背景音乐播放

来源：互联网发布：国内导演排行榜知乎编辑：程序博客网时间：2024/05/04 04:32
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 final String TAG = "Bg_Music";      private float mLeftVolume;      private float mRightVolume;      private Context mContext;      private MediaPlayer mBackgroundMediaPlayer;      private boolean mIsPaused;      private String mCurrentPath;        public BackgroundMusic(Context context){          this.mContext = context;          initData();      }      //初始化一些数据      private void initData(){              mLeftVolume =0.5f;              mRightVolume = 0.5f;              mBackgroundMediaPlayer = null;              mIsPaused = false;              mCurrentPath = null;     }            /**       * 根据path路径播放背景音乐       * @param path :assets中的音频路径       * @param isLoop  :是否循环播放       */      public void playBackgroundMusic(String path, boolean isLoop){          if (mCurrentPath == null){              //这是第一次播放背景音乐--- it is the first time to play background music              //或者是执行end()方法后，重新被叫---or end() was called              mBackgroundMediaPlayer = createMediaplayerFromAssets(path);                  mCurrentPath = path;          }           else {              if (! mCurrentPath.equals(path)){                  //播放一个新的背景音乐--- play new background music                  //释放旧的资源并生成一个新的----release old resource and create a new one                  if (mBackgroundMediaPlayer != null){                      mBackgroundMediaPlayer.release();                                  }                                  mBackgroundMediaPlayer = createMediaplayerFromAssets(path);                  //记录这个路径---record the path                  mCurrentPath = path;                }         }                 if (mBackgroundMediaPlayer == null){              Log.e(TAG, "playBackgroundMusic: background media player is null");          } else {                      // 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              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");             }                      }      }            /**       * 停止播放背景音乐       */      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;          }      }      /**       * 暂停播放背景音乐       */      public void pauseBackgroundMusic(){                  if (mBackgroundMediaPlayer != null && mBackgroundMediaPlayer.isPlaying()){              mBackgroundMediaPlayer.pause();              this.mIsPaused = true;          }      }      /**       * 继续播放背景音乐       */     public void resumeBackgroundMusic(){         if (mBackgroundMediaPlayer != null && this.mIsPaused){             mBackgroundMediaPlayer.start();             this.mIsPaused = false;         }     }     /**      * 重新播放背景音乐      */     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");             }                     }     }     /**      * 判断背景音乐是否正在播放      * @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;     }     /**      * 结束背景音乐，并释放资源      */     public void end(){         if (mBackgroundMediaPlayer != null){             mBackgroundMediaPlayer.release();         }         //重新“初始化数据”         initData();     }     /**      * 得到背景音乐的“音量”      * @return      */     public float getBackgroundVolume(){         if (this.mBackgroundMediaPlayer != null){             return (this.mLeftVolume + this.mRightVolume) / 2;         } else {             return 0.0f;         }     }     /**      * 设置背景音乐的音量      * @param volume：设置播放的音量，float类型      */     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;     } }
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