一个使用数据报通讯方式的聊天程序实例,含客户端和后台.doc

/*客户端：ChatClient.java*/import .*;import java.io.*;ublic class ChatClient private DatagramSocket s; private InetAddress hostAddress; private byte buf = new byte1000; private DatagramPacket dp = new DatagramPacket(buf,buf.length);/* *方法说明：构造器，这里实现接收用户输入和与服务器通讯 *输入参数： *返回类型： */ public ChatClient() try /使用构造器，创建使用本机任何可用端口的数据包Socket s = new DatagramSocket(); /获取本地IP hostAddress = InetAddress.getByName(localhost); System.out.println(Client start.); while(true) String outMessage =; /读取输入 BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in); try outMessage = stdin.readLine(); catch(IOException ie) System.err.println(IO error!); /如果输入“bye”则表示退出程序 if(outMessage.equals(bye) break; String outString = Client say: + outMessage; byte buf = outString.getBytes(); /打包数据，发送数据 DatagramPacket out = new DatagramPacket(buf,buf.length,hostAddress,ChatServer.PORT); s.send(out); /等待服务器返回 s.receive(dp); String rcvd = rcvd from + dp.getAddress() + , + dp.getPort() + : + new String(dp.getData(),0,dp.getLength(); System.out.println(rcvd); catch(UnknownHostException e) System.out.println(Can;t open socket); System.exit(1); catch(SocketException e) System.out.println(Can;t open socket); e.printStackTrace(); System.exit(1); catch(IOException e) System.err.println(Communication error); e.printStackTrace(); System.exit(1); catch(Exception e) System.err.println(Communication error); e.printStackTrace(); System.exit(1); System.out.println(ChatClient over); /* *方法说明：主方法 *输入参数： *返回类型： */ public static void main(String args) new ChatClient(); /*服务器端：ChatClient.java*/import .*;import java.io.*;import java.util.*;public class ChatServer static final int PORT = 4000;/设置服务端口 private byte buf = new byte1000; private DatagramPacket dgp =new DatagramPacket(buf,buf.length); private DatagramSocket sk;/* *方法说明：服务端构造器，实现读取用户输入和通讯 *输入参数： *返回类型： */ public ChatServer() try /实例化数据报 sk = new DatagramSocket(PORT); System.out.println(Server start.); while(true) /等待接收 sk.receive(dgp); /获取接收信息 String rcvd = new String(dgp.getData(),0,dgp.getLength()+ , from address: + dgp.getAddress()+ , port: + dgp.getPort(); System.out.println(rcvd); String outMessage =; /读取输入 BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in); try outMessage = stdin.readLine(); catch(IOException ie) System.err.println(IO error!); String outString = Server say: + outMessage; /拷贝字符到缓存 byte buf = outString.getBytes(); /打包数据，发送回信息。 DatagramPacket out = new DatagramPacket(buf,buf.length,dgp.getAddress(),dgp.getPort(); sk.send(out); catch(SocketException e) System.err.println(Cant open socket); System.exit(1); catch(IOExceptio