Java telnet server send data,string with other key rather than "ENTER"

Question

i'm making a java telnet server. The client is the windows telnet. I'm stuck at the sending data,string with other key rather than "ENTER" key. E.g: Hello, i'm user 1. after "user 1" when the full stop is typed it should send that code:

byte[] buff = new byte[4096];
String str = new String(buff, "UTF-8");
do {
    if ( buff[0] == 46 ) {  //46-[.]
        System.out.println("46-[.]  " + buff[0]);
        //incoming.getInputStream().read(buff);
    }
    incoming.getInputStream().read(buff);
} while ((buff[0] != 27) && (!done));

Answer 1

I believe the problem is your code here. This code would never work.

byte[] buff = new byte[4096];
String str = new String(buff, "UTF-8"); //the buffer is initialized to 0 so we get no String
do {
    if ( buff[0] == 46 ) {  //46-[.]
        System.out.println("46-[.]  " + buff[0]);
        //incoming.getInputStream().read(buff);
    }
    incoming.getInputStream().read(buff);   //reading into an array
} while ((buff[0] != 27) && (!done));       //and only checking first index

Try this and see if it works.

public static void main(String[] args) throws IOException {
    //listen on tcp port 5000
    ServerSocket ss = new ServerSocket(5000);
    Socket s = ss.accept();

    //create an input/output stream
    InputStream in = new BufferedInputStream(s.getInputStream());
    PrintWriter out = new PrintWriter(s.getOutputStream(), true);

    byte[] buffer = new byte[0x2000];
    for (int bufferlen = 0, val; (val = in.read()) != -1;) {
        if (val == '.') { //if token is a '.' no magic numbers such as 46
            String recv = new String(buffer, 0, bufferlen);
            System.out.printf("Received: \"%s\"%n", recv);
            bufferlen = 0; //reset this to 0
        } else if (val == 27) {
            s.close();
            break;
        } else { //character is not a . so add it to our buffer
            buffer[bufferlen++] = (byte)val;
        }
    }
    System.out.println("Finished");
}

when you run it do telnet localhost 5000 from the same computer. Windows telnet will send every time you press a key, so this will work with windows telnet not linux. You have to remember that TCP is stream based, unlike UDP which is packet based. I have tested this with Windows Command Prompt, so I don't know which one you are using if it doesn't work.