Add permission request

app/src/main/java/com/hippo/ehviewer/ui/MainActivity.java

@@ -16,10 +16,13 @@
 
 package com.hippo.ehviewer.ui;
 
+import android.Manifest;
 import android.content.Intent;
+import android.content.pm.PackageManager;
 import android.os.Bundle;
 import android.os.PersistableBundle;
 import android.support.annotation.IdRes;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.design.widget.NavigationView;
 import android.support.v4.widget.DrawerLayout;
@@ -37,10 +40,13 @@ import com.hippo.ehviewer.ui.scene.WarningScene;
 import com.hippo.scene.Announcer;
 import com.hippo.scene.SceneFragment;
 import com.hippo.scene.StageActivity;
+import com.hippo.util.PermissionRequester;
 
 public final class MainActivity extends StageActivity
         implements NavigationView.OnNavigationItemSelectedListener {
 
+    private static final int PERMISSION_REQUEST_WRITE_EXTERNAL_STORAGE = 0;
+
     private static final String KEY_NAV_CHECKED_ITEM = "nav_checked_item";
 
     private DrawerLayout mDrawerLayout;
@@ -96,6 +102,7 @@ public final class MainActivity extends StageActivity
             if (intent != null && Intent.ACTION_VIEW.equals(intent.getAction())) {
                 Toast.makeText(this, R.string.error_cannot_parse_the_url, Toast.LENGTH_SHORT).show();
                 finish();
+                return;
             } else {
                 if (Settings.getShowWarning()) {
                     setDrawerLayoutEnable(false);
@@ -111,6 +118,10 @@ public final class MainActivity extends StageActivity
                 }
             }
         }
+
+        // Check permission
+        PermissionRequester.request(this, Manifest.permission.WRITE_EXTERNAL_STORAGE,
+                getString(R.string.write_rationale), PERMISSION_REQUEST_WRITE_EXTERNAL_STORAGE);
     }
 
     private void onRestore(Bundle savedInstanceState) {
@@ -130,6 +141,18 @@ public final class MainActivity extends StageActivity
         setNavCheckedItem(mNavCheckedItem);
     }
 
+    @Override
+    public void onRequestPermissionsResult(int requestCode,
+            @NonNull String[] permissions, @NonNull int[] grantResults) {
+        if (requestCode == PERMISSION_REQUEST_WRITE_EXTERNAL_STORAGE) {
+            if (grantResults.length == 1 && grantResults[0] != PackageManager.PERMISSION_GRANTED) {
+                Toast.makeText(this, R.string.you_rejected_me, Toast.LENGTH_SHORT).show();
+            }
+        } else {
+            super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+        }
+    }
+
     public void setDrawerLayoutEnable(boolean enable) {
         if (enable) {
             mDrawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED);

app/src/main/java/com/hippo/util/PermissionRequester.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2015 Hippo Seven
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hippo.util;
+
+import android.app.Activity;
+import android.content.DialogInterface;
+import android.content.pm.PackageManager;
+import android.support.v4.app.ActivityCompat;
+import android.support.v7.app.AlertDialog;
+
+public class PermissionRequester {
+
+    /**
+     * @return true for there no need to request, do your work it now.
+     * false for do in {@link android.support.v4.app.ActivityCompat.OnRequestPermissionsResultCallback#onRequestPermissionsResult(int, String[], int[])}
+     */
+    public static boolean request(final Activity activity, final String permission, String rationale, final int requestCode) {
+        if (!(activity instanceof ActivityCompat.OnRequestPermissionsResultCallback)) {
+            throw new IllegalStateException("The Activity must implement ActivityCompat.OnRequestPermissionsResultCallback");
+        }
+
+        if (ActivityCompat.checkSelfPermission(activity, permission)
+                == PackageManager.PERMISSION_GRANTED) {
+            return true;
+        }
+
+        if (ActivityCompat.shouldShowRequestPermissionRationale(activity, permission)) {
+            new AlertDialog.Builder(activity)
+                    .setMessage(rationale)
+                    .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                        @Override
+                        public void onClick(DialogInterface dialog, int which) {
+                            ActivityCompat.requestPermissions(activity,
+                                    new String[]{permission},
+                                    requestCode);
+                        }
+                    }).setNegativeButton(android.R.string.cancel, null);
+        } else {
+            ActivityCompat.requestPermissions(activity,
+                    new String[]{permission},
+                    requestCode);
+        }
+
+        return false;
+    }
+}