ajax入门是初学者的宝典

package lee; import java.util.*; import java.io.*; /* * @author yeeku.H.lee kongyeeku@163.com * @version 1.0 * <br>Copyright (C), 2005-2008, yeeku.H.Lee * <br>This program is protected by copyright laws. * <br>Program Name: * <br>Date: */ public class ChatService { private static ChatService cs; private Properties userList; private LinkedList<String> chatMsg; private ChatService() { } public static ChatService instance() { if (cs == null) { cs = new ChatService(); } return cs; } public boolean validLogin(String user , String pass) throws IOException { if (loadUser().getProperty(user) == null) { return false; } if (loadUser().getProperty(user).equals(pass)) { return true; } return false; } public boolean addUser(String name , String pass) throws Exception { if (userList == null) { userList = loadUser(); } if (userList.containsKey(name)) { throw new Exception("用户名已经存在，请重新选择用户名"); } userList.setProperty(name , pass); saveUserList(); return true; } public String getMsg() { if (chatMsg == null) { chatMsg = new LinkedList<String>(); return ""; } String result = ""; for (String tmp : chatMsg) { result += tmp + "\n"; } return result; } public void addMsg(String user , String msg) { if (chatMsg == null) { chatMsg = new LinkedList<String>(); } if (chatMsg.size() > 40) { chatMsg.removeFirst(); } chatMsg .add(user + "说：" + msg); } ////////////////////////////////////////////////////////////// // 下面是系统的工具方法 ///////////////////////////////////////////////////////////// private Properties loadUser()throws IOException { if (userList == null) { File f = new File("userFile.properties"); if (!f.exists()) f.createNewFile() ; userList = new Properties(); userList.load(new FileInputStream(f)); } return userList; } private boolean saveUserList()throws IOException { if (userList == null) { return false; } userList.store(new FileOutputStream("userFile.properties"), "userList"); return true; } }