实验七 组播编程
实验七 组播编程
实验目的：
1、理解基于组播编程的基本原理；
2、学会组播编程实例的代码编写及理解各语句内容；
3、掌握MulticastSocket类的相关知识；
4、掌握基于组播编程的具体应用。
实验要求：
1、建立两个独立的基于组播编程的JAVA工程，用于服务器和客户端系统；
2、在工程中建立相关的JAVA类，拷贝代码后调试运行，使其能正确运行且能实现组播通信；
3、对组播程序的功能进行拓广，使用于某一具体的应用。
实验内容：
1、建立服务器端工程和三个JAVA类，类程序的原代码为：
//******************************************************************************************************//
public class ServerTest {
public static void main(String[] args) throws java.io.IOException {
new SonServerThreadTest().start();
}
}
//******************************************************************************************************//
import java.io.*;
import java.net.*;
import java.util.*;
class ServerThread
extends Thread {
protected DatagramSocket socket = null;
protected BufferedReader in = null;
protected boolean moreQuotes = true;
public ServerThread() throws IOException {
this("ServerThread");
}
public ServerThread(String name) throws IOException {
super(name);
socket = new DatagramSocket(4445);
try {
in = new BufferedReader(new FileReader("one-liners.txt"));
}
catch (FileNotFoundException e) {
System.err.println("Could not open quote file. Serving time instead.");
}
}
public void run() {
while (moreQuotes) {
try {
byte[] buf = new byte[256];
// receive request
DatagramPacket packet = new DatagramPacket(buf, buf.length);
socket.receive(packet);
// figure out response
String dString = null;
if (in == null) {
dString = new Date().toString();
}
else {
dString = getNextQuote();
}
buf = dString.getBytes();
// send the response to the client at "address" and "port"
InetAddress address = packet.getAddress();
int port = packet.getPort();
packet = new DatagramPacket(buf, buf.length, address, port);
socket.send(packet);
}
catch (IOException e) {
e.printStackTrace();
moreQuotes = false;
}
}
socket.close();
}
protected String getNextQuote() {
String returnValue = null;
try {
if ( (returnValue = in.readLine()) == null) {
in.close();
moreQuotes = false;
returnValue = "No more quotes. Goodbye.";
}
}
catch (IOException e) {
returnValue = "IOException occurred in server.";
}
return returnValue;
}
}
//******************************************************************************************************//
import java.io.*;
import java.net.*;
import java.util.*;
class SonServerThreadTest
extends ServerThread {
private long FIVE_SECONDS = 5000;
public SonServerThreadTest() throws IOException {
super("SonServerThreadTest");
}
public void run() {
while (moreQuotes) {
try {
byte[] buf = new byte[256];
// construct quote
String dString = null;
if (in == null) {
dString = new Date().toString();
}
else {
dString = getNextQuote();
}
buf = dString.getBytes();
// send it
InetAddress group = InetAddress.getByName("10.189.0.88");
DatagramPacket packet = new DatagramPacket(buf, buf.length, group,
4446);
socket.send(packet);
// sleep for a while
try {
sleep( (long) (Math.random() * FIVE_SECONDS));
}
catch (InterruptedException e) {}
}
catch (IOException e) {
e.printStackTrace();
moreQuotes = false;
}
}
socket.close();
}
}
//******************************************************************************************************//
2、建立客户端工程和JAVA类，类程序的原代码为：
import java.io.*;
import java.net.*;
public class ClientTest {
public static void main(String[] args) throws IOException {
MulticastSocket socket = new MulticastSocket(4446);
InetAddress address = InetAddress.getByName("10.189.0.88");
socket.joinGroup(address);
DatagramPacket packet;
for (int i = 0; i < 5; i++) {
byte[] buf = new byte[256];
packet = new DatagramPacket(buf, buf.length);
socket.receive(packet);
String received = new String(packet.getData());
System.out.println("Quote of the Moment: " + received);
}
socket.leaveGroup(address);
socket.close();
}
}
3、调试使以上两个工程能正常运行，使服务端和客户端能正常通信（注意：运行时可以先运行多个客户端，再运行服务器端）。
4、对服务器端和客户端的程序代码进行阅读和理解，要求做到每条语句都能明白其具体含义，每个类都了解其功能。
5、对以上程序进行适当的修改，要求数据报通信功能保持实现。
（修改的方向有：组播窃听器、组内通告等。）
6、撰写实验报告
实验报告包含：实验报告首页、实验步骤（每步的内容，有程序的要求有源码和运行结果及结果描述）、实验心得。