1, 知识点介绍:
UDP:将数据及源和目的封装成数据包中,不需要建立连接每个数据报的大小在限制在64k内因无连接,是不可靠协议不需要建立连接,速度快。
UDP传输需要这些条件:
DatagramSocket与DatagramPacket
建立发送端,接收端。
建立数据包。
调用Socket的发送接收方法。
关闭Socket。
发送端与接收端是两个独立的运行程序。
发送端:
在我们编程中,我们需要明确的ip地址和端口号
DatagramSocket ds = new DatagramSocket();
byte[] by = “hello,udp”.getBytes();
DatagramPacket dp = new DatagramPacket(by,0,by.length,
InetAddress.getByName(“127.0.0.1”),10000);
ds.send(dp);
ds.close();
接收端:
在接收端,要指定监听的端口,就是DatagramSocket(里面的端口号);
DatagramSocket ds = new DatagramSocket(10000);
byte[] by = new byte[1024];
DatagramPacket dp = new DatagramPacket(by,by.length);
ds.receive(dp);
String str = new String(dp.getData(),0,dp.getLength());
System.out.println(str+"--"+dp.getAddress());
ds.close();
2,
我们 做了一个简单(UDP)的聊天程序
只要ip地址和端口号对应上,我们就能通过DatagramSocket,DatagramPacket,这两个类来发送和接收信息。
通过键盘录入获取要发送的信息。
将发送和接收分别封装到两个线程中。主函数1
其实这两个主函数1,2都是一样的,不同的端口号和ip(因为在一台电脑上测试,所有ip也是一样的)
/**
*
*/
package SampleDemo.UDP.chat.other;
import java.net.DatagramSocket;
import java.net.SocketException;
/**
* @author xinxin
*
*/
public class UdpDemo2 {
public static void main(String[] args) {
try {
DatagramSocket send2 =new DatagramSocket(9993);//不同的端口号记性匹配
DatagramSocket receive2 =new DatagramSocket(9994);
new Thread(new send(send2)).start();//线程启动
new Thread(new receive(receive2)).start();
} catch (SocketException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
package SampleDemo.UDP.chat.other;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
public class send implements Runnable {
DatagramSocket ds =null;
DatagramPacket dp =null;
public send(DatagramSocket ds) {
this.ds = ds;
}
@Override
public void run() {
BufferedReader br=null;
try {
br =new BufferedReader(new InputStreamReader(System.in));
String str=null;
while((str=br.readLine())!=null){
byte[] buf=str.getBytes();
dp=new DatagramPacket(buf, buf.length, InetAddress.getByName("192.168.31.158"), 9992);
ds.send(dp);
if("over".equalsIgnoreCase(str)){
break;
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
try {
br.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
主函数1的接收方
package SampleDemo.UDP.chat.other;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class receive implements Runnable {
DatagramSocket ds =null;
DatagramPacket dp=null;
public receive(DatagramSocket ds) {
this.ds = ds;
}
@Override
public void run() {
try {
while(true){
byte[] buf=new byte[1024];
dp=new DatagramPacket(buf, buf.length);
ds.receive(dp);
String id =dp.getAddress().getHostAddress();//获得ip 要负责任
int port=dp.getPort();//获得端口号
String str =new String(dp.getData(), 0, dp.getLength());
if("over".equalsIgnoreCase(str)){
System.out.println("对方离开了聊天室");
break;
}
System.out.println("ip:--"+id+",端口:"+port+"::"+str);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
ds.close();
}
}
}
主函数2
/**
*
*/
package SampleDemo.UDP.chat;
import java.net.DatagramSocket;
import java.net.SocketException;
/**
* @author xinxin
*
*/
public class UDPdemo {
/**
* @param args
*/
public static void main(String[] args) {
try {
DatagramSocket send1=new DatagramSocket(9991);
DatagramSocket receive1=new DatagramSocket(9992);
new Thread(new send(send1)).start();
new Thread(new receive(receive1)).start();
} catch (SocketException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
主函数2的发送方
/**
*
*/
package SampleDemo.UDP.chat;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.UnknownHostException;
/**
* @author xinxin
*
*/
public class send implements Runnable {
DatagramSocket ds =null;
public send(DatagramSocket ds) {
this.ds = ds;
}
@Override
public void run() {
//从键盘收字符
BufferedReader br=null;
try {
br =new BufferedReader(new InputStreamReader(System.in));
String str ="";
while((str=br.readLine())!=null){
byte[] buf=str.getBytes();//接收到数据之后变成字符数组封装于包
DatagramPacket dp =new DatagramPacket(buf, buf.length, InetAddress.getByName("192.168.31.158"), 9994);
ds.send(dp);
if("over".equalsIgnoreCase(str)){
break;
}
}
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
try {
br.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
主函数的接收方
package SampleDemo.UDP.chat;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class receive implements Runnable {
DatagramSocket ds=null;
public receive(DatagramSocket ds) {
this.ds = ds;
}
@Override
public void run() {
byte[] buf =new byte[1024];
DatagramPacket dp =new DatagramPacket(buf, buf.length);
while(true){
try {
ds.receive(dp);
//收到之后,然后从包里面获取所有的数据
String id=dp.getAddress().getHostAddress();//必须获得id,不然会负责法律责任
int port=dp.getPort();
String str=new String(dp.getData(), 0, dp.getLength());
if("over".equalsIgnoreCase(str)){
System.out.println("对方离开了聊天室");
break;
}
System.out.println("id="+id+",port"+port+",接收到的内容----"+str);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}}
}
}