src/com/android/browser/PermissionsActivity.java

package com.android.browser;

import android.Manifest;
import android.app.Activity;
import android.app.Dialog;
import android.app.AlertDialog;
import android.app.KeyguardManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.content.pm.PackageManager;
import android.preference.PreferenceManager;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Window;
import android.view.WindowManager;
import com.android.browser.R;

/**
 * Activity that shows permissions request dialogs and handles lack of critical permissions.
 */
public class PermissionsActivity extends Activity {
    private static final String TAG = "PermissionsActivity";

    private static String PREF_HAS_SEEN_PERMISSIONS_DIALOGS = "pref_has_seen_permissions_dialogs";
    private static int PERMISSION_REQUEST_CODE = 1;
    private static int RESULT_CODE_OK = 1;
    private static int RESULT_CODE_FAILED = 2;

    private int mIndexPermissionRequestStorage;
    private boolean mShouldRequestStoragePermission;
    private int mNumPermissionsToRequest;
    private boolean mFlagHasStoragePermission;
    private SharedPreferences mPrefs;

    /**
     * Close activity when secure app passes lock screen or screen turns
     * off.
     */
    private final BroadcastReceiver mShutdownReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            Log.v(TAG, "received intent, finishing: " + intent.getAction());
            finish();
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mPrefs = PreferenceManager.getDefaultSharedPreferences(this);
    }

    @Override
    protected void onResume() {
        super.onResume();
        mNumPermissionsToRequest = 0;
        checkPermissions();
    }

    private void checkPermissions() {
        if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE)
                != PackageManager.PERMISSION_GRANTED) {
            mNumPermissionsToRequest++;
            mShouldRequestStoragePermission = true;
        } else {
            mFlagHasStoragePermission = true;
        }

        if (mNumPermissionsToRequest != 0) {
            if (!mPrefs.getBoolean(PREF_HAS_SEEN_PERMISSIONS_DIALOGS, false)) {
                buildPermissionsRequest();
            } else {
                // Permissions dialog has already been shown
                // and we're still missing permissions.
                handlePermissionsFailure();
            }
        } else {
            handlePermissionsSuccess();
        }
    }

    private void buildPermissionsRequest() {
        String[] permissionsToRequest = new String[mNumPermissionsToRequest];
        int permissionsRequestIndex = 0;

        if (mShouldRequestStoragePermission) {
            permissionsToRequest[permissionsRequestIndex] = Manifest.permission.READ_EXTERNAL_STORAGE;
            mIndexPermissionRequestStorage = permissionsRequestIndex;
            permissionsRequestIndex++;
        }

        Log.v(TAG, "requestPermissions count: " + permissionsToRequest.length);
        requestPermissions(permissionsToRequest, PERMISSION_REQUEST_CODE);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String permissions[],
            int[] grantResults) {
        Log.v(TAG, "onPermissionsResult counts: " + permissions.length + ":" + grantResults.length);

        if (mShouldRequestStoragePermission) {
            if (grantResults.length > 0 && grantResults[mIndexPermissionRequestStorage] ==
                    PackageManager.PERMISSION_GRANTED) {
                mFlagHasStoragePermission = true;
            } else {
                handlePermissionsFailure();
            }
        }

        if (mFlagHasStoragePermission) {
            handlePermissionsSuccess();
        }
    }

    private void handlePermissionsSuccess() {
        Editor edit = mPrefs.edit();
        edit.putBoolean(PREF_HAS_SEEN_PERMISSIONS_DIALOGS, true);
        edit.commit();

        Intent intent = new Intent(this, BrowserActivity.class);
        startActivity(intent);
        finish();
    }

    private void handlePermissionsFailure() {
        new AlertDialog.Builder(this).setTitle(getResources().getString(R.string.browser_error_title))
                .setMessage(getResources().getString(R.string.error_permissions))
                .setPositiveButton(getResources().getString(R.string.dialog_dismiss),
                        new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        finish();
                    }
                })
                .show();
    }
}