背景音乐功能
2 import android.content.Context; 3 import android.content.res.AssetFileDescriptor; 4 import android.media.MediaPlayer; 5 import android.util.Log; 6 7 /** 8 * 9 * This class is used for controlling background music 10 * 11 */ 12 public class BackgroundMusic { 13 14 private static final String TAG = "Bg_Music"; 15 private float mLeftVolume; 16 private float mRightVolume; 17 private Context mContext; 18 private MediaPlayer mBackgroundMediaPlayer; 19 private boolean mIsPaused; 20 private String mCurrentPath; 21 22 public BackgroundMusic(Context context){ 23 this.mContext = context; 24 initData(); 25 } 26 //初始化一些数据 27 private void initData(){ 28 mLeftVolume =0.5f; 29 mRightVolume = 0.5f; 30 mBackgroundMediaPlayer = null; 31 mIsPaused = false; 32 mCurrentPath = null; 33 } 34 35 /** 36 * 根据path路径播放背景音乐 37 * @param path :assets中的音频路径 38 * @param isLoop :是否循环播放 39 */ 40 public void playBackgroundMusic(String path, boolean isLoop){ 41 if (mCurrentPath == null){ 42 //这是第一次播放背景音乐--- it is the first time to play background music 43 //或者是执行end()方法后,重新被叫---or end() was called 44 mBackgroundMediaPlayer = createMediaplayerFromAssets(path); 45 mCurrentPath = path; 46 } 47 else { 48 if (! mCurrentPath.equals(path)){ 49 //播放一个新的背景音乐--- play new background music 50 //释放旧的资源并生成一个新的----release old resource and create a new one 51 if (mBackgroundMediaPlayer != null){ 52 mBackgroundMediaPlayer.release(); 53 } 54 mBackgroundMediaPlayer = createMediaplayerFromAssets(path); 55 //记录这个路径---record the path 56 mCurrentPath = path; 57 } 58 } 59 60 if (mBackgroundMediaPlayer == null){ 61 Log.e(TAG, "playBackgroundMusic: background media player is null"); 62 } else { 63 // 若果音乐正在播放或已近中断,停止它---if the music is playing or paused, stop it 64 mBackgroundMediaPlayer.stop(); 65 mBackgroundMediaPlayer.setLooping(isLoop); 66 try { 67 mBackgroundMediaPlayer.prepare(); 68 mBackgroundMediaPlayer.seekTo(0); 69 mBackgroundMediaPlayer.start(); 70 this.mIsPaused = false; 71 } catch (Exception e){ 72 Log.e(TAG, "playBackgroundMusic: error state"); 73 } 74 } 75 } 76 77 /** 78 * 停止播放背景音乐 79 */ 80 public void stopBackgroundMusic(){ 81 if (mBackgroundMediaPlayer != null){ 82 mBackgroundMediaPlayer.stop(); 83 // should set the state, if not , the following sequence will be error 84 // play -> pause -> stop -> resume 85 this.mIsPaused = false; 86 } 87 } 88 /** 89 * 暂停播放背景音乐 90 */ 91 public void pauseBackgroundMusic(){ 92 if (mBackgroundMediaPlayer != null && mBackgroundMediaPlayer.isPlaying()){ 93 mBackgroundMediaPlayer.pause(); 94 this.mIsPaused = true; 95 } 96 } 97 /** 98 * 继续播放背景音乐 99 */ 100 public void resumeBackgroundMusic(){ 101 if (mBackgroundMediaPlayer != null && this.mIsPaused){ 102 mBackgroundMediaPlayer.start(); 103 this.mIsPaused = false; 104 } 105 } 106 /** 107 * 重新播放背景音乐 108 */ 109 public void rewindBackgroundMusic(){ 110 if (mBackgroundMediaPlayer != null){ 111 mBackgroundMediaPlayer.stop(); 112 try { 113 mBackgroundMediaPlayer.prepare(); 114 mBackgroundMediaPlayer.seekTo(0); 115 mBackgroundMediaPlayer.start(); 116 this.mIsPaused = false; 117 } catch (Exception e){ 118 Log.e(TAG, "rewindBackgroundMusic: error state"); 119 } 120 } 121 } 122 /** 123 * 判断背景音乐是否正在播放 124 * @return:返回的boolean值代表是否正在播放 125 */ 126 public boolean isBackgroundMusicPlaying(){ 127 boolean ret = false; 128 if (mBackgroundMediaPlayer == null){ 129 ret = false; 130 } else { 131 ret = mBackgroundMediaPlayer.isPlaying(); 132 } 133 return ret; 134 } 135 /** 136 * 结束背景音乐,并释放资源 137 */ 138 public void end(){ 139 if (mBackgroundMediaPlayer != null){ 140 mBackgroundMediaPlayer.release(); 141 } 142 //重新“初始化数据” 143 initData(); 144 } 145 /** 146 * 得到背景音乐的“音量” 147 * @return 148 */ 149 public float getBackgroundVolume(){ 150 if (this.mBackgroundMediaPlayer != null){ 151 return (this.mLeftVolume + this.mRightVolume) / 2; 152 } else { 153 return 0.0f; 154 } 155 } 156 /** 157 * 设置背景音乐的音量 158 * @param volume:设置播放的音量,float类型 159 */ 160 public void setBackgroundVolume(float volume){ 161 this.mLeftVolume = this.mRightVolume = volume; 162 if (this.mBackgroundMediaPlayer != null){ 163 this.mBackgroundMediaPlayer.setVolume(this.mLeftVolume, this.mRightVolume); 164 } 165 } 166 /** 167 * create mediaplayer for music 168 * @param path the path relative to assets 169 * @return 170 */ 171 private MediaPlayer createMediaplayerFromAssets(String path){ 172 MediaPlayer mediaPlayer = null; 173 try{ 174 AssetFileDescriptor assetFileDescritor = mContext.getAssets().openFd(path); 175 mediaPlayer = new MediaPlayer(); 176 mediaPlayer.setDataSource(assetFileDescritor.getFileDescriptor(), 177 assetFileDescritor.getStartOffset(), assetFileDescritor.getLength()); 178 mediaPlayer.prepare(); 179 mediaPlayer.setVolume(mLeftVolume, mRightVolume); 180 }catch (Exception e) { 181 mediaPlayer = null; 182 Log.e(TAG, "error: " + e.getMessage(), e); 183 } 184 return mediaPlayer; 185 } 186 } 187 188