java.lang.IllegalStateException: Already using out

windchill GUI on client side browser when a user clicks on a button particular pdf file should gets downloaded on his system.I have achieved this by using the following code.

   <body>
    <%
    String pdfname=   session.getAttribute("pdfname").toString();
    String Pdfpath=   session.getAttribute("pdfpath").toString();
    File f =new File(Pdfpath);
     Boolean flag=false;
      if(f.exists())
      {
     BufferedInputStream filein = null;
     BufferedOutputStream out2=null;
    try {
    File file = new File(Pdfpath);//specify the file path
    byte b[] = new byte[1048576];
    int len = 0;
    filein = new BufferedInputStream(new FileInputStream(file));
    out2=new BufferedOutputStream(response.getOutputStream());
    response.setHeader("Content-Length", ""+file.length());
    response.setContentType("application/pdf");
    response.setHeader("Content-Disposition","attachment;filename="+pdfname);
    response.setHeader("Content-Transfer-Encoding", "binary");
    while ((len = filein.read(b)) > 0) {
    out2.write(b, 0, len);
    out.println("Your Pdf Document Is Generated Please close it");
    }
    filein.close();
    out2.flush();
    out2.close();
  }
    catch(Exception e)
{
    out.println(e);
    }

      }else{

        String error ="File Not Found Or File Has Bean Deleted Already";
        request.setAttribute("error", error);
        RequestDispatcher s = request.getRequestDispatcher("NoFile.jsp");
                s.forward(request, response);
    }
     %>
    </body>

This code works fine and file is getting downloaded but after that It throws an exception.The following is my method server log

ERROR : org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/Windchill].[jsp]  - Servlet.service() for servlet jsp threw exception
Thu 3/28/13 12:29:07: TP-Processor7: java.lang.IllegalStateException: Already using output stream
Thu 3/28/13 12:29:07: TP-Processor7:    at wt.servlet.CompressionFilter$GzippingResponse.getWriter(CompressionFilter.java:860)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.jasper.runtime.JspWriterImpl.flush(JspWriterImpl.java:173)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.jasper.runtime.JspWriterImpl.close(JspWriterImpl.java:187)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.jsp.netmarkets.jsp.gt.get_jsp._jspService(get_jsp.java:105)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
Thu 3/28/13 12:29:07: TP-Processor7:    at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
Thu 3/28/13 12:29:07: TP-Processor7:    at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
Thu 3/28/13 12:29:07: TP-Processor7:    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
Thu 3/28/13 12:29:07: TP-Processor7: ......

......

There are lots of post available in google regarding this exception but I can't clear my mistake. I've also tried adding this in servlet instead of jsp. That too shows the same exception.Is this way correct for downloading a file or I'm in wrong way? I need help

Thanks

回答1:

You cannot use both getServletOutputStream() and getWriter() in same response.

Coming to your problem. Avoid writing scriptlets in JSP. Whatever you are doing in JSP , implement it in Servlet.

You are calling response.getOutputStream(); in JSP which is illegal. You should use either ServletResponse.getOutputStream() or ServletResponse.getWriter(). Since JSP's use ServletResponse.getWriter() by default. You should write to ServletResponse.getWriter() instead ServletResponse.getOutputStream()

This is what Java Doc says :

getOutputStream...

ServletOutputStream getOutputStream() throws IOException

Returns a ServletOutputStream suitable for writing binary data in the response. The servlet container does not encode the binary data.

Calling flush() on the ServletOutputStream commits the response. Either this method or getWriter() may be called to write the body, not both.

Returns: a ServletOutputStream for writing binary data Throws: IllegalStateException - if the getWriter method has been called on this response

回答2:

Seems like the exception is thrown from this line.

out.println(e);

In case your code to send the PDF as Application fails during writing then it will thrown and exception and while trying to print the exception with the above line the outputputstream is already being used.

Do not intermix UI and Business Logic in JSP. Use a Servlet to do this job.

回答3:

You have </body> after your scriptlet. It'll print something to the response outputstream, but you have already closed that one before.

What sense does it make to include <body> tags in your response when what you actually want to do is stream a PDF back to the client?