Question

我将我的mp3文件放在一个文件夹中并将其保存在特定路径中，我无法从我的代码中播放该文件。怎么玩？

String filePath = (File.separator+"storage"+File.separator+"emulated"+File.separator+"0"+File.separator + "sdcard" + File.separator + "Android" + File.separator + "obb" + File.separator + "convertMp3ToDb" + File.separator + "ldoce6_hwd_gb" + File.separator + fileName).toString();
                final File file = new File(filePath);
                Uri uri_path = Uri.fromFile(file);
                if (uri_path!=null) {
                    try {
                        mediaPlayer.setDataSource(uri_path.getPath());
                        mediaPlayer.prepare();                           
                        mediaPlayer.start();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

我的日志猫错误是：

 System.err: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaPlayer.setDataSource(java.lang.String)' on a null object reference
W/System.err:     at com.mobifusion.android.ldoce5.Fragment.DetailPageFragment.playSound(DetailPageFragment.java:523)
07-14 13:03:27.896 28522-30026/com.mobifusion.android.ldoce5 W/System.err:     at com.mobifusion.android.ldoce5.Util.JavaScriptInterface.checkUsUkExampleSoundButton(JavaScriptInterface.java:292)
07-14 13:03:27.896 28522-30026/com.mobifusion.android.ldoce5 W/System.err:     at org.chromium.base.SystemMessageHandler.nativeDoRunLoopOnce(Native Method)
07-14 13:03:27.896 28522-30026/com.mobifusion.android.ldoce5 W/System.err:     at org.chromium.base.SystemMessageHandler.handleMessage(SystemMessageHandler.java:39)
07-14 13:03:27.896 28522-30026/com.mobifusion.android.ldoce5 W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:102)
07-14 13:03:27.896 28522-30026/com.mobifusion.android.ldoce5 W/System.err:     at android.os.Looper.loop(Looper.java:145)
07-14 13:03:27.896 28522-30026/com.mobifusion.android.ldoce5 W/System.err:     at android.os.HandlerThread.run(HandlerThread.java:61)

Answer 1

像这样创建路径

File path = Environment.getExternalStoragePublicDirectory("/FolderName/SubFolder/xyz.mp3");

你不必创建或解析它到uri

final File file = new File(path);
  if (file !=null) {
       try {
             // make sure mediaPlayer is not null here if(mediaPlayer != null)
             // use prepareAsync which will let you know when media is ready to be played
             // Also add mediaPlayer Exceptions in catch block
             if(mediaPlayer != null){
                 mediaPlayer.setDataSource(file.getPath());
                 mediaPlayer.setOnPreparedListener(this);
                 mediaPlayer.prepareAsync();
             }else{
                // you can use context in mediaPlayer constructor but if dont have use like below
                 mediaPlayer = new MediaPlayer(ActivityName.this);
                 mediaPlayer.setDataSource(file.getPath());
                 mediaPlayer.setOnPreparedListener(this);
                 mediaPlayer.prepareAsync();
             }
            } catch (IOException e) {
               e.printStackTrace();
            }



public void onPrepared(MediaPlayer player) {
    mediaPlayer.start();
}

了解mediaPlayer架构here.

Answer 2

1.需要在prepare()之前添加start()

   MediaPlayer mp=new MediaPlayer();  
    try{  
        mp.setDataSource(uri_path.getPath());  
        mp.prepare();  
        mp.start();  

     }
  catch(Exception e){
    e.printStackTrace();
   }

检查文件路径是否正确。

这可能有助于你

Answer 3

这就是你需要初始化和启动媒体播放器的方式。

MediaPlayer mediaPlayer = new MediaPlayer();
mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
mediaPlayer.setDataSource(myUri);
mediaPlayer.prepare();
mediaPlayer.start();

来源googel documentation

我无法在android中的本地存储中播放mp3文件

3 个答案: