src/com/android/gallery3d/app/AbstractPermissionActivity.java

/*
 * Copyright (c) 2016, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials provided
 *    with the distribution.
 *  * Neither the name of The Linux Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.android.gallery3d.app;

import android.Manifest;
import android.app.Activity;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;

import java.util.ArrayList;

public abstract class AbstractPermissionActivity extends FragmentActivity {

    public static final int PERMISSION_REQUEST_STORAGE = 1;
    private boolean permissionGranted = false;

    protected abstract void onGetPermissionsSuccess();
    protected abstract void onGetPermissionsFailure();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestStoragePermission();
    }

    private void requestStoragePermission() {
        String[] permissions = {
                Manifest.permission.WRITE_EXTERNAL_STORAGE,
                Manifest.permission.READ_EXTERNAL_STORAGE
        };
        requestPermission(permissions, PERMISSION_REQUEST_STORAGE);
    }

    protected void requestPermission(String[] permissions, int requestCode) {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            permissionGranted = true;
            return;
        }

        boolean needRequest = false;
        ArrayList<String> permissionList = new ArrayList<String>();
        for (String permission : permissions) {
            if (checkSelfPermission(permission) != PackageManager.PERMISSION_GRANTED) {
                permissionList.add(permission);
                needRequest = true;
            }
        }

        if (needRequest) {
            int count = permissionList.size();
            if (count > 0) {
                String[] permissionArray = new String[count];
                for (int i = 0; i < count; i++) {
                    permissionArray[i] = permissionList.get(i);
                }

                requestPermissions(permissionArray, requestCode);
            }
        }
        permissionGranted = !needRequest;
    }

    private boolean checkPermissionGrantResults(int[] grantResults) {
        for (int result : grantResults) {
            if (result != PackageManager.PERMISSION_GRANTED) {
                return false;
            }
        }
        return true;
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions,
                                           int[] grantResults) {
        permissionGranted = checkPermissionGrantResults(grantResults);
        switch (requestCode) {
            case PERMISSION_REQUEST_STORAGE: {
                if (permissionGranted) {
                    onGetPermissionsSuccess();
                } else {
                    onGetPermissionsFailure();
                }
            }
        }
    }

    protected boolean isPermissionGranted() {
        return permissionGranted;
    }
}