I'm not sure if I quite understand you, but I think one or the other will apply:
If the server is returning a URL to your applet, you can parse it using the java.net.URL class for the major components, at least. As for breaking down the operands, you might just want to see if you have source for the javax.servlet.HTTPRequest class (I'm not sure that's quite the right name and package, but something like that). If you do, you could either plunder its code or find out what utility package it's using.
URL parameter encoding isn't real complex - just a bunch of operands separated by "&" with spaces replaced by "+" and more complex characters gicen by "%" followed by a hex code. So you could split the operands with the
java text parser class, use the
String character subsitution class to change the "+" to space and the only really hard stuff would be the hex codes. But it's reinventing the wheel, so
you should try my first suggestion and/or google for a "Java URL decoder".
More common for servlets is that they make up a URL request to a server via class HttpURLRequest and et the answer back as a stream. If you're NOT using the URLRequest class, you really should be, since it also handles the HTTP headers (including cookies for session info) automagically. Using raw socket I/O is more trouble and more stuff you have to debug. The returned stream is just that - a data stream, and is commonly lines of text or XML, though anything allowable as long as it can make it over HTTP.