简单的tcp/ip 协议java代码

//服务端
public class Server{
public static void main(String[] args) {
        //建立端口3500的服务器socket
        ServerSocket ss = null;
        try {
            ss = new ServerSocket(3500);
        } catch (Exception e) {
            e.printStackTrace();
        }
 //防止客户端断开以后服务端程序挂掉
        while (ss != null) {
            try {
                //在返回客户端socket以前，accept将会一直阻塞
                Socket s = ss.accept();//接收客户端的链接
                // 将请求指定一个线程去执行
                Thread start = new Thread(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            BufferedWriter wr = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
                            BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()));
                            int i = 0;
                            logger.debug("客户端已连接");
                            while (true) {
                                //发送信息时，须要加上换行符，不然客户端的readline()会阻塞
                                wr.write("服务器返回消息成功[" + i++ + "]\n");
                                //使用flush方法能够当即清空buffer，让消息立刻发出去，不然在buffer满以前消息都不会发出去
                                wr.flush();
                                String line = br.readLine();
                                logger.debug("来自客户端的数据：==" +line);

                            }
                        } catch (Exception e) {
//                            e.printStackTrace();
                            logger.debug("客户端已断开");
                        }
                    }
                });
                start.start();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

}
//客户端


public class Client {

    public static void main(String[] args) {
        try {
             Socket socket = new Socket("127.0.0.1", 3500);
//            Socket socket = new Socket("120.24.220.136", 3500);
            socket.setKeepAlive(true);
//            socket.setSoTimeout(10);
            BufferedWriter wr = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
            BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            int i = 0;
            boolean isOnline = true;
            while (isOnline) {
                //发送信息时，须要加上换行符，不然服务器端的readline()会阻塞
                wr.write("你好，您收到客户端的新年祝福[" + i++ + "]\n");
                //使用flush方法能够当即清空buffer，让消息立刻发出去，不然在buffer满以前消息都不会发出去
                wr.flush();
//                 socket.sendUrgentData(0xFF); // 发送心跳包  
                System.out.println("目前处于连接状态！");

                System.out.println("------------我是分割线------------");
                String line = br.readLine();
                System.out.println("来自服务器的数据：" + line);
                Thread.sleep(1000);
            }
        } catch (Exception ex) {
            Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}