Java版AVG游戏开发入门[0]——游戏模式转换中的事件交互

示例程序下载地址：http://download.csdn.net/source/999273（源码在jar内）

AVG，即Adventure Game，可以直译为[冒险游戏]。但是通常情况下我们说AVG是指[文字冒险游戏]，也有人更直白的解释成自己选择路线和结局的电子小说，与硬砍硬杀的RPG或者揉破键盘的ACT不同，AVG多以解谜或文字游戏等脑力攻关推动剧情发展。现在日本流行的ADV，可以看作是AVG英文全称的不同缩写方式，大体上讲，AVG == ADV。

由于商业化需要，现代主流的AVG往往是GalGame，也就是少女游戏，或称少女恋爱游戏，但GalGame != AVG，只是下属分支中的一环罢了，AVG包含GalGame，但GalGame并不能完全代表AVG/ADV。另外关于GalGame的详细介绍，在若木民喜《只有神才知道的世界》中演绎的相当生动，有兴趣的可以自己去看看~

就技术角度而言，AVG开发可以算得所有游戏类型中最容易的。一款简单AVG游戏的制作难度甚至在贪食蛇、俄罗斯方块之下。由于实现的简易性，导致AVG的开发重心往往着重于策划及美工，程序员的作用则微乎其微。同时也正因AVG开发的门坎约等于0，所以此类型的同人游戏之多即可堪称世界之冠。另外，AVG开发工具普及的也促进了AVG的量产化。利用工具，即始是小说作者、漫画家等非软件专业出身的人士，往往也能轻易制作出*的AVG大作。（顺便一提，目前我所见过最好的AVG制作工具是鬼子的livemaker，采用类似思维导图的方式构造整个游戏，很多轻小说作者乃至网络漫画家用它制作自己作品的宣传游戏。但就技术角度上说，livemaker的开发依旧没什么难度......）

由于AVG的大泛滥，通常仅有文字、图片及语音的AVG往往无法满足用户需求（H除外-_-）。我们每每可在AVG游戏类型后发现个+号，比如《樱花大战》是AVG+SLG，《生化危机》是AVG+ACT。所以客观上说，AVG开发仅仅能进行字图的交互是不够的，还要解决多模块组件的协调问题。

在Java桌面应用开发中,我们都知道绘图是极为简单的，有Image、Graphics两个对象就可以Paint一个图形，即使图形对象再多，最后它们也必须统一在一个Paint中，所以Java中不存在图像的交互问题。

但问题在于，图像的显示可以统一，但是触发图像变化的事件却是很难统一的。比如现在有需求如下，在AVG模式中，触发键盘事件上、下、左、右时为控制画面的前进、后退，切换模式到SLG模式后，设定上、下、左、右是光标移动，那么如果我要在程序中实现，就必须记录当前模式，而后根据不同模式调用事件，再反馈到图形上。如果只有几个事件的区别，我们当然可以很容易用分支来实现；问题是，随着游戏规模的加大，这些分支将成几何倍数增多，单纯的分支判定到最后只能忙于应付，落个费力不讨好。

其实在这时，我们大可以使用一些技巧来轻松解决问题。

示例如下：

首先，我们构造一个接口，命名为IControl，继承鼠标及键盘监听，并在其中设定两个抽象方法：

package org.loon.simple.avg; import java.awt.Graphics; import java.awt.event.KeyListener; import java.awt.event.MouseListener; import java.awt.event.MouseMotionListener; /** * Copyright 2008 - 2009 * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. * * @project loonframework * @author chenpeng * @email：ceponline@yahoo.com.cn * @version 0.1 */ public interface IControl extends MouseListener, MouseMotionListener, KeyListener { public abstract void draw(final Graphics g); public abstract IControl invoke(); }

而后，再构造一个接口，命名为IAVG，同样继承鼠标及键盘监听，并在其中设定三个抽象方法，用以操作IControl接口：

package org.loon.simple.avg; import java.awt.Graphics; import java.awt.event.KeyListener; import java.awt.event.MouseListener; import java.awt.event.MouseMotionListener; /** * Copyright 2008 - 2009 * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. * * @project loonframework * @author chenpeng * @email：ceponline@yahoo.com.cn * @version 0.1 */ public interface IAVG extends MouseListener, MouseMotionListener, KeyListener { public abstract void draw(final Graphics g); public abstract IControl getControl(); public abstract void setControl(final IControl control); }

再后，制作一个显示图像用组件，命名为AVGCanva，继承自Canvas。

package org.loon.simple.avg; import java.awt.Canvas; import java.awt.Graphics; /** * Copyright 2008 - 2009 * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. * * @project loonframework * @author chenpeng * @email：ceponline@yahoo.com.cn * @version 0.1 */ public class AVGCanvas extends Canvas { /** * */ private static final long serialVersionUID = 1982278682597393958L; private boolean start; private IAVG avg; public AVGCanvas(IAVG handler) { this.avg = handler; this.start = false; this.addKeyListener(handler); this.addMouseListener(handler); this.addMouseMotionListener(handler); } public void update(Graphics g) { paint(g); } public void paint(Graphics g) { if (this.start) { this.avg.draw(g); } } public void startPaint() { this.start = true; } public void endPaint() { this.start = false; } }

这段代码中的paint方法中并没有现成的方法，而是调用了IAVG接口的draw。紧接着，我们再设定一个AVGFrame用以加载AVGCanvas。

package org.loon.simple.avg; import java.awt.Color; import java.awt.Dimension; import java.awt.Frame; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; /** * Copyright 2008 - 2009 * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. * * @project loonframework * @author chenpeng * @email：ceponline@yahoo.com.cn * @version 0.1 */ public class AVGFrame extends Frame implements Runnable { /** * */ private static final long serialVersionUID = 198284399945549558L; private IAVG avg; private AVGCanvas canvas; private boolean fps; private String titleName; private Thread mainLoop; public AVGFrame(String titleName, int width, int height) { this(new AVG(), titleName, width, height); } public AVGFrame(IAVG avg, String titleName, int width, int height) { super(titleName); Lib.WIDTH = width; Lib.HEIGHT = height; this.avg = avg; this.titleName = titleName; this.addKeyListener(avg); this.setPreferredSize(new Dimension(width + 5, height + 25)); this.initCanvas(Lib.WIDTH, Lib.HEIGHT); this.pack(); this.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); this.setResizable(false); this.setLocationRelativeTo(null); this.setVisible(true); } public void run() { gameLoop(); } /** * 开始循环窗体图像 * */ private synchronized void gameLoop() { canvas.startPaint(); long second = 0L; int moveCount = 0; // 循环绘制 for (;;) { long start = System.currentTimeMillis(); this.paintScreen(); long end = System.currentTimeMillis(); long time = end - start; long sleepTime = 20L - time; if (sleepTime < 0L) sleepTime = 0L; try { Thread.sleep(sleepTime); } catch (InterruptedException e) { e.printStackTrace(); } if (this.fps) { moveCount++; second += System.currentTimeMillis() - start; if (second >= 1000L) { this.setTitle(new StringBuilder(titleName).append(" FPS:") .append(moveCount).toString()); moveCount = 0; second = 0L; } } } } /** * 启动游戏循环 * */ public void mainLoop() { this.mainLoop = new Thread(this); this.mainLoop.start(); } /** * 初始化背景帆布 * * @param width * @param height */ private void initCanvas(final int width, final int height) { canvas = new AVGCanvas(avg); canvas.setBackground(Color.black); canvas.setPreferredSize(new Dimension(width, height)); this.add(canvas); } public IAVG getAVG() { return this.avg; } protected void processWindowEvent(WindowEvent e) { super.processWindowEvent(e); } public synchronized void paintScreen() { canvas.repaint(); } public boolean isShowFPS() { return fps; } public void setShowFPS(boolean fps) { this.fps = fps; } public Thread getMainLoop() { return mainLoop; } public String getTitleName() { return titleName; } }

我们可以看到，在本例鼠标键盘事件及图像绘制完全通过接口方式实现。此时，只要让不同组件统一实现IControl接口，便可以轻松转换事件及图像的绘制。也正是我们都再熟悉不过的MVC模式中，通过Event导致Controller改变Model及View的基本原理。

下一回，我们将具体讲解一个AVG游戏实现的基本流程。

示例代码界面如下图：

Java版AVG游戏开发入门[0]——游戏模式转换中的事件交互