spring4mvc 實現檔案下載功能reponse.getOutputStream()重複呼叫問題解決
阿新 • • 發佈：2019-02-19
本來是準備做一個類似網路硬碟的功能，判斷目標是檔案的時候，點選就啟動下載。
誰想遇到了不少麻煩，最直接的麻煩就是遇到了response.getOutputStream()重複使用的異常。。雖然對功能沒有影響，但是這個報錯的異常始終看著不舒服，百度上搜索了一大圈，總是說什麼getWriter()和getOutputStream()只能二選一，因為我採用的是spring4管理，在JSP沒有任何jsp程式碼片段（實際上，就算是我加入了out.clean()兩行程式碼也無效）。
其實很簡單，只是自己以前沒有用spring框架的時候也遇到過，就是return null；就搞定了。
異常如下
八月 11, 2014 8:33:31 上午 org.apache.catalina.core.StandardWrapperValve invoke 嚴重: Servlet.service() for servlet [xchgx] in context with path [/HbouCn] threw exception [java.lang.IllegalStateException: getOutputStream() has already been called for this response] with root cause java.lang.IllegalStateException: getOutputStream() has already been called for this response at org.apache.catalina.connector.Response.getWriter(Response.java:636) at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:213) at javax.servlet.ServletResponseWrapper.getWriter(ServletResponseWrapper.java:104) at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125) at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118) at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:186) at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:126) at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:80) at org.apache.jsp.WEB_002dINF.views.manager.disk.main_jsp._jspService(main_jsp.java:166) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:748) at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:604) at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:543) at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:201) at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:267) at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1221) at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1005) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:952) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852) at javax.servlet.http.HttpServlet.service(HttpServlet.java:620) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)
出錯的程式碼：
最後決定就加了一句話就搞定了。害我折騰了2天。/** * 根據type判斷為檔案，就啟動下載 * @param path 檔名 * @param request * @param response * @throws IOException */ @RequestMapping(value="next",method=RequestMethod.GET,params = "type=1") public ModelAndView download(@RequestParam(value="path") String path,HttpServletRequest request,HttpServletResponse response) throws IOException{ //這裡要轉換，不論你是否在tomcat下的server.xml做過修改，還是在JSP中加入response.setCharacter("UTF-8"); //或request.....UTF-8都沒用，包括spring-servlet.xml和web.xml加入encoding utf-8過濾器都無效，這裡一定要加這一句話才能識別中文。 <pre name="code" class="java"> String nPath = new String(path.getBytes("ISO-8859-1"),"UTF-8"); String parentPath = (String) getSessionObject(request, CommonConstant.CURRENT_DIRECTORY); String filePath = diskService.getNextDirectory(parentPath, nPath); diskService.download(filePath,request,response); return new ModelAndView("manager/disk/main"); }
/** * 根據type判斷為檔案，就啟動下載 * @param path 檔名 * @param request * @param response * @throws IOException */ @RequestMapping(value="next",method=RequestMethod.GET,params = "type=1") public ModelAndView download(@RequestParam(value="path") String path,HttpServletRequest request,HttpServletResponse response) throws IOException{ String nPath = new String(path.getBytes("ISO-8859-1"),"UTF-8"); String parentPath = (String) getSessionObject(request, CommonConstant.CURRENT_DIRECTORY); String filePath = diskService.getNextDirectory(parentPath, nPath); diskService.download(filePath,request,response); <span style="color:#FF0000;">return null;</span>//媽的原來返回一個null就搞定了response重複呼叫的問題，害死我了。 }
做個筆記，防止忘記