java socket－TCP连接

package test;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketAddress;


public class GprsServer {
    public static Socket socket;
    public static ServerSocket ss=null;
    public static DataInputStream in;
    public static DataOutputStream out;
    public static final int PORT=8100;


    public static void main(String arg[])
    {
        try
        {
            SocketAddress remoteAddr=new InetSocketAddress(PORT);
            ss = new ServerSocket();
            ss.bind(remoteAddr);//以上两句可用 ss = new ServerSocket(PORT);
            socket=ss.accept();//等待客户端连接，会阻塞进程
            in=new DataInputStream(socket.getInputStream());
            out=new DataOutputStream(socket.getOutputStream());
            while(true)
            {
                if(!socket.isConnected())
                {
                    socket=ss.accept();//等待获取数据
                    in=new DataInputStream(socket.getInputStream());
                    out=new DataOutputStream(socket.getOutputStream());
                }
                byte[] result=new byte[712];
                byte wel[]=new byte[50];
                in.read(result);//会阻塞进程
                System.arraycopy(result,0,wel,0,14);
                String str=new String(wel,0,3);//若发送的字符长度小于数组长度，需限制转为string的长度，否则转换的成string有误
                System.out.println("接收数据："+str);
                out.write(wel);
                System.out.println("发送数据："+str);
                if(str.equalsIgnoreCase("bye"))
                    break;
            }
            System.out.println("close!");
            socket.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
}

 TCP Socket服务端，监听本地端口。客户端需要知道服务端的IP和端口