public class IoEchoServer {

   public static void main(String[] args) throws IOException {
       ServerSocket serverSocket = new ServerSocket(7000);

       while (active) {
           Socket socket = serverSocket.accept(); // blocking

           InputStream is = socket.getInputStream();
           OutputStream os = socket.getOutputStream();

           int read;
           byte[] bytes = new byte[1024];
           while ((read = is.read(bytes)) != -1) { // blocking
               os.write(bytes, 0, read); // blocking
           }

           socket.close();
       }

       serverSocket.close();
   }
}