有了以上三個javabean，只是==有了三個數據表（事實上，如果要保存聊天信息在數據庫中，建立表進行插入刪除更新即可），還要有掌控全局的ChatroomManager類。下面先給出完整代碼。
package org.jvk.chatroom.service;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.commons.digester.Digester;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jvk.chatroom.bean.Message;
import org.jvk.chatroom.bean.Room;
import org.jvk.chatroom.bean.User;
import org.xml.sax.SAXException;
publicclass ChatroomManager {
private static Log log = LogFactory.getLog(ChatroomManager.class);
private ChatroomManager() {
}
private static ChatroomManager instance = new ChatroomManager();
private Map<String, Room> rooms = new HashMap<String, Room>();
public static ChatroomManager newInstance() {
return instance;
}
public synchronized void config(FileInputStream in) throws IOException, SAXException{
log.info("初始化聊天室配置信息");
Digester digester = new Digester();
digester.setValidating(false);
digester.push(this);
digester.addObjectCreate("rooms/room", Room.class);
digester.addBeanPropertySetter("rooms/room/name", "name");
digester.addBeanPropertySetter("rooms/room/notice", "notice");
digester.addBeanPropertySetter("rooms/room/maxMessage", "maxMessage");
digester.addBeanPropertySetter("rooms/room/maxUser", "maxUser");
digester.addSetNext("rooms/room", "addRoom");
digester.parse(in);
log.info("聊天室配置信息初始化完畢");
}
public synchronized void config(File file) throws IOException{
log.info("聊天室配置文件:"+file.getAbsolutePath());
config(new FileInputStream(file));
}
public Map<String, Room> getRooms() {
return rooms;
}
public void setRooms(Map<String, Room> rooms) {
this.rooms = rooms;
}
public Room getRoom(String roomName) {
return rooms.get(roomName);
}
public Room getRoom(User user) {
return user.getRoom();
}
public void addRoom(Room room) {
rooms.put(room.getName(), room);
}
public void addUserToRoom(User user) {
rooms.get(user.getRoom().getName()).addUser(user);
}
public void removeUserFromRoom(User user) {
rooms.get(user.getRoom().getName()).removeUser(user);
}
public void addMessageToRoom(Message message, Room room) {
rooms.get(room.getName()).addMessage(message);
}
public List<Message> getMessagesFromRoom(User user) {
return user.getRoom().getMessages(user);
}
public List<User> getUsersFromRoom(User user) {
return getRoom(user).getUsers(user);
}
public boolean exists(String roomName, String userName) {
Room room = getRoom(roomName);
for (User user : room.getUsers())
if (user.getName().equalsIgnoreCase(userName))
returnt rue;
return false;
}
public boolean exists(Room room, String userName) {
for (User user : room.getUsers())
if (user.getName().equalsIgnoreCase(userName))
return true;
return false;
}
}
其中 config(FileInputStream in) 方法通過讀取配置文件初始化聊天室。配置文件是一個XML格式文件，解析XML文件時使用了commons-digester 包的Digester。Digester可以讓我們輕易地把XML轉換爲Java對象。（詳情請訪問http://commons.apache.org/digester/）。
從以下的java代碼
digester.addObjectCreate("rooms/room", Room.class);
digester.addBeanPropertySetter("rooms/room/name", "name");
digester.addBeanPropertySetter("rooms/room/notice", "notice");
digester.addBeanPropertySetter("rooms/room/maxMessage", "maxMessage");
digester.addBeanPropertySetter("rooms/room/maxUser", "maxUser");
digester.addSetNext("rooms/room", "addRoom");
可以猜到XML配置文件是這樣的：
<?xml version="1.0" encoding="GBK"?>
<rooms>
<room>
<name>我的聊天室</name>
<notice>歡迎交流學習</notice>
<maxMessage>10</maxMessage>
<maxUser>100</maxUser>
</room>
<room>
<name>你的聊天室</name>
<notice>歡迎交流娛樂</notice>
<maxMessage>15</maxMessage>
<maxUser>150</maxUser>
</room>
</rooms>
這個類除了讀取配置文件進行初始化外，還擔當“門面模式”的角色，以後不管如何操作Message、User和Room三個類，都通過ChatroomManager間接進行。
因爲Room對象包含了User和Message，所以這裏只需要一個Room的集合：
private Map<String, Room> rooms = new HashMap<String, Room>();
只要有Room在手，一切掌握之中。
接下來可以進行 Servlet 的編寫了。