Downloading Multiple Files

Hi,

I want to download multiple files on a http request. I am aware that i can zip all the files and then download the zip as a single file.

Are there any other options (like AJAX or applets) that could achieve this?

How does sun download manager download files?

Thanks,

Srikanth,
By definition, you can download one thing at a time. The choices are zipping it up (which you've considered) or downloading them one at a time. AJAX or Applets could provide different graphical options for downloading one at a time, but does not change the underlying architecture.

Jeanne,

My requirement says: I have to download 10 files in response to an HTTP Request.
For each file the browser has to display save dialog box(10 times). This all should happen in a single HTTP Request. My requirements doesn't want to zip the files. Is there any way to achieve this?

Can i say this requirement is not feasible to my Business Analysts.

Thanks in Advance,

Has your BA seen this done?
If the response can contain multi-part data, then you could put content-type, content-length and content-disposition response fields along with the data in the response. My HTML text discusses it under "Server-Push"

Originally posted by Srikanth Reddy:
Is there any way to achieve this?

No

Can i say this requirement is not feasible to my Business Analysts.[?][/QB]

The analyst should have had a technical consultant in the room before he decided this.

That being said, you might be able to make it appear that you have achieved this with Javascript and iframes.
Would you like me to move this to our HTML/Javascript forum?

Originally posted by Norm Radder:
Has your BA seen this done?
If the response can contain multi-part data, then you could put content-type, content-length and content-disposition response fields along with the data in the response. My HTML text discusses it under "Server-Push"

Could you please point me to some sample code.

Sorry, I only have printed text (HTML4.0 Sourcebook by Ian Graham) and no code examples. The text implies that a server can send multiple files to a browser that will cause the browser to prompt the user to save each file.
Try Searching for multipart and Server-push

Just to verify the above is possible I wrote a Q&D servlet for "my HTTP server" to demo multiple file down loads. I was able to get the browser to prompt for and save two files with a single HTTP GET with the following code:

package servlets;
 
import java.io.*; 
import javax.servlet.*; 
import javax.servlet.http.*; 
 
 public class Servlet_multipart extends HttpServlet { 
 
    final boolean verbose = true;
 
    public void doGet(HttpServletRequest req, HttpServletResponse  res) 
                            throws ServletException, IOException{ 
 
      final byte[] CRLF = new byte[]{(byte)'\r', (byte)'\n'};
      String boundaryTxt = "--AMZ90RFX875LKMFasdf09DDFF3";
      String fileName = "Servlet_multipart"; 
 
      res.setContentType("multipart/x-mixed-replace;boundary=" + boundaryTxt.substring(2));
 
     // Read from file into servlet output stream
     ServletOutputStream stream = res.getOutputStream();
 
     byte[] boundary = boundaryTxt.getBytes();
     stream.write(boundary, 0, boundary.length);  // write the first boundary
     stream.write(CRLF, 1, 1);         // pls LF
     byte[] contentType = "Content-type: text/plain\n".getBytes();
 
     // Write out a couple of files
     for(int i = 0; i < 2; i++) {
        stream.write(contentType, 0, contentType.length);
        byte[] contDisp = ("Content-Disposition: attachment; filename=" 
                                    + fileName + i + "\r\n\r\n").getBytes(); // blank line follows
        stream.write(contDisp, 0, contDisp.length);
            
        // Lets read this file???
        BufferedInputStream fif = new BufferedInputStream(
                       new FileInputStream("D:\\JavaDevelopment\\runtime\\CheckClassRefs.ini")); 
        
        if (verbose) System.out.println("Sending file " + i + " to client as '" + fileName + i +"'");
        int data = 0; 
        int  byteCnt = 0;
        while((data = fif.read()) != -1) { 
            stream.write(data);
            byteCnt++;
        } 
        fif.close(); 
        stream.write(boundary, 0, boundary.length);  // write bndry after data
        stream.write(CRLF, 1, 1);  // plus LF
        if (verbose) System.out.println("Finished sending file " + i +". " + byteCnt + " bytes");
     } // end for(i)  outputing files
 
     byte[] endBndry = (boundary + "--").getBytes();
     stream.write(endBndry, 0, endBndry.length);  // write the ending boundary
     stream.close(); 
    } 
} // end class

[ July 03, 2008: Message edited by: Norm Radder ]

line 52 :

byte[] endBndry = (boundaryTxt + "--").getBytes();

instead of

byte[] endBndry = (boundary + "--").getBytes();

It's work better, because you were confounding byte and string.

Good Work really nice piece of code

The problem is that IE don't implements "multipart/x-mixed-replace"...

What's it can be a solution to IE? Create a Zip file?

I don't think it is a problem.

First you shoul have the zip process ablility in the server size, then zip the files you want to send to the client, then open a binary output stream to transfer it.

That is all. what more J2SE include the ability to zip files.

Yes, I have done it...

The files are generated by the JasperReports, then I just got the OutputStream of each one and wrote it in the ZipOutputStream... Very simple.

Thanks...