Android studio 请求用户访问未显示的文件的权限

我试图使一个应用程序，用户可以选择一个个人资料图片。单击图片时，会弹出一条消息，要求获得访问设备文件的权限。我运行了代码并按下了“拒绝”，现在“请求权限”窗口不再出现

public class profileClass extends AppCompatActivity {

    CircleImageView regUserPhoto;
    static int PReqCode = 1;
    static int REQUESTCODE = 1;
    Uri pickedImage;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.profile_activity);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.profile_activity);

        regUserPhoto = findViewById(R.id.regUserPhoto);

        regUserPhoto.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(Build.VERSION.SDK_INT >= 22){
                    checkAndRequestForPermission();
                }else{
                    openGallery();
                }
            }




        });

    }
    private void openGallery() {
        Intent galleryIntent = new Intent(Intent.ACTION_GET_CONTENT);
        galleryIntent.setType("image/*");
        startActivityForResult(galleryIntent,REQUESTCODE);

    }


    private void checkAndRequestForPermission() {
        if(ContextCompat.checkSelfPermission(profileClass.this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){
            if (ActivityCompat.shouldShowRequestPermissionRationale(profileClass.this, Manifest.permission.READ_EXTERNAL_STORAGE)){
                Toast.makeText(profileClass.this,"Please Accept for required permission",Toast.LENGTH_SHORT).show();
            }else{
                ActivityCompat.requestPermissions((profileClass.this),new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},PReqCode);
            }
        }else{
            openGallery();
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data){
        super.onActivityResult(requestCode,resultCode,data);

        if(resultCode == RESULT_OK && requestCode == REQUESTCODE && data != null ){
            pickedImage = data.getData();
            regUserPhoto.setImageURI(pickedImage);
        }
    }
}

---

我也有同样的问题，我也解决了。为了简化操作，我编写了一个util类来处理运行时权限

public class PermissionUtil {
    /*
    * Check if version is marshmallow and above.
    * Used in deciding to ask runtime permission
    * */
    public static boolean shouldAskPermission() {
        return (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M);
    }
private static boolean shouldAskPermission(Context context, String permission){
        if (shouldAskPermission()) {
            int permissionResult = ActivityCompat.checkSelfPermission(context, permission);
            if (permissionResult != PackageManager.PERMISSION_GRANTED) {
                return true;
            }
        }
        return false;
    }
public static void checkPermission(Context context, String permission, PermissionAskListener listener){
/*
        * If permission is not granted
        * */
        if (shouldAskPermission(context, permission)){
/*
            * If permission denied previously
            * */
            if (((Activity) context).shouldShowRequestPermissionRationale(permission)) {
                listener.onPermissionPreviouslyDenied();
            } else {
                /*
                * Permission denied or first time requested
                * */
if (PreferencesUtil.isFirstTimeAskingPermission(context, permission)) {
                    PreferencesUtil.firstTimeAskingPermission(context, permission, false);
                    listener.onPermissionAsk();
                } else {
                    /*
                    * Handle the feature without permission or ask user to manually allow permission
                    * */
                    listener.onPermissionDisabled();
                }
            }
        } else {
            listener.onPermissionGranted();
        }
    }
/*
    * Callback on various cases on checking permission
    *
    * 1.  Below M, runtime permission not needed. In that case onPermissionGranted() would be called.
    *     If permission is already granted, onPermissionGranted() would be called.
    *
    * 2.  Above M, if the permission is being asked first time onPermissionAsk() would be called.
    *
    * 3.  Above M, if the permission is previously asked but not granted, onPermissionPreviouslyDenied()
    *     would be called.
    *
    * 4.  Above M, if the permission is disabled by device policy or the user checked "Never ask again"
    *     check box on previous request permission, onPermissionDisabled() would be called.
    * */
    public interface PermissionAskListener {
/*
        * Callback to ask permission
        * */
        void onPermissionAsk();
/*
        * Callback on permission denied
        * */
        void onPermissionPreviouslyDenied();
/*
        * Callback on permission "Never show again" checked and denied
        * */
        void onPermissionDisabled();
/*
        * Callback on permission granted
        * */
        void onPermissionGranted();
    }
}

PreferenceUtil方法如下所示

public static void firstTimeAskingPermission(Context context, String permission, boolean isFirstTime){
SharedPreferences sharedPreference = context.getSharedPreferences(PREFS_FILE_NAME, MODE_PRIVATE;
 sharedPreference.edit().putBoolean(permission, isFirstTime).apply();
 }
public static boolean isFirstTimeAskingPermission(Context context, String permission){
return context.getSharedPreferences(PREFS_FILE_NAME, MODE_PRIVATE).getBoolean(permission, true);
}

现在，您只需要使用带有适当参数的checkPermission方法

举个例子,

PermissionUtil.checkPermission(context, Manifest.permission.WRITE_EXTERNAL_STORAGE,
                    new PermissionUtil.PermissionAskListener() {
                        @Override
                        public void onPermissionAsk() {
                            ActivityCompat.requestPermissions(
                                    thisActivity,
              new String[]{Manifest.permission.READ_CONTACTS},
                            REQUEST_EXTERNAL_STORAGE
                            );
                        }
@Override
                        public void onPermissionPreviouslyDenied() {
                       //show a dialog explaining permission and then request permission
                        }
@Override
                        public void onPermissionDisabled() {
Toast.makeText(context, "Permission Disabled.", Toast.LENGTH_SHORT).show();
                        }
@Override
                        public void onPermissionGranted() {
                            readContacts();
                        }
                    });

案例1：应用程序没有权限，并且用户尚未访问 我以前请求过许可。在这种情况下,， shouldShowRequestPermissionRegulation（）将返回false，因为 这是我们第一次询问用户

案例2：用户拒绝了权限并选择了“不询问” 同样”，在这种情况下，也应该显示RequestPermissionRegulation（）将 返回false

在案例2中，我想将用户发送到应用程序的设置页面。 我如何区分这两种情况

对于案例1，您将收到onPermissionAsk的回调，对于案例2，您将收到onPermissionDisabled的回调

快乐编码：）