一些学习java的练习作业 新手向参考资料 第6部分

				// 儅儖僠僉儍僗僩斉僠儍僢僩僾儘僌儔儉Chat.java
				// 偙偺僾儘僌儔儉偼,儅儖僠僉儍僗僩傪巊偭偰僠儍僢僩婡擻傪採嫙偟傑偡
				// 巊偄曽java Chat [億乕僩斣崋]
				
				// 儔僀僽儔儕偺棙梡
				import java.net.*;
				import java.io.*;
				
				// Chat僋儔僗
				// Chat僋儔僗偼,庴怣僗儗僢僪傪嶌惉丒幚峴偟,憲怣傪扴摉偟傑偡
				public class Chat {
					final byte TTL = 1 ;//摨堦僙僌儊儞僩撪晹偺傒摓払壜擻偲偟傑偡
					final String MULTICASTADDRESS = ("224.0.0.1") ;
								// 儅儖僠僉儍僗僩傾僪儗僗224.0.0.1偼,
								// 儖乕僞傪挻偊側偄応崌偺傾僪儗僗偱偡
					int port = 6000 ;
								// 僠儍僢僩梡偺億乕僩斣崋,巜掕偑側偗傟偽6000 斣偲偟傑偡
					byte[] buff = new byte[1024] ;//憲怣梡僶僢僼傽
					String myname ="" ;// 棙梡幰柤
					int nameLength = 0 ;//棙梡幰柤偺挿偝
					MulticastSocket soc = null ; // 儅儖僠僉儍僗僩僜働僢僩
					InetAddress chatgroup = null ; //僠儍僢僩梡傾僪儗僗
				
					// 僐儞僗僩儔僋僞棙梡幰柤側偳傪愝掕偟傑偡
					public Chat(int portno){
					port = portno ; //億乕僩斣崋偺愝掕
					BufferedReader lineread
					  = new BufferedReader(new InputStreamReader(System.in)) ;
					System.out.println("偍柤慜傪偳偆偧") ;
					try{
						myname = lineread.readLine() ;
					}catch(Exception e){
						e.printStackTrace() ;
						System.exit(1) ;
					}
					System.out.println("傛偆偙偦" + myname + "偝傫.") ;
					myname = myname + ">" ;
					nameLength = (myname.getBytes()).length ;
					for(int i = 0;i < nameLength;++i)
						buff[i] = (myname.getBytes())[i] ;
					}
				
					// makeMulticastSocket儊僜僢僪
					//MULTICASTADDRESS偵懳偟偰儅儖僠僉儍僗僩僜働僢僩傪嶌惉偟傑偡
					public void makeMulticastSocket()
					{
						try{
							chatgroup
								= InetAddress.getByName(MULTICASTADDRESS) ;
							soc = new MulticastSocket(port) ;
							soc.joinGroup(chatgroup) ;
						}
						catch(Exception e){
							e.printStackTrace() ;
							System.exit(1);
						}
					}
				
					// startLintener儊僜僢僪
					// 僗儗僢僪梡僋儔僗ListenPacket偺僆僽僕僃僋僩傪惗惉偟,婲摦偟傑偡
					public void startListener()
					{
						try{
							ListenPacket lisner =
								new ListenPacket(soc);
							Thread lisner_thread = new Thread(lisner);
							lisner_thread.start();//庴怣僗儗僢僪偺奐巒
						}
						catch(Exception e){
							e.printStackTrace() ;
							System.exit(1);
						}
					}
				
					// sendMsgs儊僜僢僪
					// 儅儖僠僉儍僗僩僷働僢僩偺憲怣傪扴摉偟傑偡
					public void sendMsgs()
					{
						try{
							// 憲怣儖乕僾
							while(true){
								int n = System.in.read(
										buff,nameLength ,1024 - nameLength ) ;
								if(n > 0){
									DatagramPacket dp
										= new DatagramPacket(
										buff,n + nameLength,chatgroup,port) ;
									soc.send(dp) ;
								}
								else break ;// 儖乕僾廔椆
							}
						}
						catch(Exception e){
							e.printStackTrace() ;
							System.exit(1);
						}
					}
				
					// quitGroup儊僜僢僪
					// 愙懕傪廔椆偟傑偡
					public void quitGroup()
					{
						try{
							// 愙懕偺廔椆
							System.out.println("愙懕廔椆") ;
							soc.leaveGroup(chatgroup) ;
							System.exit(0) ;
						}
						catch(Exception e){
							e.printStackTrace() ;
							System.exit(1);
						}
					}
				
					// main儊僜僢僪
					public static void main(String[] arg){
						Chat c = null ;
						int portno = 6000 ;
						if(arg.length >= 1) portno = Integer.parseInt(arg[0]) ;
						c = new Chat(portno) ;
						c.makeMulticastSocket() ;
						c.startListener() ;
						c.sendMsgs() ;
						c.quitGroup() ;
					}
				}
				
				// ListenPacket僋儔僗
				// 儅儖僠僉儍僗僩僷働僢僩傪庴怣偟傑偡
				class ListenPacket implements Runnable {
					MulticastSocket s = null;
					// 僐儞僗僩儔僋僞儅儖僠僉儍僗僩僗儗僢僪傪庴偗庢傝傑偡
					public ListenPacket(MulticastSocket soc){
						s = soc;
					}
					// 張棟偺杮懱
					public void run(){
						byte[] buff = new byte[1024] ;
						try{
							while(true){
								DatagramPacket recv
									= new DatagramPacket(buff,buff.length) ;
								s.receive(recv) ;
								if(recv.getLength() > 0){
									System.out.write(buff,0,recv.getLength()) ;
								}
							}
						}catch(Exception e){
							e.printStackTrace() ;
							System.exit(1) ;
						}
					}
				}