实现了隐形耦合，help输出内容与help的输出函数无关，使得新的命令加入的时候，help能自动输出新的内容。
添加了新元素：添加了简单的故事场景。
城堡游戏演示：

代码如下：

Game.java

城堡游戏的主函数

package castle;import java.util.ArrayList;
import java.util.HashMap;
import java.util.Scanner;public class Game {private Room currentRoom;private HashMap<String, Handler> handlers = new HashMap<String, Handler>();protected ArrayList<String> cmds = new ArrayList<String>();public Game() {
//    	handlers.put("go", new HandlerGo());handlers.put("bye", new HandlerBye(this));handlers.put("help", new HandlerHelp(this));handlers.put("go", new HandlerGo(this));for (String cmd : handlers.keySet()) {cmds.add(cmd);}createRooms();}private void createRooms(){Room outside, lobby, pub, study, bedroom, inside, bedroomup;//	制造房间outside = new Room("城堡外");inside = new Room("城堡内");lobby = new Room("大堂");pub = new Room("小酒吧");study = new Room("书房");bedroom = new Room("卧室");bedroomup = new Room("卧室二楼");
//        hoteldown = new Room("宾馆一楼");
//        hotelup = new Room("宾馆二楼");// 设置房间故事outside.setNarration("城堡外","恭喜你逃出了城堡");inside.setNarration("城堡内", "你现在在城堡的一个恐怖黑暗的广场上");lobby.setNarration("大堂", "你来到了城堡的大堂，大堂里面有着恐怖的石像");pub.setNarration("小酒吧", "这是一间幽深的酒吧，傍边到处是黑色的酒瓶，还有这恐怖的音乐在播放着");study.setNarration("书房", "这是城堡的书房，里面记载着这个城堡的过去");bedroom.setNarration("卧室", "你来到了城堡主人的卧室，这里是最黑暗的地方，你的心跳跳的越来越快，快点离开这里吧！");bedroomup.setNarration("卧室二楼", "恭喜你来到了城堡主人的卧室二楼，并且发现了一个箱子，你打开箱子后找到了钥匙，请拿着钥匙快速逃出城堡吧！");//	初始化房间的出口outside.setExit("south", inside);inside.setExit("north", outside);inside.setExit("east", lobby);inside.setExit("south", study);inside.setExit("west", pub); lobby.setExit("west", inside);pub.setExit("east", inside);study.setExit("north", inside);study.setExit("east", bedroom);bedroom.setExit("west", study);bedroom.setExit("up", bedroomup);bedroomup.setExit("down", bedroom);currentRoom = inside;  //	从城堡门外开始}private void printWelcome() {System.out.println();System.out.println("欢迎来到城堡！");System.out.println("这是一个超级无聊的游戏。任务：你需要在城堡内找到宝箱钥匙并带到城堡外去。");System.out.println("如果需要帮助，请输入 'help' 。");System.out.println();showPrompt();}// 以下为用户命令public void goRoom(String direction) {Room nextRoom = currentRoom.getExit(direction);if (nextRoom == null) {System.out.println("那里没有门！");}else {currentRoom = nextRoom;showPrompt();}}public void showPrompt() {String currentnarration = currentRoom.getNarration(currentRoom.toString());System.out.println("你在" + currentRoom + "\n场景描述：" + currentnarration);System.out.print("出口有: ");System.out.print(currentRoom.getExitDesc());System.out.println();}public void play() {Scanner in = new Scanner(System.in);while ( true ) {String line = in.nextLine();String[] words = line.split(" ");Handler handler = handlers.get(words[0]);String value = "";if ( words.length > 1)value = words[1];if ( handler != null) {handler.doCmd(value);if ( handler.isBye()) {break;}}}in.close();}public static void main(String[] args) {Game game = new Game();game.printWelcome();game.play();System.out.println("感谢您的光临。再见！");}}

Room.java

城堡游戏中的房间模块

package castle;import java.util.HashMap;public class Room {private String description;private HashMap<String, Room> exits = new HashMap<String, Room>();private HashMap<String, String> narration = new HashMap<String, String>();public Room(String description) {this.description = description;}public void setExit(String dir, Room room) {exits.put(dir, room);}public void setNarration(String room, String narr) {narration.put(room, narr);}@Overridepublic String toString(){	return description;}public String getExitDesc() {StringBuffer sb = new StringBuffer();for (String dir : exits.keySet()) {sb.append(dir);sb.append(' ');}return sb.toString();}public Room getExit(String direction) {return exits.get(direction);}public String getNarration(String direction) {return narration.get(direction);}
}

Handler.java

城堡游戏中的添加各种功能的父类模块

package castle;public class Handler {protected Game game;public Handler(Game game) {this.game = game;}public void doCmd(String word) {}public boolean isBye() {return false;}
}

HandlerBye.java

功能模块的子类实现结束功能

package castle;public class HandlerBye extends Handler{public HandlerBye(Game game) {super(game);}@Overridepublic boolean isBye() {return true;}
}

HandlerHelp.java

功能模块的子类实现帮助功能

package castle;public class HandlerHelp extends Handler {public HandlerHelp(Game game) {super(game);}@Overridepublic void doCmd(String word) {System.out.println("迷路了吗？你可以做的命令有：" + game.cmds);System.out.println("如：\tgo east");}}

HandlerGo.java

功能模块的子类实现go功能

package castle;public class HandlerGo extends Handler {public HandlerGo(Game game) {super(game);}@Overridepublic void doCmd(String word) {game.goRoom(word);}}

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学习心得：

• 消除代码复制

  • 提取出来，改为函数。

• 增加可扩展性

  • 可以运行的代码 != 良好的代码
  • 对代码做维护的时候最能看出代码的质量

• 用封装来降低耦合

• Sring每次都String做+时，都会产生新的对象，系统开销较大。

• StringBuffer是可以不断修改的对象。

  • StringBuffer sb = new StringBuffer();
  • sb.append(“haha”);