如何获得读取外部存储权限？

Posted 2023-03-14

【中文标题】如何获得读取外部存储权限？

【英文标题】：How to get read external storage permissions?

【发布时间】：2017-08-26 05:01:31

【问题描述】：

我正在为 android 开发一个 mp3 播放器应用程序，但遇到与用户权限相关的错误（READ_EXTERNAL_STORAGE）

这是我请求权限的代码：

int permissionCheck = ContextCompat.checkSelfPermission(PlayListActivity.this,
                Manifest.permission.READ_EXTERNAL_STORAGE);

        if (ContextCompat.checkSelfPermission(PlayListActivity.this,
                Manifest.permission.READ_EXTERNAL_STORAGE)
                != PackageManager.PERMISSION_GRANTED) 


            // OPCIONAL(explicaciones de poque pedimos los permisos)
            if (ActivityCompat.shouldShowRequestPermissionRationale(PlayListActivity.this,
                    Manifest.permission.READ_EXTERNAL_STORAGE)) 

             else 
                //pedir permisos
                ActivityCompat.requestPermissions(PlayListActivity.this,
                        new String[]Manifest.permission.READ_EXTERNAL_STORAGE,
                        permissionCheck);

这是剩下的代码：

ArrayList<HashMap<String, String>> songsListData = new ArrayList<HashMap<String, String>>();

    SongsManager plm = new SongsManager(PlayListActivity.this);
    // get all songs from sdcard
    this.songsList = plm.getPlayList();

    // looping through playlist
    for (int i = 0; i < songsList.size(); i++) 
        // creating new HashMap
        HashMap<String, String> song = songsList.get(i);

        // adding HashList to ArrayList
        songsListData.add(song);
    

    // se añaden las canciones a la ListView mediante un adapter utilizando el layout playlist_item
    ListAdapter adapter = new SimpleAdapter(this, songsListData,
            R.layout.playlist_item, new String[]  "songTitle" , new int[] 
            R.id.songTitle );

    setListAdapter(adapter);

这是错误：

03-31 22:09:16.159 2258-2258/com.androidchatapp E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.androidchatapp, PID: 2258
    java.lang.RuntimeException: Unable to start activity ComponentInfocom.androidchatapp/com.androidchatapp.PlayListActivity: java.lang.SecurityException: Permission Denial: reading com.android.providers.media.MediaProvider uri content://media/external/audio/media from pid=2258, uid=10184 requires android.permission.READ_EXTERNAL_STORAGE, or grantUriPermission()
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2434)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2494)
    at android.app.ActivityThread.access$900(ActivityThread.java:153)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1347)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5451)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
    Caused by: java.lang.SecurityException: Permission Denial: reading com.android.providers.media.MediaProvider uri content://media/external/audio/media from pid=2258, uid=10184 requires android.permission.READ_EXTERNAL_STORAGE, or grantUriPermission()
    at android.os.Parcel.readException(Parcel.java:1620)
    at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:183)
    at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:135)
    at android.content.ContentProviderProxy.query(ContentProviderNative.java:421)
    at android.content.ContentResolver.query(ContentResolver.java:493)
    at android.content.ContentResolver.query(ContentResolver.java:435)
    at com.androidchatapp.SongsManager.getPlayList(SongsManager.java:48)
    at com.androidchatapp.PlayListActivity.onCreate(PlayListActivity.java:65)
    at android.app.Activity.performCreate(Activity.java:6323)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2387)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2494)
    at android.app.ActivityThread.access$900(ActivityThread.java:153)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1347)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5451)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

【问题讨论】：

您是否在清单文件中添加了权限？

【参考方案1】：

你已经从代码中请求了权限，但是你可能忘记在清单文件中添加这个权限标签

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

【参考方案2】：

Android从Marshmallow OS引入了runtime权限，所以我们需要用Manifest权限来实现runtime权限。如果 CompileSdkVersion = 23

您可以在屏幕打开时（在 onCreate() 中）或按钮的单击事件（Like -play Music）请求权限

使用此方法检查运行时权限是否启用

 private static final int READ_STORAGE_PERMISSION_REQUEST_CODE = 41;
 public boolean checkPermissionForReadExtertalStorage() 
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) 
        int result = context.checkSelfPermission(android.Manifest.permission.READ_EXTERNAL_STORAGE);
        return result == PackageManager.PERMISSION_GRANTED;
    
    return false;
 

如果它返回 false 然后调用下面的方法，它将显示一个对话框以获取权限

 public void requestPermissionForReadExtertalStorage() throws Exception 
        try 
            ActivityCompat.requestPermissions((Activity) context, new String[]android.Manifest.permission.READ_EXTERNAL_STORAGE,
                    READ_STORAGE_PERMISSION_REQUEST_CODE);
         catch (Exception e) 
            e.printStackTrace();
            throw e;
        
    

【讨论】：

如果有人需要知道：static final Integer READ_STORAGE_PERMISSION_REQUEST_CODE=0x3;您可以使用任何数字。