rmiimpl.java

SSD8-exam2,这是我的答案

import java.rmi.server.UnicastRemoteObject;
import java.util.Iterator;
import java.util.Vector;
import java.util.Date;
import java.util.HashMap;
import java.text.SimpleDateFormat;

/**
 * Class RMIImpl implenments all the 
 * interface RMIIntf's abstract method. 
 * 
 * @version 1.0   9 June 2007
 * @author 	Zhao Xiaoyu
 */
public class RMIImpl extends UnicastRemoteObject implements RMIIntf{
	
	final static long serialVersionUID = 1564646262L;
	
	/** Define a static hashmap to store username-password pairs */
	private static HashMap<String , String> user = new HashMap<String, String>();
	
	/** Define a static vector to store message items */
	private static Vector<MessageContent> messageList = new Vector<MessageContent>();
	
	/** The variable sdf define time display format of my style */
	private static SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	
	/** Constructor which extends father method default constructor */
	public RMIImpl()throws java.rmi.RemoteException{
		super();
	}
	
	/** Implement the functionality of register users
	 * 
	 *	@para u the u express the usersname 
	 *	@para p the p express the password
	 *	@return return the error message while register-process.  
	 */
	public String register(String u,String p){
		if(!isUserExisted(u)){
			user.put(u, p);
			return "\nRegister Successfully!\n";
		}else 
			return "\nUsername Already Existed, Please select another!\n";
	}
	
	/** Implement the functionality of show users
	 * 
	 *	@return return a list of username or the error message.  
	 */
	public String showusers(){
		
		String returnList = "";
		if(!user.isEmpty()){
			Iterator i = user.keySet().iterator();
			returnList += "\nAll usernames are listing below :\n";
			while(i.hasNext()){
				returnList +=  (String)i.next() + "\n";
			}
			return returnList;
		}else 
			return "\nSorry, There is no user registered now!\n";
		
	}
	
	/** Implement the functionality of check message.
	 * 
	 *	@para u the u express the usersname 
	 *	@para p the p express the password
	 *	@return return the error hint or alist of message.  
	 */
	public String checkmessages(String u, String p){
		int index = 0;
		String returnMessage = "";
		if(isUserExisted(u)){
			if(canLogin(u, p)){
				if(!isUserHasNoMessage(u)){
					Iterator i = messageList.iterator();
					returnMessage +="\nYour messages are listing below :\n";
					
					while(i.hasNext()){
						MessageContent m = (MessageContent)i.next();
						if(m.getReceiver().equals(u)){
							index++;
							returnMessage += "Mail " + index + " :";
							returnMessage += m.toString();
						}
					} 
				}else 
					return "\nSorry, There is no message for you!\n";	
			}else 
				return "\nYour Password Wrong, Input again!\n";
		}else{
			return "\nYou haven't registered yet, Please register first\n";
		}
		return returnMessage;
	}
	
	/** Implement the functionality of leave message.
	 * 
	 *	@para u the u express the usersname 
	 *	@para r the r express the receiver names.
	 *	@para mt the mt express the message content
	 *	@return return the error message.  
	 */
	public String leavemessage(String u, String r, String mt){
		String sendDate = "";
		
		if(isUserExisted(u)){
			if(!u.equals(r)){
				Date now = new Date();
				sendDate = sdf.format(now);
				MessageContent mc = new MessageContent(u, r, sendDate, mt);
				messageList.add( mc ); 
				return "\nLeave message successfully!\n";
			}else 
				return "\nYou shouldn't send message to yourself\n";	
		}else 
			return "\nLogin failed!\n";
	}
	
	/** Implement the functionality of count logic value.
	 * 
	 *	@para u the u express the usersname 
	 *	@return return a boolean to express whether there
	 *	 there is no message for the user.  
	 */
	public boolean isUserHasNoMessage(String u){
		Iterator i = messageList.iterator();
		while(i.hasNext()){
			if(((MessageContent)i.next()).getReceiver().equals(u))
				return false;
		}
		return true;
	}
	
	/** Implement the functionality of count logic value.
	 * 
	 *	@para u the u express the usersname 
	 *	@para p the p express the password
	 *	@return return a boolean to judge whether the user can login.  
	 */
	public boolean canLogin(String u, String p){	
		if(isUserExisted(u)){
			if(user.get(u).equals(p))
				return true;
		}
		return false;
	}
	
	/** Implement the functionality of count logic value.
	 * 
	 *	@para u the u express the usersname 
	 *	@return return a boolean to judge whether the username existed.  
	 */
	public boolean isUserExisted(String u){
		return user.containsKey(u);	
	}
	
}