android实现背景音乐播放

来源：互联网发布：淘宝开店未认证编辑：程序博客网时间：2024/05/22 03:23
参考了一下网上比人写的，再使用的时候是放在新开的线程中来播放音乐的，后来发现每次进入Activity后就会重复开始一个音乐播放的声音。为了避免重复开启播放功能我在原来代码的基础上增加了单例模式。这样就避免了出现重复播放。
    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;          }      }
原文地址：http://blog.csdn.net/liu1164316159/article/details/40400529
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