Android - 在启动时提示/请求权限

Question

我正在尝试获取一个弹出窗口，请求用户在启动期间授予访问外部存储的权限。我有一个名为 Start 的活动，这是我的 Launcher 活动。通过此活动，我声明了一些全局变量并创建了一些目录（如果不存在）。为此，我需要对外部存储的权限。我已经实现了在 developer.android.com 上共享的代码，但它没有授予我所需的权限。

我认为这不起作用，因为请求用户输入的弹出窗口没有显示，因为 layout.activity_wait 还不可见，因此我应该将我的代码分发到 AsyncTask 中，以便 layout.activity_wait 在调用 requestPermissions 之前可见。

下面的代码没有 AsyncTask（是的，我知道应用程序也应该能够在没有权限的情况下工作，我将在稍后阶段构建它:)）。请让我知道您对此有何看法。谢谢！

public class Start extends AppCompatActivity {

    /**
    set a bunch of variables to be used in all activities
    **/

    public static ...
    public static ... ...
    public static int MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE = 0;



    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_wait);

        checkPermission();


        /**
        do some stuff at startup, like creating some directories if not already present
        **/

        launchIntent(this, Home.class); //launch the home screen after initializing all variables and creating directories
        finish();
    }


    private void checkPermission() {
        if (ContextCompat.checkSelfPermission(Start.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
                != PackageManager.PERMISSION_GRANTED) {
            Log.d("permission", "NOT granted");
             ActivityCompat.requestPermissions(Start.this,
                        new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                        MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE);
        }else{
            Log.d("permission", "granted");
        }
    }
}

Answer 1

感谢@Mike M. 设法让它工作。我不明白 onRequestPermissionsResult() 的目的。现在我愿意。请参阅下面的代码。

public class Start extends AppCompatActivity implements ActivityCompat.OnRequestPermissionsResultCallback {

        /**
        set a bunch of variables to be used in all activities
        **/

        public static ...
        public static ... ...
        public static int MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE = 0;



        public void onCreate(Bundle savedInstanceState) {

            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_wait); //this is a view with a progress bar
            checkPermission();

        }

        private void permissionsGranted() {

                 /**
            do some stuff at startup, like creating some directories if not already present
            **/

            launchIntent(this, Home.class); //launch the home screen after initializing all variables and creating directories
            finish();


        }



        private void checkPermission() {
            if (ContextCompat.checkSelfPermission(Start.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                // do this if permisisons have not yet been granted
                Log.d("permission", "NOT granted");
                ActivityCompat.requestPermissions(Start.this,
                        new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                        MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE);
            }else{
                // if the permissions have already been granted do the following
                Log.d("permission", "granted");
                permissionsGranted();
            }
        }

        // this is required when ActivityCompat.requestPermissions() is called
        @Override
        public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
            switch (requestCode) {
                case MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE: {

                    if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                       // if permissions have been granted, do the following 
                        permissionsGranted();
                    } else {
                        // possibly prompt why permissions are required and try again
                    }
                    return;
                }

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

    }