简单实用的java socket服务端和客户端代码

 服务端：
package socket;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
public class Server {
 public static void main(String[] args) {
  try {
   ServerSocket server = new ServerSocket(21002);
   System.out.println("正在监听端口:21002");
   while (true) {
    Socket socket = server.accept();
    System.out.println("客户端:" + socket+"进入");
    BufferedInputStream in = new BufferedInputStream(socket.getInputStream());
    BufferedOutputStream  out = new BufferedOutputStream(socket.getOutputStream());
    byte[] b = new byte[10240];
    in.read(b);
    System.out.println("接收到客户端的数据："+new String(b));
    out.write(b);
    out.flush();
    out.close();
    in.close();
    socket.close();
    System.out.println("客户端:" + socket+"离开");
   }
  } catch (Exception ex) {
   ex.printStackTrace();
  }
 }
}
客户端：package socket;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.net.Socket;
public class Client {
 /**
  * @param args
  * @throws InterruptedException
  */
 public static void main(String[] args){
  try {
   Socket socket = new Socket("127.0.0.1", 21002);
   BufferedInputStream in = new BufferedInputStream(socket.getInputStream());
   BufferedOutputStream  out = new BufferedOutputStream(socket.getOutputStream());
   out.write("test".getBytes());
   out.flush();
   byte[] b = new byt