简单的双向消息发送的聊天程序

一个用rmi实现简单的双向消息发送的聊天程序，客户机可以向服务器注册自己.
此代码原自developing　java　enterprise　app一书（自己写不了，），本机调试通过．

一：远程接口
接口１：
package message;
import java.rmi.Remote;
import java.rmi.RemoteException;
/**
 * coder: taie
 */
public interface MessageReceiver extends Remote{
    void print(String s) throws RemoteException;
}

接口２：
package message;
import java.rmi.Remote;
import java.rmi.RemoteException;
/**
 * coder: taie
 */
public interface MessageServer extends Remote {
    static String SERVER_NAME = "Message_Server";
    static int FAILURE=-1;
    static int success=0;
    void send(String name, String message) throws RemoteException;
    int register(String name,MessageReceiver m)throws RemoteException;
}
javac 编译以上接口．

二：服务器端，server类
package server;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.UnicastRemoteObject;
import java.util.Enumeration;
import java.util.Hashtable;

import message.MessageReceiver;
import message.MessageServer;
/**
 * coder: taie
 */
public class Server extends UnicastRemoteObject implements MessageServer{
    // a hashtable    存储用户
    static Hashtable receivers=new Hashtable(5);
    public Server()throws RemoteException{
        super();
    }
    public void send(String name,String message)throws RemoteException{
        for(Enumeration e=receivers.elements();e.hasMoreElements();)
        {MessageReceiver m=(MessageReceiver)e.nextElement();
            m.print(name+":"+message);
        }
    }
   
    public int register(String name,MessageReceiver m){
        int retval=MessageServer.FAILURE;
        // 空注册检测
        if((name!=null)&&(m!=null)){
           //唯一用户名 
            if(receivers.get(name)==null)
            {
                receivers.put(name,m);
                System.out.println("added "+name);
                retval=MessageServer.success;
            }else{
                System.out.println("Could not add client because"+name
                        +"already exists on server.");
            }
        }
        return retval;
    }
    public static void main(String[] args){
       // System.setSecurityManager(new RMISecurityManager());
        try{
            //create an instance 
            MessageServer srv=new Server();
           
            //server类创建注册表
              Registry reg=LocateRegistry.createRegistry(
              Registry.REGISTRY_PORT);
             reg.rebind(MessageServer.SERVER_NAME,srv);
              System.out.println("Server bound and Started!");
        }catch(Exception e){
            System.err.println("Server exception:"+e.getMessage());
            e.printStackTrace();
            }
    }
}
rmic　server.Server
server类创建了自己的注册表，不需要运行rmiregistry
三：客户端，client，主要是界面编码
package client;
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.TextArea;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.rmi.Naming;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import message.MessageReceiver;
import message.MessageServer;
/**
 * coder: taie
 */
public class Client extends Frame implements MessageReceiver,
      ActionListener{
    TextField tf;
    TextArea ta;
    static String name;
    static MessageServer server;
    public Client()throws RemoteException{
        setTitle(name);
        setLayout(new BorderLayout());
        tf=new TextField(30);
        tf.addActionListener(this);
        add("South",tf);
        ta=new TextArea(20,20);
        add("Center",ta);
        addWindowListener(new WindowCloser());
        UnicastRemoteObject.exportObject(this);
    }
    public void actionPerformed(ActionEvent e){
        try{
            server.send(name,tf.getText());
        }catch(Exception ea){
            System.out.println("Client exception "+ea.getMessage());
            ea.printStackTrace();
        }
        tf.setText("");
        tf.selectAll();
    }
    public void print(String s){
        ta.append(s+"\n");
    }
    public static void main(String[] args){
        if(args.length<1){
            System.out.println("usage:java client.client ClientName.");
            System.exit(-1);
        }
        name=args[0];
        try{
            Client cf=new Client();
            cf.pack();
            cf.show();
            server=(MessageServer)Naming.lookup(
                    MessageServer.SERVER_NAME);
            int s=server.register(args[0],cf);
            if(s==MessageServer.FAILURE)throw new Exception(
                    "could not connect to server.");
        }catch(Exception e){
            System.err.println("Client exception: "+e.getMessage());
            e.printStackTrace();
            System.exit(-1);
        }
    }
   
}

class WindowCloser extends WindowAdapter{
    public void windowClosing(WindowEvent e){
        System.exit(-1);
    }   
}
rmic client.Client 编译客户端

各项编译通过后，首先java　server.Server启动服务器端，
再执行客户端（５个以内，这里开启２个）java client.Client test1；java client.Client test2
2个客户端正常通信，本机调试通过．

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