基于UDP的服务器实现多线程时，第一个客户运行端不能在服务器登陆得到响应，第二个实行客户端，第一次执行已停止的客户端才能接受服务器的响应，服务器也才会得到第一个客户端的信息
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;
public class UDPCilent {
public static void main(String[] args) {
try {
/*
* 向服务器端发送信息
*/
//定义服务器ip，端口，信息
InetAddress address=InetAddress.getByName("localhost");
int port=8000;
byte []data="用户名：kuerban;密码：668858".getBytes();
//建立DatagramPacket
DatagramPacket packet=new DatagramPacket(data, 0, data.length, address, port);
//建立DatagramSocket
DatagramSocket socket=new DatagramSocket();
socket.send(packet);
/*
* 获取服务端发送信息
*/
//建立数据包接受信息
byte bytes[]=new byte[1024];
DatagramPacket packet1=new DatagramPacket(bytes, bytes.length);
socket.receive(packet1);
String info=new String(bytes, 0, packet1.getLength());
System.out.println(info);
socket.close();
} catch (UnknownHostException | SocketException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
/*
* 服务器端，基于UDP实现用户登录
*/
public class UDPServer {
public static void main(String[] args) {
try {
/*
* 接受信息
*/
//建立一个DatagramSocket,指定端口
DatagramSocket socket=new DatagramSocket(8000);
byte []bytes=new byte[1024];
//建立一个Datagrampacket，以接受数据
DatagramPacket packet=new DatagramPacket(bytes, bytes.length);
/*
* 发送数据
*/
//启动服务器
System.out.println("服务器已启动");
while(true){
socket.receive(packet);
//建立客户端ip，端口
InetAddress address=packet.getAddress();
int port=packet.getPort();
UDPthread thread=new UDPthread(socket,packet,address,port,bytes);
thread.start();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
public class UDPthread extends Thread{
DatagramPacket packet=null;
InetAddress address=null;
byte bytes[];
int port=0;
DatagramSocket socket=null;
public UDPthread(DatagramSocket socket,DatagramPacket packet,InetAddress address,int port,byte[] bytes) {
this.packet =packet;
this.address=address;
this.port=port;
this.socket=socket;
this.bytes=bytes;
}
public void run(){
//读取信息,输出信息
String info=new String(bytes, 0, packet.getLength());
System.out.println(info);
//建立信息，并发送
byte bytes1[]="登陆成功".getBytes();
DatagramPacket packet1=new DatagramPacket(bytes1, 0, bytes1.length,address,port);
//向客户端响应
try {
socket.send(packet1);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
0是offset是从第几个byte开始的