File download servlet

[C Vivek]

Hi All,
Im trying to create a simple download servlet and try to retrieve from a html link. Upon clicking the link I only get a black DownloadServlet.do page opened.
Im trying to download the erp.pdf file which is placed direcly under the root directory.

Here's my servlet code:

  
 
package com.icore.download;
 
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileNotFoundException;
import java.io.*;
 
 
public class Download extends HttpServlet {
 
/**
 * The doGet method of the servlet. <br>
 *
 * This method is called when a form has its tag value method equals to get.
 * 
 * @param request the request send by the client to the server
 * @param response the response send by the server to the client
 * @throws ServletException if an error occurred
 * @throws IOException if an error occurred
 */
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException, FileNotFoundException  {
 
 response.setContentType("application/pdf");
 ServletContext ctx = getServletContext();
 InputStream is = ctx.getResourceAsStream("/erp.pdf");
 
 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 erp.pdf file is placed directly under root directory. 
 

web.xml description is as follows

   
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4" 
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee   
<a href="http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">" target="_blank" rel="nofollow">http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"></a>
  
  
<servlet> 
     <servlet-name>Download</servlet-name> 
     <servlet-class>com.icore.download.Download</servlet-class> 
     </servlet> 
<servlet-mapping> 
     <servlet-name>Download</servlet-name> 
     <url-pattern>/DownloadServlet.do</url-pattern> 
 </servlet-mapping> 
 
</web-app>
 
 

the url link is :

  
<a href="/DownloadServlet.do"> Download here</a>
 
  

Thanks in advance for you help.

[ September 28, 2008: Message edited by: Bear Bibeault ]

[ September 28, 2008: Message edited by: C Vivek ]
[ September 28, 2008: Message edited by: Bear Bibeault ]

[Satish Chilukuri]

I think the problem is here:

<a href="/DownloadServlet.do"> Download here</a> 

The path should not have a forward slash, else it will be treated as absolute path and not relative. It should be:

<a href="DownloadServlet.do"> Download here</a> 

[C Vivek]

Thanks, but i still have a problem I hope you can help.
The following code shows me a blank page "http://.../DownloadFile.do?filename=erp" if I use IE but works file with Firefox or Google Chrome.

The problem is that the users of the Intranet site im makinf use IE only.

I have ensured though that the file path is right( It gives a NullPointerException otherwise)

Would be grateful for your reply.


link

    <a href="DownloadFile.do?filename=erp"> 

servlet mapping in web.xml

 <servlet> 
     <servlet-name>Download</servlet-name> 
     <servlet-class>com.icore.download.Download</servlet-class> 
     </servlet> 
<servlet-mapping> 
     <servlet-name>Download</servlet-name> 
     <url-pattern>/DownloadFile.do</url-pattern> 
 </servlet-mapping> 
 
   

and the servlet code

  package com.icore.download;
 
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
 
 
public class Download extends HttpServlet {
 
/**
 * 
 */
private static final long serialVersionUID = -1292621693229536247L;


 
/**
 * The doGet method of the servlet. <br>
 *
 * This method is called when a form has its tag value method equals to get.
 * 
 * @param request the request send by the client to the server
 * @param response the response send by the server to the client
 * @throws ServletException if an error occurred
 * @throws IOException if an error occurred
 */
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException  {

 String filename = request.getParameter("filename");
 String file = "/"+filename+".pdf";
 System.out.println(file);
 
 response.setContentType("application/pdf");
 
 ServletContext ctx = getServletContext();
 InputStream is = ctx.getResourceAsStream(file);
 
 System.out.println(is.toString());
 int read =0;
 
 byte[] bytes = new byte[1024];
 OutputStream os = response.getOutputStream();
 
 while((read = is.read(bytes)) != -1)
 {
 
    os.write(bytes, 0, read);
  
 }
 System.out.println(read);
 os.flush();
 os.close();
 
 
}
}
  

[ September 28, 2008: Message edited by: C Vivek ]

[Ulf Dittmer]

I think IE tries to get the file type from the URL, and gets confused if there isn't any. (I know, it should use the content type header, but for some reason it doesn't. That's IE for you.) Try to make the URL look like a PDF file URL by appending "&iehack=.pdf" to it. I've seen other software packages do that successfully.

[C Vivek]

Im guilty of not looking around other threads before posting. Thought before anybody makes an effort to reply, I should inform ranchers that the problem is resolved.
I just had to add content-dispostition in the reponse header.(which I found in one of the previous posts)

Thank you Javaranch!

[C Vivek]

Thanks Ulf!! That worked smoothly too.

I have just used content-disposition in the response header to allow a download in the application.

[Bear Bibeault]

Originally posted by Satish Chilukuri:
It should be:

No. Page-relative paths are usually a big problem in web applications. If they work at all, they are fragile.

Rather, a context-relative path beginning with the / should be used. Please see the JSP FAQ entry on Resource URLs for more information.

[C Vivek]

Thanks Bear!
Changed the code accordingly.

[Anand Ramasamy]

C Vivek wrote:Thanks Bear!
Changed the code accordingly.

Hi,
I have different problem after using the "content-disposition: attachement" header.
The problem is after clicking the open button in the dialogue box, the adobe reader reports 'This file cannot be opened' error.
The browser I am using is IE6.
I have noticed the behaviour that the pdf file is stored inside the temporary intenet folder and it is getting deleted immediately after clicking on the open button.

I checked in many forums and the advice is to use "Cache-control: public","Cache-control: max-age=60".
But still it is not working for me.
And I hv tried many other combinations
like "Cache-control: private" and "Pragma: cache"
"Content-Type: application/pdf", "'Content-Length: file->size"
"Content-disposition: attachment; filename="'. file->filename"
"Expires: 0', 'Pragma: cache', 'Cache-Control: private"


But still it is not working. The application is running in Wesphere6.1
Please advice me some solution