Servlet for downloading a file

Question

i am writing a servlet for downloading a file on a GET action in the form..the web-xml is deployed correctly as far as i can interpret..bt i am encountering an error during the run time..
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
here is the log file..
Jul 11, 2008 12:07:14 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet DwnFile threw exception
java.lang.NullPointerException
     at com.example.web.dwnfile.doGet(dwnfile.java:17)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
it has some more content bt it is just the exceptions thrwn...
and here is my *.java file*
package com.example.web;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
public class dwnfile extends HttpServlet
public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException
response.setContentType("/image/jpeg");
ServletContext ctx=getServletContext();
InputStream is=ctx.getResourceAsStream("/2004.jpeg");
int read=0;
byte[] bytes=new byte[1024];
OutputStream os=response.getOutputStream();
while ((read=is.read(bytes))!=-1)
{os.write(bytes,0,read);
os.flush();
os.close();
the bold line is whre the exception is pointing..i think..
thanks in advance..
Edited by: Sun_Rockz on Jul 10, 2008 7:13 PM

Answer 1

response.setContentType("/image/jpeg");
ServletContext ctx=getServletContext();
InputStream is=ctx.getResourceAsStream("/2004.jpeg");there was an error in this part of code..the image extension of .jpeg is not allowed it seems..on changing it to jpg worked..and
in the first line the contenttype mst not be preceded by a forward slash..
now one more doubt relating to the same servlet..
response.setContentType("application/x-zip");
ServletContext ctx=getServletContext();
InputStream is=ctx.getResourceAsStream("/servlet_spec.zip");
if i keep this in my servlet the required action is taking place..i.e.i am gettin a download option bt the problem is tht the file is getting downloaded as a download.do file.....
download.do is the url pattern tht i am using in my html web page..
i tried replacing different types of allplications and files bt all are downloaded wit the same name. i.e. download.do
so what do u think is reason behind this..
thanks for all the replies.
Edited by: Sun_Rockz on Jul 11, 2008 10:47 AM
Edited by: Sun_Rockz on Jul 11, 2008 10:51 AM