android - 读取和写入外部存储权限不起作用

Question

在我的应用程序中，我想获得用户权限以在外部存储上读取和写入数据，我已将权限标记放在我的 list 中，如下所示。但是当安装应用程序或运行时以及需要读取或写入存储的地方时，没有从用户那里获得许可并且读取和写入内存是行不通的，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 list 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

像这样

        // 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
    }

然而，Ted permission library是避免此类样板代码的好库。

//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();