Controlling HTTP Response Header Lines

Part:   1  2  3  4  5  6  7 

(Continued from previous part...)

Another way of sending non-HTML data to the client is via attachment. The following JSP will show you how to do this:

<?xml version="1.0"?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="1.2">
<!-- Download.jsp
     Copyright (c) 2002 by Dr. Herong Yang
-->
<jsp:directive.page session="false" import="java.io.*" />
<jsp:scriptlet>
   String p = request.getQueryString();
   boolean ok = true;
   ok = p!=null;
   if (ok) {
      if (p.indexOf(".html")>-1) {
         response.setContentType("text/html");
      } else if (p.indexOf(".gif")>-1) {
         response.setContentType("image/gif");
      } else if (p.indexOf(".pdf")>-1) {
         response.setContentType("application/pdf");
      } else if (p.indexOf(".doc")>-1) {
         response.setContentType("application/msword");
      } else {
         ok = false;
      }
   }
   if (ok) {
      response.setHeader("Content-disposition", 
         "attachment; filename="+p);
      try {
         int l = (int) new File(p).length();
         response.setContentLength(l);
         byte[] b = new byte[l];
         FileInputStream f = new FileInputStream(p);
         f.read(b);
         ServletOutputStream o = response.getOutputStream();
         o.write(b,0,l);
         o.flush();
         o.close();
         f.close();
      } catch (Exception e) {
         ok = false;
      }
   }
   if (!ok) {
      response.sendError(HttpServletResponse.SC_BAD_REQUEST);
   }
 </jsp:scriptlet>
</jsp:root>

In this page, anther header line, "Content-disposition", is added to the response, in which I am telling the client program that the entity data is an attachment, with file name specified.

Now try to use IE to request: http://localhost:8080/Download.jsp?hello.pdf, you will see IE prompting you to save the attachment instead of calling Adobe Reader to display the data.

IE 6.0 Bug on Display PDF Data

While I was trying to display PDF data, I found that IE 6.0 is not responding correctly to Content-Type: application/pdf. Here is a sample JSP, GetPdf.jsp, to show the problem.

<?xml version="1.0"?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="1.2">
<!-- GetPdf.jsp
     Copyright (c) 2002 by Dr. Herong Yang
-->
<jsp:directive.page session="false" import="java.io.*" />
<jsp:scriptlet>
   String p = "hello.pdf";
   response.setContentType("application/pdf");
   try {
      int l = (int) new File(p).length();
      response.setContentLength(l);
      byte[] b = new byte[l];
      FileInputStream f = new FileInputStream(p);
      f.read(b);
      ServletOutputStream o = response.getOutputStream();
      o.write(b,0,l);
      o.flush();
      o.close();
      f.close();
   } catch (Exception e) {
      response.sendError(HttpServletResponse.SC_BAD_REQUEST);
   }
 </jsp:scriptlet>
</jsp:root>

If you use IE 6.0 to request: http://localhost:8080/GetPdf.jsp, you will get nothing on the IE window.

Now if you use IE 6.0 to request: http://localhost:8080/GetPdf.jsp?x.pdf, you will see Adobe Reader displaying the hello message.

Interestingly, if you use IE 6.0 to request: http://localhost:8080/GetPdf.jsp?x.doc, you will also see Adobe Reader displaying the hello message.

I guess IE 6.0 has a stupid bug. What do you think?

Part:   1  2  3  4  5  6  7