userlogin.java

一个实现网络会议的软件.包含三个包.其中一个包需JMF的支持.

/*
 * Author: Naizheng Bian
 * Version: 1.0
 * Date: 12/09/2001
 */

package serverPackage;

import java.io.*;
import java.util.*;

import mediaPackage.Constants;
//import mediaPackage.*;
//import serverPackage.*;

/**
 * This class handles the user login 
 */
class UserLogin {
	
	/** The information about the users */
	Hashtable mUserInfoTable = null;
	/** The file output stream to write to a file */
    	FileOutputStream mFileOutStream = null;
    	/** The object output stream for writing to a file */
    	ObjectOutputStream mObjectOutStream = null;
    	/** The variable indicating if the stream is open or not */
    	boolean mOpenStream;
 
	/**
	 * The default Constructor for initialization of the FileInputStream
	 */
	public UserLogin() {
		mUserInfoTable = new Hashtable();
		ObjectInputStream objInStream = null;
        	try {
        		objInStream = new ObjectInputStream(new FileInputStream("userInfo.data"));
        		UserInfo u = (UserInfo) objInStream.readObject();	
    	    		while (u != null) { 
    	    			mUserInfoTable.put(u.getUserName(),u);
    	    			u = (UserInfo) objInStream.readObject();
        		}
    		}catch (EOFException e) {}
    		catch (FileNotFoundException e) {}
        	catch (IOException e) {
            		System.err.println("userLogin:getUserInfo:IOException " + e.getMessage());
        	}
        	catch (Exception e) {
            		System.err.println("userLogin:getUserInfo:Exception " + e.getMessage());
       		}
  		try { if (objInStream != null) objInStream.close(); } 
		catch (IOException ie) {}
        	mOpenStream = false;
	}
	
	/**
	 * This method gets the user password for the given username
	 * If the user is not present in the file then null is returned
	 *
	 * @param userName Name of the user whose password has to be returned
	 * @return The user Information
	 */
	private UserInfo getUserInfo(String userName) {		
		UserInfo info = null;
		info = (UserInfo) mUserInfoTable.get(userName);
    		return info;
        
	}
	
	/**
	 * This method verifies the password of the user and returns true if the user is
	 * allowed to login
	 *
	 * @param userName The user's name 
	 * @param password The user's password 
	 * @return <code>true</code> If the password is correct 
	 *         <code>false</code> If the password is incorrect 
	 */
	public UserInfo loginUser(String userName, String password ,int category) {
  		UserInfo uInfo = getUserInfo(userName);
  		if ((uInfo != null) && ((uInfo.getUserPassword()).equals(password))&&(category==Constants.USER||category==uInfo.getCategory())) {
  			return uInfo;
        	}
        	return null;        
    	}
    
    /**
     * This method adds a new user
     * @param uInfo The information about the new user
     * @return true, if the new information is added, otherwise returns false
     */
    private boolean addUser(UserInfo uInfo) {
    	Object o = mUserInfoTable.put(uInfo.getUserName(),uInfo);
    	if (o != null) return false;
        if (!mOpenStream) {
	        try {
	                mFileOutStream = new FileOutputStream("userInfo.data");
	                mObjectOutStream = new ObjectOutputStream(mFileOutStream);
	                Enumeration e = mUserInfoTable.elements();
	                while (e.hasMoreElements()) {
	                	UserInfo usInfo = (UserInfo) e.nextElement();
	                	mObjectOutStream.writeObject(usInfo);
	                }
	        }
	        catch (IOException e) {
	                System.err.println("userLogin:addUser:IOException " + e.getMessage());
	        }
	        catch (Exception e) {
	                System.err.println("userLogin:addUser:Exception " + e.getMessage());
	        }
	        mOpenStream = true;
        }
    	try {
   			mObjectOutStream.writeObject(uInfo);
   			mObjectOutStream.flush();
    	}
    	catch (IOException e) {
    		System.err.println("userLogin:addUser:IOException " + e.getMessage());
    		return false;
    	}
    	catch (Exception e) {
    		System.err.println("userLogin:addUser:Exception " + e.getMessage());
    		return false;
    	}

    	return true;
    }
    
	/**
	 * This method registers a new user and returns true if the user is
	 * registered successfully
	 *
	 * @param userName The name of the user
	 * @param password The password of the user
	 * @return true If the user is registered succcessfully
	 *         false If the user cannot be registered
	 */    
    public boolean registerUser(UserInfo usInfo) {
    	
    	UserInfo uInfo = getUserInfo(usInfo.getUserName());
    	if (uInfo != null) {
    		return false;
    	}
    	return addUser(usInfo);
    	
    }
    
}