关于Filter中的两个异常,重定向后要加Return

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原地址:http://cuisuqiang.iteye.com/blog/1478086

关于Filter中的两个异常,重定向后要加Return

    博客分类:
  • J2EE
  • Java开源
  • Servlet/Jsp
filter过滤器j2eegoogleIllegalStateException

这是个很常见的问题,度娘和谷歌动手就能查到,可是今天还是遇到了,因为一直做业务研发,没有直接关注这些细节。

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这两个异常如下:

Java代码 复制代码 收藏代码
  1. java.lang.IllegalStateException: Cannot forward after response has been committed 
  2.     at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:313
  3.     at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301
  4.     at com.servlet.MyServlet2.doGet(MyServlet2.java:22
  5.     at javax.servlet.http.HttpServlet.service(HttpServlet.java:690
  6.     at javax.servlet.http.HttpServlet.service(HttpServlet.java:803
  7.     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290
  8.     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206
  9.     at com.filter.MyFilter.doFilter(MyFilter.java:48
  10.     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235
  11.     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206
  12.     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:228
  13.     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175
  14.     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128
  15.     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104
  16.     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109
  17.     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:216
  18.     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844
  19.     at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:634
  20.     at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:445
  21.     at java.lang.Thread.run(Unknown Source) 

Java代码 复制代码 收藏代码
  1. java.lang.IllegalStateException 
  2.     at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:407
  3.     at org.apache.catalina.servlets.DefaultServlet.serveResource(DefaultServlet.java:662
  4.     at org.apache.catalina.servlets.DefaultServlet.doGet(DefaultServlet.java:325
  5.     at javax.servlet.http.HttpServlet.service(HttpServlet.java:690
  6.     at javax.servlet.http.HttpServlet.service(HttpServlet.java:803
  7.     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290
  8.     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206
  9.     at com.filter.MyFilter.doFilter(MyFilter.java:48
  10.     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235
  11.     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206
  12.     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:228
  13.     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175
  14.     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128
  15.     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104
  16.     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109
  17.     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:216
  18.     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844
  19.     at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:634
  20.     at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:445
  21.     at java.lang.Thread.run(Unknown Source) 

只要在重定向后加return就可以了。

Java代码 复制代码 收藏代码
  1. public void doFilter(ServletRequest request, ServletResponse response, 
  2.         FilterChain chain) throws IOException, ServletException { 
  3.     request.setCharacterEncoding("UTF-8"); 
  4.     response.setCharacterEncoding("UTF-8");      
  5.     HttpServletRequest hrequest = (HttpServletRequest)request; 
  6.     String path = hrequest.getContextPath(); 
  7.     String basePath = hrequest.getScheme()+"://"+hrequest.getServerName()+":"+hrequest.getServerPort()+path+"/"
  8.     // 获得请求的全路径 
  9.     String reUrl = hrequest.getRequestURL().toString(); 
  10.     // 是否包含参数 
  11.     int index = reUrl.indexOf("?"); 
  12.     String re = ""
  13.     if(index == -1){ 
  14.         re = reUrl.substring(basePath.length()); 
  15.     }else
  16.         re = reUrl.substring(basePath.length(), index); 
  17.     } 
  18.     // 是否是请求资源 
  19.     if(!isResource(re)){ 
  20.         // 是否有访问的权限 
  21.         boolean isCheck = ConnUril.checkUrl(re); 
  22.         if(!isCheck){ 
  23.             request.getRequestDispatcher("/error.jsp").forward(request,response); 
  24.             // 必须加返回,否则报错 
  25.             return
  26.         } 
  27.     } 
  28.     // 继续执行 
  29.     chain.doFilter(request, response); 

报错原因很简单,转向后再去执行关于response的操作,就等于执行了两遍转向,因此会报错!

问题简单,也需要留意,再简单的问题也是问题,成功在细节和那些别人以为是傻冒的问题中。

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