Implementing geolocation for the Android Webview

android_webview/java/src/org/chromium/android_webview/AwGeolocationPermissions.java

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.android_webview;
 
 import android.content.SharedPreferences;
 import android.webkit.ValueCallback;
 
 import org.chromium.base.ThreadUtils;
 import org.chromium.net.GURLUtils;
 
 import java.util.HashSet;
 import java.util.Set;
 
 /**
  * This class is used to manage permissions for the WebView's Geolocation JavaScript API.
  *
  * Callbacks are posted on the UI thread.
  */
 public final class AwGeolocationPermissions {
 
     private static final String PREF_PREFIX =
             AwGeolocationPermissions.class.getCanonicalName() + "%";
     private final SharedPreferences mSharedPreferences;
 
+    private static AwGeolocationPermissions sInstance;
+
+    // TODO(kristianm): Rewrite when AwBrowserContext has landed in
+    // CL: https://codereview.chromium.org/12208099/
     public AwGeolocationPermissions(SharedPreferences sharedPreferences) {
         mSharedPreferences = sharedPreferences;
+        setInstance(this);
     }
 
+    private static void setInstance(AwGeolocationPermissions instance) {
+        synchronized (AwGeolocationPermissions.class) {
+            sInstance = instance;
+        }
+    }
+
+    /**
+     * Get the static instance after it has been created
+     */
+    public static AwGeolocationPermissions getInstance() {
+        synchronized (AwGeolocationPermissions.class) {
+            if (sInstance == null) {
+                throw new IllegalStateException("This should only be called after createInstance.");
+            }
+        }
+        return sInstance;
+    }
+
+    /**
+     * Create the static instance of this class
+     */
+    public static AwGeolocationPermissions createInstance(
+            SharedPreferences sharedPreferences) {
+        synchronized (AwGeolocationPermissions.class) {
+            if (sInstance != null) {
+                throw new IllegalStateException("This should only be called once.");
+            }
+            // sInstance set in the constructor
+            new AwGeolocationPermissions(sharedPreferences);
+            return sInstance;
+        }
+    }
+
+    /**
+     * Set one origin to be allowed.
+     */
     public void allow(String origin) {
         String key = getOriginKey(origin);
         if (key != null) {
             mSharedPreferences.edit().putBoolean(key, true).apply();
         }
     }
 
+    /**
+     * Set one origin to be denied.
+     */
     public void deny(String origin) {
         String key = getOriginKey(origin);
         if (key != null) {
             mSharedPreferences.edit().putBoolean(key, false).apply();
         }
     }
 
+    /**
+     * Clear the stored permission for a particular origin.
+     */
     public void clear(String origin) {
         String key = getOriginKey(origin);
         if (key != null) {
             mSharedPreferences.edit().remove(key).apply();
         }
     }
 
+    /**
+     * Clear stored permissions for all origins.
+     */
     public void clearAll() {
         SharedPreferences.Editor editor = null;
         for (String name : mSharedPreferences.getAll().keySet()) {
             if (name.startsWith(PREF_PREFIX)) {
                 if (editor == null) {
                     editor = mSharedPreferences.edit();
                 }
                 editor.remove(name);
             }
         }
         if (editor != null) {
             editor.apply();
         }
     }
 
+    /**
+     * Synchronous method to get if an origin is set to be allowed.
+     */
+    public boolean isOriginAllowed(String origin) {
+        return mSharedPreferences.getBoolean(getOriginKey(origin), false);
+    }
+
+    /**
+     * Returns true if the origin is either set to allowed or denied.
+     */
+    public boolean hasOrigin(String origin) {
+        return mSharedPreferences.contains(getOriginKey(origin));
+    }
+
+    /**
+     * Asynchronous method to get if an origin set to be allowed.
+     */
     public void getAllowed(String origin, final ValueCallback<Boolean> callback) {
-        boolean allowed = false;
-        try {
-            String key = getOriginKey(origin);
-            if (key != null) {
-                allowed = mSharedPreferences.getBoolean(key, false);
-            }
-        } catch (ClassCastException e) {
-            // Want to return false in this case, do nothing here
-        }
-        final boolean finalAllowed = allowed;
+        final boolean finalAllowed = isOriginAllowed(origin);
         ThreadUtils.postOnUiThread(new Runnable() {
             @Override
             public void run() {
                 callback.onReceiveValue(finalAllowed);
             }
         });
     }
 
+    /**
+     * Async method to get the domains currently allowed or denied.
+     */
     public void getOrigins(final ValueCallback<Set<String>> callback) {
         final Set<String> origins = new HashSet<String>();
         for (String name : mSharedPreferences.getAll().keySet()) {
             if (name.startsWith(PREF_PREFIX)) {
                 origins.add(name.substring(PREF_PREFIX.length()));
             }
         }
         ThreadUtils.postOnUiThread(new Runnable() {
             @Override
             public void run() {
                 callback.onReceiveValue(origins);
             }
         });
     }
 
+    /**
+     * Get the domain of an URL using the GURL library.
+     */
     private String getOriginKey(String url) {
         String origin = GURLUtils.getOrigin(url);
         if (origin.isEmpty()) {
             return null;
         }
 
         return PREF_PREFIX + origin;
     }
 }