读写外部存储权限不起作用

Question

在我的应用程序中，我想获得用户在外部存储上读取和写入数据的权限，我已将权限标签放在我的清单中，如下所示。 但是，当安装应用程序或运行以及需要读取或写入存储时，不会从用户那里获得任何权限，并且读取和写入内存不起作用，直到我手动转到设置应用程序访问并启用对内存的访问。

我的清单是这样的：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="javadi60.saber.storeassistant">

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

   <application
      android:allowBackup="true"
      android:dialogTheme="@style/CustomDialog"
      android:icon="@mipmap/myappicon"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
          <intent-filter>
              <action android:name="android.intent.action.MAIN" />
              <category android:name="android.intent.category.LAUNCHER" />
          </intent-filter>
      </activity>
      <activity android:name=".insertData" />
      <activity android:name=".setting" />
      <activity android:name=".dellAll" />
      <activity android:name=".reports" />
      <activity android:name=".login" />
  </application>

</manifest>

Answer 1

在 android API >= 23 中，您需要在运行时请求权限。看看here

类似的东西

        // Here, thisActivity is the current activity
    if (ContextCompat.checkSelfPermission(thisActivity,
            Manifest.permission.WRITE_EXTERNAL_STORAGE)
            != PackageManager.PERMISSION_GRANTED) {

        // Permission is not granted
        // Should we show an explanation?
        if (ActivityCompat.shouldShowRequestPermissionRationale(thisActivity,
                Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
            // Show an explanation 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; request the permission
            ActivityCompat.requestPermissions(thisActivity,
                    new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                    MY_PERMISSIONS_WRITE_EXTERNAL_STORAGE);

            // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
            // app-defined int constant. The callback method gets the
            // result of the request.
        }
    } else {
        // Permission has already been granted
    }

但是，Ted permission library 是一个很好的库，可以避免此类样板代码。

//call back after permission granted
    PermissionListener permissionlistener = new PermissionListener() {
        @Override
        public void onPermissionGranted() {
            Toast.makeText(MainActivity.this, "Permission Granted", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onPermissionDenied(List<String> deniedPermissions) {
            Toast.makeText(MainActivity.this, "Permission Denied\n" + deniedPermissions.toString(), Toast.LENGTH_SHORT).show();
        }


    };

    //check all needed permissions together
    TedPermission.with(this)
            .setPermissionListener(permissionlistener)
            .setDeniedMessage("If you reject permission,you can not use this service\n\nPlease turn on permissions at [Setting] > [Permission]")
            .setPermissions(Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE)
            .check();

Answer 2

推荐的解决方案： 使用 Dexter 或 KotlinPermissions 或 RxPermissions 等权限库。我都用过，很靠谱。

其他：

在您的活动中写下这些行，就在 super.onCreate(...) 下方和 setContentView(...) 之前：

super.onCreate(savedInstanceState);

    // Here, thisActivity is the current activity

    if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 1);
    }

    if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
    }

    if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, 1);
    }
    setContentView(R.layout.activity_main);

现在它应该可以工作了，它为我解决了问题！

Answer 3

从 android 24 及以上版本开始，您需要运行时权限才能访问设备的某些功能，例如麦克风和摄像头、存储等。使用以下代码检查您是否具有存储权限访问权限

  private boolean hasStoragePermission(int requestCode) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, requestCode);
            return false;
        } else {
            return true;
        }
    } else {
        return true;
    }
}

如果允许执行您的操作，它会显示允许访问的弹出窗口

 @Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    if (grantResults.length > 0
            && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        if (requestCode == FILE_ATTACHMENT)
            attachFile();

    }
}

Answer 4

ma​​rshmallow 或以上存储和图库使用的读写权限：

  private void requestPermission() {
      if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
          requestPermissions(new String[] {
              android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_WRITE_PERMISSION);
       } else {
           openFilePicker();
       }
  }

使用以下方法查看权限结果：

 @Override
 public void onRequestPermissionsResult(int requestCode, @NonNull String[] 
                                        permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);

    switch (requestCode) {
        case STORAGE_PERMISSION_REQUEST_CODE:
            if (grantResults.length > 0 && permissions[0].equals(Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
                // check whether storage permission granted or not.
                if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    // do what you want;
                }
            }
            break;
        default:
            break;
    }
}

Answer 5

清理该死的项目，如果仍然无法工作，则重新构建并运行....

将此代码添加到活动的 onCreate 方法中。删除应用程序，清理项目，构建并运行。也不要忘记在清单中添加您想要的权限。 （对于较低的 API 级别，代码是不必要的，但从 23 及以上您还需要此代码）

private fun requestPermission() {

    val permissions = arrayOf(Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.WRITE_EXTERNAL_STORAGE)
    this.requestPermissions(permissions, 5)
}