找不到媒体播放器文件异常

Question

我正在编写一个基本的 android mp3 播放器应用程序，它使用 MediaPlayer 应用程序播放本地存储在 Android phone 上的 mp3 文件。

但是，每当我尝试调用 MediaPlayer.create() 时，我都会收到 java.io.FileNotFoundException。

我已经检查以确保 mp3 位于正确的路径中，并且我已经在仿真 Android 和我自己的 phone 上尝试运行这个，但是我不断收到相同的错误。

这是我遇到问题的 onCreate 函数：

@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Uri uri = Uri.parse(Environment.getExternalStorageDirectory().getPath() + 
       "/Download/sam_stone.mp3");

    med = MediaPlayer.create(getApplicationContext(), uri);
}

这是我遇到的错误：

java.io.FileNotFoundException: /storage/emulated/0/Download/sam_stone.mp3 (Permission denied) at java.io.FileInputStream.open(Native Method) at java.io.FileInputStream.(FileInputStream.java:146) at android.media.MediaPlayer.setDataSource(MediaPlayer.java:1088) at android.media.MediaPlayer.setDataSource(MediaPlayer.java:1067) at android.media.MediaPlayer.setDataSource(MediaPlayer.java:1009) at android.media.MediaPlayer.setDataSource(MediaPlayer.java:967) at android.media.MediaPlayer.create(MediaPlayer.java:874) at android.media.MediaPlayer.create(MediaPlayer.java:851) at android.media.MediaPlayer.create(MediaPlayer.java:830) at hn.mediaplayer.MainActivity.onCreate(MainActivity.java:48) at android.app.Activity.performCreate(Activity.java:6662) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6077) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)

Answer 1

在AndroidManifest.xml

中添加权限

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
 <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

并在 android 版本 5.0

之上添加运行时间权限

Answer 2

您必须在清单中添加 READ_EXTERNAL_STORAGE 权限。

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

对于 marshmallow 及更高版本，您必须向用户请求 Dangerous permission。

read doc for requesting runtime permission

Answer 3

首先你需要给AndiodManifest.xml文件添加权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

然后在你的 activity

public  boolean isStoragePermissionGranted() {
if (Build.VERSION.SDK_INT >= 23) {
    if (checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
            == PackageManager.PERMISSION_GRANTED) {
        Log.v(TAG,"Permission is granted");
        return true;
    } else {

        Log.v(TAG,"Permission is revoked");
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
        return false;
    }
}
else { 
    Log.v(TAG,"Permission is granted");
    return true;
}}

然后权限结果回调哪里可以恢复任务:

@Override
 public void onRequestPermissionsResult(int requestCode, String[] permissions, 
 int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if(grantResults[0]== PackageManager.PERMISSION_GRANTED){
    Log.v(TAG,"Permission: "+permissions[0]+ " "+grantResults[0]);
}}

找不到媒体播放器文件异常

Media Player File not found exception

android

android-mediaplayer