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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