java - 应用程序崩溃引发权限拒绝异常 :reading com. android.providers.media.MediaProvider

Question

我正在开发一个应用程序，需要读取和写入外部存储的权限。我已经在 list 文件以及我的java Activity 文件中写入了所有权限，但我的应用程序在启动时仍然崩溃 抛出异常

权限拒绝:读取 com.android.providers.media.MediaProvider

Manifest File

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.abhi.scrolling_tab">

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

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity
        android:name=".MainActivity"
        android:exported="true"
        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>
    <activity
        android:name=".Fragment_one"
        android:label="Fragment_one"
        android:theme="@style/AppTheme.NoActionBar" />
    <activity
        android:name=".Fragment_two"
        android:label="@string/title_activity_fragment_two"
        android:theme="@style/AppTheme.NoActionBar" />
    <activity
        android:name=".Fragment_three"
        android:label="@string/title_activity_fragment_three"
        android:theme="@style/AppTheme.NoActionBar"></activity>
</application>

Java File

public class Fragment_two extends Fragment {
private RecyclerView recyclerView2;
private List<Model1> modelList;
private myAdapter2 adapter;
private MenuItem menu;


public Fragment_two() {
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.activity_fragment_two, container, false);
    ;
    recyclerView2 = (RecyclerView) view.findViewById(R.id.recycle2);
    int No_of_coloumns = 3;
    recyclerView2.setLayoutManager(new GridLayoutManager(getContext(), No_of_coloumns));
    modelList = getAllaudiofromdevice();
    adapter = new myAdapter2(modelList, (ViewGroup) view);
    recyclerView2.setAdapter(adapter);
    return view;
}

public List<Model1> getAllaudiofromdevice() {
    List<Model1> files = new ArrayList<>();
    try {
        ContentResolver contentResolver = getContext().getContentResolver();
        String selection = MediaStore.Audio.Media.IS_MUSIC;
        Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
        String[] projection = {MediaStore.Audio.AudioColumns.DATA, MediaStore.Audio.AudioColumns.ALBUM, MediaStore.Audio.AudioColumns.ARTIST};
        Cursor c = contentResolver.query(uri, null, selection, null, null);
        if (c != null) {
            while (c.moveToNext()) {
                Model1 model1 = new Model1();
                String path = c.getString(0);
                String album = c.getString(1);
                String artist = c.getString(2);
                String name = path.substring(path.lastIndexOf('/') + 1);
                model1.setName(name);
                model1.setArtist(artist);
                model1.setAlbum(album);
                model1.setPath(path);
                files.add(model1);
            }
            c.close();
        }
    } catch (Exception e) {
        throw e;
    }
    check();
    return files;
}

public void check() {
    if (Build.VERSION.SDK_INT >= 23) {
        if (ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 123);
            return;
        }
    } else {
        getAllaudiofromdevice();
    }
}

@Override
public void onRequestPermissionsResult(int requestcode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    switch (requestcode) {
        case 123:
            if (grantResults[0] != PackageManager.PERMISSION_GRANTED) {
                getAllaudiofromdevice();
            } else {
                Toast.makeText(getContext(), "you have to set permissions", Toast.LENGTH_SHORT).show();
                check();
            }
        default:
            super.onRequestPermissionsResult(requestcode, permissions, grantResults);
    }

}

}

请帮助我摆脱困境。 感谢期待。

Answer 1

仅在授予权限时才进行工作。您的代码包含逻辑错误:

if (grantResults[0] != PackageManager.PERMISSION_GRANTED) { // Mistake here.
    getAllaudiofromdevice();
} //...

此外，在 API 23 上，您的代码在未授予权限时将请求权限，但在已授予权限时将不执行任何操作 (*)。应该是这样的:

public void check() {
    if (Build.VERSION.SDK_INT >= 23 && ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
        // Request permissions if they're not granted on API 23.
        requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 123);
    } else {
        // Do work on API <23 and when permissions were granted on API 23+.
        getAllaudiofromdevice();
    }
}

(*) 根据您调用代码的方式，这确实令人困惑。