Question

我正在尝试访问 externalStorage 中的mp3文件，这是我的代码：

    public class MainActivity extends AppCompatActivity {
  private LinearLayout viewL;
    private String[] STAR = { "*" };
    String fullpath;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        viewL = (LinearLayout) findViewById(R.id.linear);

    try{

        String provider = "com.android.providers.media.MediaProvider";
        Uri uri = Uri.parse("content://media/external/audio/media");

        grantUriPermission(provider, uri, Intent.FLAG_GRANT_READ_URI_PERMISSION);
        grantUriPermission(provider, uri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
        grantUriPermission(provider, uri, Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION);

        Cursor cursor;
        Uri allsongsuri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
        String selection = android.provider.MediaStore.Audio.Media.IS_MUSIC + " != 0";
        cursor = getContentResolver().query(allsongsuri, STAR, selection, null, null);

        for(int i =0;i<1;i++){
            cursor.moveToFirst();
      fullpath = cursor.getString(cursor
                    .getColumnIndex(MediaStore.Audio.Media.DATA));
        }
        MediaPlayer mp = new MediaPlayer();
        Uri myUri = Uri.parse(fullpath);
     mp.setDataSource(this,myUri);
        mp.prepare();
        mp.start();



    }
        catch (Exception e){
            Snackbar.make(viewL,e.toString(),Snackbar.LENGTH_LONG).show();
        }

    }


}

这是我的manifestFile：

 <?xml version="1.0" encoding="utf-8"?>
<manifest package="com.grassa"
          xmlns:android="http://schemas.android.com/apk/res/android">
  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission>
    <uses-permission android:name="android.permission.STORAGE" />
    <uses-permission android:name="android.permission.MANAGE_DOCUMENTS" />


    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>

</manifest>

这是我的logcat：

Writing exception to parcel
                                             java.lang.SecurityException: Permission Denial: reading com.android.providers.media.MediaProvider uri content://media/external/audio/media from pid=20241, uid=10113 requires android.permission.READ_EXTERNAL_STORAGE, or grantUriPermission()
                                                 at android.content.ContentProvider.enforceReadPermissionInner(ContentProvider.java:605)
                                                 at android.content.ContentProvider$Transport.enforceReadPermission(ContentProvider.java:480)
                                                 at android.content.ContentProvider$Transport.query(ContentProvider.java:211)
                                                 at android.content.ContentProviderNative.onTransact(ContentProviderNative.java:112)
                                                 at android.os.Binder.execTransact(Binder.java:453)

正如您所看到的，我已经添加了所有必需的权限，但我仍然获得权限拒绝错误有人可以帮我解决这个问题吗？ THANKYOU

Answer 1

如果您在marshmallow上运行它，则需要在运行时请求权限。

这是官方文件：http://developer.android.com/training/permissions/requesting.html

您必须使用ContextCompat.checkSelfPermission功能检查权限。然后，如果您没有获得许可，

通过ActivityCompat.requestPermissions方法申请并实施

public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults)方法来接收用户结果。

Answer 2

如果设备运行的是Android 5.1或更低版本，或者您的应用的目标SDK为22或更低：如果您在清单中列出了危险权限，则用户必须在安装应用时授予权限;如果他们不授予权限，系统根本不会安装应用程序。

如果设备运行的是Android 6.0或更高版本，并且您的应用的目标SDK为23或更高：应用必须列出清单中的权限，并且必须在应用运行时请求其所需的每个危险权限。用户可以授予或拒绝每个权限，即使用户拒绝权限请求，应用程序也可以继续以有限的功能运行。使用下面的代码，

if (ContextCompat.checkSelfPermission(thisActivity,
            Manifest.permission.READ_CONTACTS)
    != PackageManager.PERMISSION_GRANTED) {

// Should we show an explanation?
if (ActivityCompat.shouldShowRequestPermissionRationale(thisActivity,
        Manifest.permission.READ_CONTACTS)) {

    // Show an expanation to the user *asynchronously* -- don't block
    // this thread waiting for the user's response! After the user
    // sees the explanation, try again to request the permission.

} else {

    // No explanation needed, we can request the permission.

    ActivityCompat.requestPermissions(thisActivity,
            new String[]{Manifest.permission.READ_CONTACTS},
            MY_PERMISSIONS_REQUEST_READ_CONTACTS);

    // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
    // app-defined int constant. The callback method gets the
    // result of the request.
}
}

并通过

处理您的权限状态

@Override
public void onRequestPermissionsResult(int requestCode,
    String permissions[], int[] grantResults) {
    switch (requestCode) {
    case MY_PERMISSIONS_REQUEST_READ_CONTACTS: {
        // If request is cancelled, the result arrays are empty.
        if (grantResults.length > 0
            && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

            // permission was granted, yay! Do the
            // contacts-related task you need to do.

        } else {

            // permission denied, boo! Disable the
            // functionality that depends on this permission.
        }
        return;
    }

    // other 'case' lines to check for other
    // permissions this app might request
}
}

来源：http://developer.android.com/training/permissions/requesting.html

MediaStore权限被拒绝错误android

2 个答案: