所以我创建了servlet并从Query字符串中获取了URL中的参数.
根据参数属性,调用了几个与Web服务相关的方法来获取文件详细信息和文件内容.现在调用servlet和用户系统之间的文件传输.
最大的担忧是,由于以下例外,代码片段工作正常.用户可以将文档保存在所需位置.我试图弄清楚为什么我会收到这个错误.
错误:
java.lang.IllegalStateException: getOutputStream() has already been called for this response at org.apache.catalina.connector.Response.getWriter(Response.java:611) at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:198) t DownloadServlet.doGet(DownloadServlet.java:99) at javax.servlet.http.HttpServlet.service(HttpServlet.java:617) at javax.servlet.http.HttpServlet.service(HttpServlet.java:723) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Thread.java:662)
代码## DownloadServlet.java
getDocument(HttpServletRequest request,HttpServletResponse response) { \\used Custom web services methods to get filename with extensions from external ECM system File resultFile = content.getAsFile(); response.setContentType("application/octet-stream"); ServletOutputStream outStream = response.getOutputStream(); try { response.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\""); byte[] byteBuffer = new byte[BUFSIZE]; DataInputStream in = new DataInputStream(new FileInputStream(file)); while ((in != null) && ((length = in.read(byteBuffer)) != -1)){ outStream.write(byteBuffer,0,length); } in.close(); outStream.flush(); } catch (Exception e) { e.printStackTrace(); }finally{ outStream.close(); } }使用Struts 2框架工作时,使用Web应用程序时遇到了同样的问题. 我搜索了一会儿,我找到的解决方案对我有用. 我找到了某个地方:
Basic rule of HTTP: one request, one response.
You can only send back one thing to a request. Either an HTML page, or a PDF document, or an image etc. Java complains if you have already obtained a writer/outputstream as you should only be getting ONE of these.
在我的例子中,下载文件的动作类在文件下载后向请求返回一个字符串“sucess”,这导致了问题.我将方法的返回类型更改为void并解决了问题.
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