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cocos2dx音效的实现分析：

1、预加载背景音乐void SimpleAudioEngine::preloadBackgroundMusic(const char* pszFilePath){    std::string fullPath = getFullPathWithoutAssetsPrefix(pszFilePath);    preloadBackgroundMusicJNI(fullPath.c_str());}-->>//得到音乐文件的路径，如果是包里的文件，则去掉assets/前缀static std::string getFullPathWithoutAssetsPrefix(const char* pszFilename){    // Changing file path to full path    //获取文件的路径，以后有时间会分析下CCFileUtils这个类的实现    std::string fullPath = CCFileUtils::sharedFileUtils()->fullPathForFilename(pszFilename);    // Removing `assets` since it isn't needed for the API of playing sound.    size_t pos = fullPath.find("assets/");    if (pos == 0)    {        fullPath = fullPath.substr(strlen("assets/"));    }    return fullPath;}-->>preloadBackgroundMusicJNI：//这里其实就是调用jni的方法：void preloadBackgroundMusicJNI(const char *path)    {        // void playBackgroundMusic(String,boolean)        JniMethodInfo methodInfo;                if (! getStaticMethodInfo(methodInfo, "preloadBackgroundMusic", "(Ljava/lang/String;)V"))        {                        return;        }                jstring stringArg = methodInfo.env->NewStringUTF(path);        methodInfo.env->CallStaticVoidMethod(methodInfo.classID, methodInfo.methodID, stringArg);        methodInfo.env->DeleteLocalRef(stringArg);        methodInfo.env->DeleteLocalRef(methodInfo.classID);    }-->>java端的代码：public static void preloadBackgroundMusic(final String pPath) {		Cocos2dxHelper.sCocos2dMusic.preloadBackgroundMusic(pPath);	}-->>public void preloadBackgroundMusic(final String pPath) {		if ((this.mCurrentPath == null) || (!this.mCurrentPath.equals(pPath))) {			// preload new background music			// release old resource and create a new one			if (this.mBackgroundMediaPlayer != null) {				this.mBackgroundMediaPlayer.release();			}			this.mBackgroundMediaPlayer = this.createMediaplayer(pPath);			// record the path			this.mCurrentPath = pPath;		}	}-->>	private MediaPlayer createMediaplayer(final String pPath) {	//其实就是创建了一个android下的MediaPlayer媒体播放实例，后面的播放，暂停之类	//的，都是这个实例去控制。		MediaPlayer mediaPlayer = new MediaPlayer(); 		try {			if (pPath.startsWith("/")) {				final FileInputStream fis = new FileInputStream(pPath);				mediaPlayer.setDataSource(fis.getFD());				fis.close();			} else {				final AssetFileDescriptor assetFileDescritor = this.mContext.getAssets().openFd(pPath);				mediaPlayer.setDataSource(assetFileDescritor.getFileDescriptor(), assetFileDescritor.getStartOffset(), assetFileDescritor.getLength());			}			mediaPlayer.prepare();			mediaPlayer.setVolume(this.mLeftVolume, this.mRightVolume);		} catch (final Exception e) {			mediaPlayer = null;			Log.e(Cocos2dxMusic.TAG, "error: " + e.getMessage(), e);		}		return mediaPlayer;	}-->>播放背景音乐，这里可以不用预先加载，就直接播放。void SimpleAudioEngine::playBackgroundMusic(const char* pszFilePath, bool bLoop){    std::string fullPath = getFullPathWithoutAssetsPrefix(pszFilePath);    playBackgroundMusicJNI(fullPath.c_str(), bLoop);}