編輯:關於Android編程
package com.liu.zhen.utils; import android.content.Context; import android.content.res.AssetFileDescriptor; import android.media.MediaPlayer; import android.util.Log; /** * * This class is used for controlling background music * */ public class BackgroundMusic { private static BackgroundMusic backgroundMusic = null; private static final String TAG = "Bg_Music"; private float mLeftVolume; private float mRightVolume; private Context mContext; private MediaPlayer mBackgroundMediaPlayer; private boolean mIsPaused; private String mCurrentPath; private BackgroundMusic(Context context) { this.mContext = context; initData(); } public static BackgroundMusic getInstance(Context context) { if (backgroundMusic == null) { backgroundMusic = new BackgroundMusic(context); } return backgroundMusic; } // 初始化一些數據 private void initData() { mLeftVolume = 0.5f; mRightVolume = 0.5f; mBackgroundMediaPlayer = null; mIsPaused = false; mCurrentPath = null; } /** * 根據path路徑播放背景音樂 * * @param path * :assets中的音頻路徑 * @param isLoop * :是否循環播放 */ public void playBackgroundMusic(String path, boolean isLoop) { if (mCurrentPath == null) { // 這是第一次播放背景音樂--- it is the first time to play background music // 或者是執行end()方法後,重新被叫---or end() was called mBackgroundMediaPlayer = createMediaplayerFromAssets(path); mCurrentPath = path; } else { if (!mCurrentPath.equals(path)) { // 播放一個新的背景音樂--- play new background music // 釋放舊的資源並生成一個新的----release old resource and create a new one if (mBackgroundMediaPlayer != null) { mBackgroundMediaPlayer.release(); } mBackgroundMediaPlayer = createMediaplayerFromAssets(path); // 記錄這個路徑---record the path mCurrentPath = path; } } if (mBackgroundMediaPlayer == null) { Log.e(TAG, "playBackgroundMusic: background media player is null"); } else { // 若果音樂正在播放或已近中斷,停止它---if the music is playing or paused, stop it mBackgroundMediaPlayer.stop(); mBackgroundMediaPlayer.setLooping(isLoop); try { mBackgroundMediaPlayer.prepare(); mBackgroundMediaPlayer.seekTo(0); mBackgroundMediaPlayer.start(); this.mIsPaused = false; } catch (Exception e) { Log.e(TAG, "playBackgroundMusic: error state"); } } } /** * 停止播放背景音樂 */ public void stopBackgroundMusic() { if (mBackgroundMediaPlayer != null) { mBackgroundMediaPlayer.stop(); // should set the state, if not , the following sequence will be // error // play -> pause -> stop -> resume this.mIsPaused = false; } } /** * 暫停播放背景音樂 */ public void pauseBackgroundMusic() { if (mBackgroundMediaPlayer != null && mBackgroundMediaPlayer.isPlaying()) { mBackgroundMediaPlayer.pause(); this.mIsPaused = true; } } /** * 繼續播放背景音樂 */ public void resumeBackgroundMusic() { if (mBackgroundMediaPlayer != null && this.mIsPaused) { mBackgroundMediaPlayer.start(); this.mIsPaused = false; } } /** * 重新播放背景音樂 */ public void rewindBackgroundMusic() { if (mBackgroundMediaPlayer != null) { mBackgroundMediaPlayer.stop(); try { mBackgroundMediaPlayer.prepare(); mBackgroundMediaPlayer.seekTo(0); mBackgroundMediaPlayer.start(); this.mIsPaused = false; } catch (Exception e) { Log.e(TAG, "rewindBackgroundMusic: error state"); } } } /** * 判斷背景音樂是否正在播放 * * @return:返回的boolean值代表是否正在播放 */ public boolean isBackgroundMusicPlaying() { boolean ret = false; if (mBackgroundMediaPlayer == null) { ret = false; } else { ret = mBackgroundMediaPlayer.isPlaying(); } return ret; } /** * 結束背景音樂,並釋放資源 */ public void end() { if (mBackgroundMediaPlayer != null) { mBackgroundMediaPlayer.release(); } // 重新“初始化數據” initData(); } /** * 得到背景音樂的“音量” * * @return */ public float getBackgroundVolume() { if (this.mBackgroundMediaPlayer != null) { return (this.mLeftVolume + this.mRightVolume) / 2; } else { return 0.0f; } } /** * 設置背景音樂的音量 * * @param volume * :設置播放的音量,float類型 */ public void setBackgroundVolume(float volume) { this.mLeftVolume = this.mRightVolume = volume; if (this.mBackgroundMediaPlayer != null) { this.mBackgroundMediaPlayer.setVolume(this.mLeftVolume, this.mRightVolume); } } /** * create mediaplayer for music * * @param path * the path relative to assets * @return */ private MediaPlayer createMediaplayerFromAssets(String path) { MediaPlayer mediaPlayer = null; try { AssetFileDescriptor assetFileDescritor = mContext.getAssets() .openFd(path); mediaPlayer = new MediaPlayer(); mediaPlayer.setDataSource(assetFileDescritor.getFileDescriptor(), assetFileDescritor.getStartOffset(), assetFileDescritor.getLength()); mediaPlayer.prepare(); mediaPlayer.setVolume(mLeftVolume, mRightVolume); } catch (Exception e) { mediaPlayer = null; Log.e(TAG, "error: " + e.getMessage(), e); } return mediaPlayer; } }
HelloWorld的目錄結構有: src:存放應用程序的邏輯代碼,這裡面的代碼是人工寫的gen:存放資源代碼,這裡面的代碼是自動生成的assets:存放mp3等視頻資源
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