java UDP
java中UDP的实现氛围两个类:DatagramPacket 和 DatagramSocket
DatagramPacket类将数据填充到UDP包中,这称为数据报,有你来解包接受的数据报.
DatagramSocket可以收发UDP数据报,为收发送数据要将数据放到DatagramPacket中
两个参数的构造器用于接收数据报
四个参数的构造器用于发送数据报
一.客服端
java编程思想UDP client实例
package test; import java.net.*; public class Dgram { public static DatagramPacket toDatagram( String s,InetAddress destIA,int destPort){ byte[] buf = new byte[s.length() + 1]; buf = s.getBytes(); return new DatagramPacket(buf,buf.length,destIA,destPort); } public static String toString(DatagramPacket p){ return new String(p.getData(),0,p.getLength()); } } //: ChatterClient.java // Tests the ChatterServer by starting multiple // clients, each of which sends datagrams. package test; import java.lang.Thread; import java.net.*; import java.io.*; public class ChatterClient extends Thread { // Can listen & send on the same socket: private DatagramSocket s; private InetAddress hostAddress; private byte[] buf = new byte[1000]; //设置数据包大小,要比发送的数据大 private DatagramPacket dp = new DatagramPacket(buf, buf.length); // private int id; public ChatterClient(int identifier) { id = identifier; try { // Auto-assign port number: s = new DatagramSocket(0);//参数不填或是0的话 代表随机选择端口发送 s.setSoTimeout(10000);//设置超时时间 hostAddress = InetAddress.getByName("106.13.46.152"); //获得连接端口 } catch(UnknownHostException e) { System.err.println("Cannot find host"); System.exit(1); } catch(SocketException e) { System.err.println("Can't open socket"); e.printStackTrace(); System.exit(1); } System.out.println("ChatterClient starting"); } public void run() { try { for(int i = 0; i < 10; i++) { String outMessage = "Client #" + id + ", message #" + i; // Make and send a datagram: s.send(Dgram.toDatagram(outMessage, hostAddress, ChatterServer.INPORT)); //得到一个DatagramPacket数据包并发送 // Block until it echoes back: s.receive(dp); //接收数据报 // Print out the echoed contents: String rcvd = "Client #" + id + ", rcvd from " + dp.getAddress() + ", " + dp.getPort() + ": " + Dgram.toString(dp); // String rcvd = new String(dp.getData(),0,dp.getLength(),"UTF-8"); System.out.println(dp); } } catch(IOException e) { e.printStackTrace(); System.exit(1); } } public static void main(String[] args) { for(int i = 0; i < 10; i++) new ChatterClient(i).start(); } } ///:~
java 网络编程UDP实例
//: ChatterClient.java
// Tests the ChatterServer by starting multiple
// clients, each of which sends datagrams.
package test;
import java.lang.Thread;
import java.net.*;
import java.io.*;
public class ChatterClient extends Thread {
private final static int PORT = 5000;//要发送的端口
private static final String HOSTNAME = "106.13.46.152";//要连连接的地址
public static void main(String[] args){
try(DatagramSocket socket = new DatagramSocket(0)){//资源自动关闭
socket.setSoTimeout(10000);
InetAddress host = InetAddress.getByName(HOSTNAME);
DatagramPacket request = new DatagramPacket(new byte[1],1,host,PORT);//用于发送的数据报
DatagramPacket response = new DatagramPacket(new byte[1024],1024);//用于接收的数据报
socket.send(request);//发送
socket.receive(response);//接收
String result = new String(response.getData(),0,response.getLength(),"UTF-8");
System.out.println(result);
}catch(IOException e){
e.printStackTrace();
}
}
} ///:~
二.服务器
首先打开一个数据报
DatagramSocket socket = new DatagramSocket(1033) //在内Unix系统上小于1024的端口要root权限
接下来,创建一个接受请求的数据包
Datagrampacket request = new DatagramPacket(new byte[1024],0,1024) ;从0存储到1024
然后接收数据包
socket.receive(request);//这个调用将阻塞,直到接收到数据包
然后再创建一个响应数据包.包括四个部分:要发送的原始数据,待发送的原始数据的字节数,要发送到哪个主机,以及发送到该主机上哪个接口,
java网络编程示例:
package test; import java.io.IOException; import java.net.*; import java.text.DateFormat; import java.text.Format; import java.text.SimpleDateFormat; import java.util.Date; import java.util.Locale; import java.util.logging.*; public class DaytimeUDPServer { private final static int PORT = 1200; private final static Logger audit = Logger.getLogger("requests"); private final static Logger errors = Logger.getLogger("errors"); public static void main(String[] args){ try(DatagramSocket socket = new DatagramSocket(PORT)){ while(true){ try{ System.out.println("start"); DatagramPacket requst = new DatagramPacket(new byte[1024],0,1024); socket.receive(requst); DateFormat df = new SimpleDateFormat(); String daytime = df.format(new Date()).toString(); byte[] data = daytime.getBytes("UTF-8"); DatagramPacket send = new DatagramPacket( data,data.length,requst.getAddress(), requst.getPort()); socket.send(send); audit.info(daytime + " " + requst.getAddress()); }catch(IOException|RuntimeException e){ errors.log(Level.SEVERE,e.getMessage(), e);//发送错误到控制台 } } }catch(IOException e){ errors.log(Level.SEVERE,e.getMessage(),e); } } }
java 编程思想示例
package socket; //: ChatterServer.java //A server that echoes datagrams import java.net.*; import java.io.*; import java.util.*; public class ChatterServer { static final int INPORT = 5000; private byte[] buf = new byte[1000]; private DatagramPacket dp = new DatagramPacket(buf, buf.length); // Can listen & send on the same socket: private DatagramSocket socket; public ChatterServer() { try { socket = new DatagramSocket(INPORT); System.out.println("Server started"); while(true) { // Block until a datagram appears: socket.receive(dp); String rcvd = Dgram.toString(dp) + ", from address: " + dp.getAddress() + ", port: " + dp.getPort(); System.out.println(rcvd); String echoString = "Echoed: " + rcvd; // Extract the address and port from the // received datagram to find out where to // send it back: DatagramPacket echo = Dgram.toDatagram(echoString, dp.getAddress(), dp.getPort()); socket.send(echo); } } catch(SocketException e) { System.err.println("Can't open socket"); System.exit(1); } catch(IOException e) { System.err.println("Communication error"); e.printStackTrace(); } } public static void main(String[] args) { new ChatterServer(); } } ///:~
