如何添加Android返回键的退出功能
环境:Cocos2dxv3.5
经网上搜索资料知道有两种方法可以实现Android返回键的退出功能,下面分别说明。
1、修改java代码
首先,在Cocos2dx的源文件中找到Cocos2dxGLSurfaceView.java文件,它的路径是:cocos2d\cocos\platform\android\java\src\org\cocos2dx\lib\Cocos2dxGLSurfaceView.java。注意要在自己的工程文件里面找这个文件。
打开Cocos2dxGLSurfaceView.java,找到其中的onKeyDown函数:
@Override public boolean onKeyDown(final int pKeyCode, final KeyEvent pKeyEvent) { switch (pKeyCode) { case KeyEvent.KEYCODE_BACK: Cocos2dxVideoHelper.mVideoHandler.sendEmptyMessage(Cocos2dxVideoHelper.KeyEventBack); case KeyEvent.KEYCODE_MENU: case KeyEvent.KEYCODE_DPAD_LEFT: case KeyEvent.KEYCODE_DPAD_RIGHT: case KeyEvent.KEYCODE_DPAD_UP: case KeyEvent.KEYCODE_DPAD_DOWN: case KeyEvent.KEYCODE_ENTER: case KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE: case KeyEvent.KEYCODE_DPAD_CENTER: this.queueEvent(new Runnable() { @Override public void run() { Cocos2dxGLSurfaceView.this.mCocos2dxRenderer.handleKeyDown(pKeyCode); } }); return true; default: return super.onKeyDown(pKeyCode, pKeyEvent); }}
修改为如下代码(在caseKeyEvent.KEYCODE_BACK分支中添加返回false的语句,表示不处理按键消息):
@Override public boolean onKeyDown(final int pKeyCode, final KeyEvent pKeyEvent) { switch (pKeyCode) { case KeyEvent.KEYCODE_BACK: Cocos2dxVideoHelper.mVideoHandler.sendEmptyMessage(Cocos2dxVideoHelper.KeyEventBack);return false; case KeyEvent.KEYCODE_MENU: case KeyEvent.KEYCODE_DPAD_LEFT: case KeyEvent.KEYCODE_DPAD_RIGHT: case KeyEvent.KEYCODE_DPAD_UP: case KeyEvent.KEYCODE_DPAD_DOWN: case KeyEvent.KEYCODE_ENTER: case KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE: case KeyEvent.KEYCODE_DPAD_CENTER: this.queueEvent(new Runnable() { @Override public void run() { Cocos2dxGLSurfaceView.this.mCocos2dxRenderer.handleKeyDown(pKeyCode); } }); return true; default: return super.onKeyDown(pKeyCode, pKeyEvent); } }
其次,找到AppActivity.java文件,其路径为:proj.android\src\org\cocos2dx\cpp\AppActivity.java。它的代码如下:
package org.cocos2dx.cpp;import org.cocos2dx.lib.Cocos2dxActivity;public class AppActivity extends Cocos2dxActivity {}
修改为(添加onKeyDown方法,处理返回键按下事件):
package org.cocos2dx.cpp;import org.cocos2dx.lib.Cocos2dxActivity;import org.cocos2dx.lib.Cocos2dxGLSurfaceView;import android.app.Activity;import android.os.Bundle;import android.view.KeyEvent;import android.widget.Toast;public class AppActivity extends Cocos2dxActivity {private long mKeyTime = 0;public boolean onKeyDown(int keyCode, KeyEvent event) {if (KeyEvent.KEYCODE_BACK == keyCode && KeyEvent.ACTION_DOWN == keyCode) {if ((System.currentTimeMillis() - mKeyTime) > 2000) {mKeyTime = System.currentTimeMillis();Toast.makeText(getApplicationContext(), "要离开游戏吗?", Toast.LENGTH_SHORT).show();} else {finish();System.exit(0);}return true;}return super.onKeyDown(keyCode, event);}}
最终,重新编译生成apk文件,按下Android手机的返回键,就能实现退出游戏了。但是经测试,游戏会直接退出,而不会出现提示,以后再探索。
2、在Cocos2dx中添加代码
第一步,在Cocos2dx的场景类中添加虚方法:
virtual void onKeyReleased(cocos2d::EventKeyboard::KeyCode keyCode, cocos2d::Event* event);
第二步,实现该虚方法:
void HelloWorld::onKeyReleased(EventKeyboard::KeyCode keyCode, Event* event){switch (keyCode){case EventKeyboard::KeyCode::KEY_BACK://返回键//退出游戏#if (CC_TARGET_PLATFORM == CC_PLATFORM_WP8) || (CC_TARGET_PLATFORM == CC_PLATFORM_WINRT)MessageBox("You pressed the close button. Windows Store Apps do not implement a close button.","Alert");return;#endifDirector::getInstance()->end();#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)exit(0);#endifbreak;default:break;}}
第三步,在场景类的init方法中添加按键事件监听:
//Android按键监听auto keyboardListener = EventListenerKeyboard::create();keyboardListener->onKeyReleased = CC_CALLBACK_2(HelloWorld::onKeyReleased, this);this->getEventDispatcher()->addEventListenerWithSceneGraphPriority(keyboardListener, this);
最后,重新编译,同样能够实现退出的效果。
结论:java代码对Android系统有直接的操作,因此它比Cocos2dx的退出更直接,两种方法再次启动游戏的时候会从头加载资源。另外,官方demo中指出,第2种方法“Only avaliable on Desktop and Android”,即仅仅对WIndows平台和Android平台有效,并且需要在onKeyReleased事件中处理消息才能正确响应。
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