Download and Upload using applet

Question

hi everyone,
i tried to develop an applet that can handle upload and download file from server to client and vice versa.
is there anyone can help me?
Please help.
thank you for replies.

Answer 1

You need to sign your applet and the user needs to trust this signature in order for the
applet to read from the local filesystem and or connect to a server other than the one the
applet came from.
http://forum.java.sun.com/thread.jsp?forum=63&thread=524815
second post
Here is some code that will upload (both msjvm and sun jre) but I never really finished
it. Note that if you use the applet with msjvm the client has to adjust java security in IE
import java.awt.*;
import java.net.*;
import java.io.*;
public class srvHead extends java.applet.Applet implements Runnable{
     String c = "";
     public srvHead(){
          new Thread(this).start();
     public void init(){
//          new Thread(this).start();
     public void run(){
          try{
// run this as an application first, when it works than make an applet of it
               URL u = new URL("http://localhost:101/test");
               URLConnection c = u.openConnection();
               // post multipart data
               c.setDoOutput(true);
               c.setDoInput(true);
               c.setUseCaches(false);
               // set some request headers
               c.setRequestProperty("Connection", "Keep-Alive");
// TODO: get codebase of the this (the applet) to use for referer
               c.setRequestProperty("HTTP_REFERER", "http://applet.getcodebase");
               c.setRequestProperty("Content-Type", "multipart/form-data; boundary=****4353");
               DataOutputStream dstream = new DataOutputStream(c.getOutputStream());
// write content to the server, begin with the tag that says a content element is comming
               dstream.writeBytes("--****4353\r\n");
// discribe the content, (in this case it's a file)
               dstream.writeBytes("Content-Disposition: form-data; name=\"myfile\"; filename=\"C:\\myFile.wav\"\r\nContent-Type: application/octet-stream\r\n\r\n");
// open a file
               String title = "Frame Title";
               Frame frame = new Frame("Select a file");
               FileDialog fd = new FileDialog(frame);
               frame.setSize(400, 400);
               fd.show();
               System.out.println(fd.getDirectory() + fd.getFile());
               File f = new File(fd.getDirectory() + fd.getFile());
               FileInputStream fi = new FileInputStream(f);
// keep reading 1000 bytes from the file
               byte[] bt = new byte[1000];
               int cnt = fi.read(bt);
               while(cnt==bt.length){
                    dstream.write(bt,0,cnt);
                    cnt = fi.read(bt);
// send the last bit to the server
               dstream.write(bt,0,cnt);
// now close the file and let the web server know this is the end of this form part
               dstream.writeBytes("\r\n--****4353\r\n");
// send a form part named TargetURL with the value: /IntranetContent/TelephoneGuide/Upload/
               dstream.writeBytes("Content-Disposition: form-data; name=\"TargetURL\"\r\n\r\n");
               dstream.writeBytes("/IntranetContent/TelephoneGuide/Upload/");
// let the web server know this is the end of this form part
               dstream.writeBytes("\r\n--****4353\r\n");
// send a form part named redirectURL with the value: http://none/none
               dstream.writeBytes("Content-Disposition: form-data; name=\"redirectURL\"\r\n\r\n");
               dstream.writeBytes("http://none/none");
// this is the last information part of the multi part request, close the request
// close the multipart form request
               dstream.writeBytes("\r\n--****4353--\r\n\r\n");
               dstream.flush();
               dstream.close();
               fi.close();
               try{
                    DataInputStream in =
                         new DataInputStream(
                              new BufferedInputStream(c.getInputStream()));
                    String sIn = in.readLine();
                    boolean b = true;
// TODO: this will loop forever unless you make sure your server page
// sends a last line like "I am done"
// than you can do wile(sIn.compareTo("I am done")!=0){
                    while(sIn!=null){
                         if(sIn!=null){
                              System.out.println(sIn);
                         sIn = in.readLine();
               }catch(Exception e){
                    e.printStackTrace();
          }catch(Exception e){
               e.printStackTrace();
     public static void main(String[] args) {
               new srvHead();
}