor"/>
        </list>
    </property>
</bean>

 

    重啓tomcat測試之後發現再次報錯，報了另外一個錯誤，具體信息如下：

 

2012-10-21 16:39:39 org.apache.catalina.core.StandardWrapperValve invoke
嚴重: Servlet.service() for servlet erm threw exception
javax.servlet.ServletException: No adapter for handler [public org.springframework.web.servlet.ModelAndView com.chenzhou.examples.erm.web.AdminController.init(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)]: Does your handler implement a supported interface like Controller?
……

 

    這一次，請求根本沒有到達攔截器容器就已經報錯了，錯誤提示的意思是找不到handler對象對應的Adapter類。我在RequestMappingHandlerMapping類對應的spring-webmvc-3.1.0.RELEASE.jar 包裏找到了該類對應的Adapter類：RequestMappingHandlerAdapter