How to update content of a file on server using a Java Applet?

Question

Hi,
I'm new to Java, and I have a task now to overwrite a text file on a server using an applet. I have written a piece of code which compiles but doesn't work. Can you please take a look at the code or give me another way to do it?
Thanks.
Code:
import java.applet.Applet;
import java.io.*;
import java.net.*;
public class test2 extends Applet{
public void init() {
StringBuffer buf = new StringBuffer();
try {
     String output = "this is some string";
     URL aUrl = new URL (getCodeBase().toString() + "test.txt");
     System.out.println(aUrl);
     URLConnection con = aUrl.openConnection();
     con.setDoOutput(true);
     PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(con.getOutputStream())));
     out.println(output);
     out.close();
catch (MalformedURLException mue) {
     System.out.println("improper url");
     mue.printStackTrace();
catch (IOException e) {
     System.out.println("io exception");
     e.printStackTrace();
}

Answer 1

Ram.ViSolve wrote:
869975 wrote:
Thanks. I knew there would be a security issue, but I do not have sufficient knowledge to get around it. If you have a reference how to configure a server please post it here.You need to create Signed Applet. Because normally applets have some restriction to access the files in the client machine. Signed applets overrides the restriction.
To know more, Read [url http://192.9.162.55/developer/onlineTraining/Programming/JDCBook/signed.html]Signed Applet
No. Our OP wants to write to the server, not to the client! And to achieve this from an applet, you don't need it signed, iff the server is the machine from where the applet was downloaded in the first place. You only need to use a mechanism that allows you to write to servers, which HTTP is not. FTP, on the other hand, if setup properly can do it. So instead of trying to write using an HttpURLConnection (OP's attempt), you would use an FTP client library. FTP here is just an example and probably not the best way. Another option is to use some servlet or PHP or ASP on the server side and the applet will sumbmit the changes to that code on the server, which in turn will write to the file. The idea is that you need some 'partner code' on the server, be it the FTP server or the servlet/PHP/ASP code. None of this requires the applet to be signed.