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用Java语言实现数据报编程之单播讲解

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本文章讲述了用Java语言实现数据报编程之单播讲解.

 实

际上,单播就是一个报文从源主机向另一个目标主机发送,接收目标只有一个。

首先,写收发器类DatagramRecvSender_s,这个类既要发送数据报又要接收数据报,发送一个文件夹中的所有图片,一张一张的进行,接收是在一个线程中进行,每收完一个文件,就激活一个事件,事件处理器处理这个事件。

类清单为:

package recmail.multiservice;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.SocketException;

import java.net.SocketAddress;

import java.net.UnknownHostException;

import java.net.InetSocketAddress;

import java.io.IOException;

import java.util.ArrayList;

import java.net.InetAddress;

import java.io.File;

import java.util.Iterator;

public class DatagramRecvSender_s extends DataSwapListenerAdapter

implements Runnable {

public static final int DatagramPort = 10698;

private java.net.DatagramSocket road;

private InetAddress ia;

DatagramPacket dp;

public static final int Datagram_Length = 8192;

private DataPacket cdp;

private boolean ishandling = true;

DataSwapEvent dsevent;

/**

* 这个构造器用于接收数据报.

*/

public DatagramRecvSender_s() {

try {

System.out.println("recv ...");

ia = InetAddress.getByName("localhost");//192.168.0.17"127.0.0.1"

dsevent = new DataSwapEvent(this);

SocketAddress sa = new InetSocketAddress(ia,

DatagramRecvSender_s.DatagramPort);

//至少要指定数据报接收端口,这是对接收端的唯一要求.当然如果主机是多址主机,需要road = new DatagramSocket(sa);

road = new DatagramSocket(DatagramRecvSender_s.DatagramPort);

System.out.println(road.isBound()+"::"+road.getBroadcast());

}

catch (SocketException ex) {

ex.printStackTrace();

}

catch (Exception ex1) {

ex1.printStackTrace();

}

}

/**

* 这个构造器用于发送数据报.

* @param send String

*/

public DatagramRecvSender_s(String send) {

try {

System.out.println("start sending ...");

ia = InetAddress.getByName("192.168.0.4");//"255.255.255.255""192.168.0.4""127.0.0.1"

dsevent = new DataSwapEvent(this);

SocketAddress sa = new InetSocketAddress(ia,

DatagramRecvSender_s.DatagramPort);

//如果需要接收数据报,就需要指定一个端口,否则不必指定.road = new DatagramSocket(DatagramRecvSender_s.DatagramPort-1);

road = new DatagramSocket();

System.out.println("isBound--"+road.isBound()+":getBroadcast--"+road.getBroadcast());

}

catch (SocketException ex) {

ex.printStackTrace();

}

catch (UnknownHostException ex1) {

ex1.printStackTrace();

}

}

public void sendFile(String file) {

cdp = new DataPacket(file);

System.out.println(file);

Iterator it = cdp.getDataPackets().iterator();

byte[] b;

while (it.hasNext()) {

b = ( (DataEntry) it.next()).getByte();

//数据报是自包含的,自描述的数据,它的投递是由路由器执行的,路由器路由算法根据报文的目标地址选择适当的路由递送报文,

//所以数据报中要指定目标IP地址和目标主机处理端口.

DatagramPacket dp = new DatagramPacket(b, 0, b.length, ia,DatagramRecvSender_s.DatagramPort);

try {

Thread.sleep(100);

if(dp==null)

continue;

road.send(dp);

}

catch (Exception ex) {

ex.printStackTrace();

}

}

}

public boolean isHandling() {

return ishandling;

}

public void isHandling(boolean ishand) {

ishandling = ishand;

}

public void run() {

byte[] buffer = new byte[DataPacket.DataSwapSize];

DatagramPacket packet = new DatagramPacket(buffer, buffer.length);

DataPacket dp = new DataPacket();

while (ishandling) {

packet.setLength(buffer.length);

System.out.println("wait .. ");

try {

road.receive(packet);

dp.Add(packet.getData());

if (dp.isFull()) {

dsevent.setImage(dp.Gereratedata());

this.processRecvFinishedEvent(dsevent);

dp = new DataPacket();

}

}

catch (IOException ex) {

System.out.println(ex);

}

}

}

public static void main(String[] args) {

String file[];

ArrayList al = new ArrayList();

String path = "E:\nature\";

File f = new File(path);

file = f.list();

DatagramRecvSender_s dgrs = new DatagramRecvSender_s("");

for(int j=0;j<1000;j++)

for (int i = 0; i < file.length; i++) {

try {

Thread.sleep(2000);

}

catch (InterruptedException ex) {

}

if (file[i].endsWith("jpg") || file[i].endsWith("bmp"))

dgrs.sendFile(path + file[i]);

}

}

}

下面看接收端的界面.

package recmail.multiservice;

import java.awt.BorderLayout;

public class testDual

extends DualWindow implements DataSwapListener {

JImagePanel ip;

java.awt.Image bi;

public testDual() {}

public void init() {

super.init();

ImageShow is = new ImageShow();

is.addDataSwapListener(this);

Thread thread = new Thread(is, "test");

thread.start();

}

public static void main(String[] args) {

testDual test = new testDual();

test.initmain();

test.go();

DatagramRecvSender_s dgrs = new DatagramRecvSender_s();

dgrs.addDataSwapListener(test);

Thread thread = new Thread(dgrs, "test");

thread.start();

}

public void initmain() {

super.initmain();

ip = new JImagePanel();

root.setLayout(new BorderLayout(5, 5));

root.add(ip, BorderLayout.CENTER);

}

public void OnDataSendFinished(Object s, DataSwapEvent e) {}

public void OnDataRecvFinished(Object s, DataSwapEvent e) {

this.bi = e.getImage();

ip.setImage(bi);

System.out.println("recv Finished!");

}

}

testDual扩展的DualWindow类清单:

package recmail.multiservice;

import javax.swing.JPanel;

import javax.swing.JFrame;

import javax.swing.JApplet;

public class DualWindow

extends JApplet {

protected JPanel root;

private JFrame frame;

public DualWindow() {}

public void init() {

root = new JPanel();

this.setContentPane(root);

}

public void initmain() {

root = new JPanel();

}

public static void main(String[] args) {

testDual test = new testDual();

test.initmain();

test.start();

test.go();

}

public void go() {

frame = new JFrame();

frame.setContentPane(root);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

frame.setSize(300, 200);

frame.validate();

frame.setVisible(true);

}

}

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