Create a new file on server from an applet

Question

Hello!
I 'm trying to create a text file on server from an applet, i have permissions to write on server and i'm running in apache, my code is
public void write () {
try{
URL url = new URL("http://localhost/bnm/hello.txt");
URLConnection urlcon = url.openConnection();
urlcon.setDoOutput(true);
urlcon.setUseCaches(true);
PrintWriter pt = new PrintWriter
(new OutputStreamWriter (urlcon.getOutputStream()));
String str = new String(URLEncoder.encode("this is output applet ")) ;
pt.print(str);
pt.flush();
catch(Exception e)
e.printStackTrace();
The result is nothing, the file isn�t created, but the code don't throw exceptions.
Ah! in other example, i can read a file of server fro m the applet, the problem is to write
Anybody, knows the matter??
Excuse my poor english :P
Thanks for all.

Answer 1

I had the same needs and didn't know whether this was possible, due to applets security restriction. So I searched the Web and found some contradictory information. I will explain what I think is the situation, to give you an answer, but also so that other people can tell me whether I understood correctly.
1) Unless you sign it, an applet cannot write files directly, either client-side or server-side. All what it can do to access a file server-side (except .jar files ?) is opening a http connection, which allows only to retrieve data. When I try to run code such as yours, I get this exception :
java.net.UnknownServiceException: protocol doesn't support output
     at java.net.URLConnection.getOutputStream(URLConnection.java:679)
2) As Ares_Man points out, what it can do is opening a http connection not directly with the file you want, but with a server-side script (JSP, PHP, CGI,...) which will be allowed to write files on the server. You can use POST or GET parameters to pass to the script what you are going to write.
This simple code worked for me (it executed the script toto.php):
          try{
               URL toto=new URL(getCodeBase(),"toto.php");
               InputStream f=toto.openStream();
               f.close();
          catch(Exception e){
               e.printStackTrace();
Probably it's a good idea to do a URLConnection.setCache(false) though, to be sure that the script toto.php will be executed.
3) I don't know how you can pass serialized objects as parameters. So if more than text informations are to be written, I would tend to make the script store them into a database instead of files. That way, you could pass any SQL query as parameter, maybe along with a password parameter for security. I don't know whether this is secure enough.