multicastserver2.java

Java案例开发集锦,里面提供了很好的学习例子

/**
 * @author wangmj
 *可以通过这个方法将服务器收到的信息广播给大家。
 * 首先 java MulticastServer2
 * 然后 java MulticastClient
 * 服务器最终会把从文件中读出的信息广播给大家。
 * MulticastServer2.java
 */
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Date;
public class MulticastServer2 {
        public static void main(String[] args) throws java.io.IOException{
                new MulticastServerThread().start();
        }
}
class MulticastServerThread extends QuoteServerThread2{
        private long FIVE_SECONDS = 5000;
        //public MulticastServerThread
        public MulticastServerThread() throws IOException{
                super("MulticastServerThread");
        }
        boolean moreQuotes = true;
        String dString = null;
        public void run(){
                while(moreQuotes){
                        try{
                                byte[] buf = new byte[256];
                                //construct quote 引用, 引证, 提供, 提出, 报(价)
                                Date date = null;
                                date = new Date();
                                if(dString == null){
                                        dString = new String(date.toString());
                                } else {
                                        dString = getNextQuote();
                                }
                                buf = dString.getBytes();

                                //send it
                                InetAddress group = null;
                                try {
                                        group = InetAddress.getByName("230.0.0.1");
                                } catch (UnknownHostException e) {
                                        e.printStackTrace();
                                }
                                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){
                                        e.getMessage();
                                }
                        }catch(IOException e){
                                e.printStackTrace();
                                moreQuotes = false;
                        }
                }
                socket.close();
        }
}
class QuoteServerThread2 extends Thread{
        protected DatagramSocket socket = null;
        protected BufferedReader in = null;
        protected boolean moreQuotes = true;
        public QuoteServerThread2() throws IOException{
                this("QuoteServerThread");
        }
        public QuoteServerThread2(String name) throws IOException{
                super(name);
                socket = new DatagramSocket(4446);
                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 reques
                                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 "potr"
                                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 value = null;
                try{
                        if((value = in.readLine())==null){
                                in.close();
                                moreQuotes = false;
                                value="No more quotes.Goodbye.";
                        }
                }catch(IOException e){
                        value = "IOException occurred in server";
                }finally{
                        System.out.println("getNextQuote "+value);
                }
                return value;
        }
}