Java :: Putting Short Into 2 Bytes Of String

So I'm making my own networking protocol for a online game, to save space each message (sent over TCP) is given a ID which is a short, 2 bytes, all messages sent from the server to the client and vice versa are strings, how can I convert a short to a string in java in just 2 bytes (characters)? I want to be able to convert a short int into 2 characters, so that I can send the short over the network in a string format in just 2 bytes and decode it back into a short on the other side (in actionscript 3). A character can hold 256 possible values right? So 256*256=65,536 which is the size of a unsigned short int!

Here's what I've got so far:
public static String toCode(int c){
if(c <= 255 ){
return Character.toString((char)c);
}else{
return null;
}}
public static int fromCode(String c){
return ((int)c.charAt(0));//Return the character code of the send string, 1 char only
}

This can turn a int into a single character which can be sent over the network, now I just need to have it use 2 characters and it can do up to a short.