Android example source code file (GeolocationPermissions.java)

This example Android source code file (GeolocationPermissions.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, boolean, clear, geolocationpermissions, get_allowed, get_origins, handler, hashmap, map, object, os, return_allowed, return_origins, set, string, util, utilities, utils, valuecallback

The GeolocationPermissions.java Android example source code

/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * 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 android.webkit;

import android.os.Handler;
import android.os.Message;
import android.util.Log;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.Vector;


/**
 * This class is used to get Geolocation permissions from, and set them on the
 * WebView. For example, it could be used to allow a user to manage Geolocation
 * permissions from a browser's UI.
 *
 * Permissions are managed on a per-origin basis, as required by the
 * Geolocation spec - http://dev.w3.org/geo/api/spec-source.html. An origin
 * specifies the scheme, host and port of particular frame. An origin is
 * represented here as a string, using the output of
 * WebCore::SecurityOrigin::toString.
 *
 * This class is the Java counterpart of the WebKit C++ GeolocationPermissions
 * class. It simply marshalls calls from the UI thread to the WebKit thread.
 *
 * Within WebKit, Geolocation permissions may be applied either temporarily
 * (for the duration of the page) or permanently. This class deals only with
 * permanent permissions.
 */
public final class GeolocationPermissions {
    /**
     * Callback interface used by the browser to report a Geolocation permission
     * state set by the user in response to a permissions prompt.
     */
    public interface Callback {
        public void invoke(String origin, boolean allow, boolean remember);
    };

    // Log tag
    private static final String TAG = "geolocationPermissions";

    // Global instance
    private static GeolocationPermissions sInstance;

    private Handler mHandler;
    private Handler mUIHandler;

    // A queue to store messages until the handler is ready.
    private Vector<Message> mQueuedMessages;

    // Message ids
    static final int GET_ORIGINS = 0;
    static final int GET_ALLOWED = 1;
    static final int CLEAR = 2;
    static final int ALLOW = 3;
    static final int CLEAR_ALL = 4;

    // Message ids on the UI thread
    static final int RETURN_ORIGINS = 0;
    static final int RETURN_ALLOWED = 1;

    private static final String ORIGINS = "origins";
    private static final String ORIGIN = "origin";
    private static final String CALLBACK = "callback";
    private static final String ALLOWED = "allowed";

    /**
     * Gets the singleton instance of the class.
     */
    public static GeolocationPermissions getInstance() {
      if (sInstance == null) {
          sInstance = new GeolocationPermissions();
      }
      return sInstance;
    }

    /**
     * Creates the UI message handler. Must be called on the UI thread.
     * @hide
     */
    public void createUIHandler() {
        if (mUIHandler == null) {
            mUIHandler = new Handler() {
                @Override
                public void handleMessage(Message msg) {
                    // Runs on the UI thread.
                    switch (msg.what) {
                        case RETURN_ORIGINS: {
                            Map values = (Map) msg.obj;
                            Set<String> origins = (Set) values.get(ORIGINS);
                            ValueCallback<Set callback = (ValueCallback >) values.get(CALLBACK);
                            callback.onReceiveValue(origins);
                        } break;
                        case RETURN_ALLOWED: {
                            Map values = (Map) msg.obj;
                            Boolean allowed = (Boolean) values.get(ALLOWED);
                            ValueCallback<Boolean> callback = (ValueCallback) values.get(CALLBACK);
                            callback.onReceiveValue(allowed);
                        } break;
                    }
                }
            };
        }
    }

    /**
     * Creates the message handler. Must be called on the WebKit thread.
     * @hide
     */
    public synchronized void createHandler() {
        if (mHandler == null) {
            mHandler = new Handler() {
                @Override
                public void handleMessage(Message msg) {
                    // Runs on the WebKit thread.
                    switch (msg.what) {
                        case GET_ORIGINS: {
                            Set origins = nativeGetOrigins();
                            ValueCallback callback = (ValueCallback) msg.obj;
                            Map values = new HashMap<String, Object>();
                            values.put(CALLBACK, callback);
                            values.put(ORIGINS, origins);
                            postUIMessage(Message.obtain(null, RETURN_ORIGINS, values));
                            } break;
                        case GET_ALLOWED: {
                            Map values = (Map) msg.obj;
                            String origin = (String) values.get(ORIGIN);
                            ValueCallback callback = (ValueCallback) values.get(CALLBACK);
                            boolean allowed = nativeGetAllowed(origin);
                            Map retValues = new HashMap<String, Object>();
                            retValues.put(CALLBACK, callback);
                            retValues.put(ALLOWED, new Boolean(allowed));
                            postUIMessage(Message.obtain(null, RETURN_ALLOWED, retValues));
                            } break;
                        case CLEAR:
                            nativeClear((String) msg.obj);
                            break;
                        case ALLOW:
                            nativeAllow((String) msg.obj);
                            break;
                        case CLEAR_ALL:
                            nativeClearAll();
                            break;
                    }
                }
            };

            // Handle the queued messages
            if (mQueuedMessages != null) {
                while (!mQueuedMessages.isEmpty()) {
                    mHandler.sendMessage(mQueuedMessages.remove(0));
                }
                mQueuedMessages = null;
            }
        }
    }

    /**
     * Utility function to send a message to our handler.
     */
    private synchronized void postMessage(Message msg) {
        if (mHandler == null) {
            if (mQueuedMessages == null) {
                mQueuedMessages = new Vector<Message>();
            }
            mQueuedMessages.add(msg);
        } else {
            mHandler.sendMessage(msg);
        }
    }

    /**
     * Utility function to send a message to the handler on the UI thread
     */
    private void postUIMessage(Message msg) {
        if (mUIHandler != null) {
            mUIHandler.sendMessage(msg);
        }
    }

    /**
     * Gets the set of origins for which Geolocation permissions are stored.
     * Note that we represent the origins as strings. These are created using
     * WebCore::SecurityOrigin::toString(). As long as all 'HTML 5 modules'
     * (Database, Geolocation etc) do so, it's safe to match up origins based
     * on this string.
     *
     * Callback is a ValueCallback object whose onReceiveValue method will be
     * called asynchronously with the set of origins.
     */
    public void getOrigins(ValueCallback<Set callback) {
        if (callback != null) {
            if (WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName())) {
                Set origins = nativeGetOrigins();
                callback.onReceiveValue(origins);
            } else {
                postMessage(Message.obtain(null, GET_ORIGINS, callback));
            }
        }
    }

    /**
     * Gets the permission state for the specified origin.
     *
     * Callback is a ValueCallback object whose onReceiveValue method will be
     * called asynchronously with the permission state for the origin.
     */
    public void getAllowed(String origin, ValueCallback<Boolean> callback) {
        if (callback == null) {
            return;
        }
        if (origin == null) {
            callback.onReceiveValue(null);
            return;
        }
        if (WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName())) {
            boolean allowed = nativeGetAllowed(origin);
            callback.onReceiveValue(new Boolean(allowed));
        } else {
            Map values = new HashMap<String, Object>();
            values.put(ORIGIN, origin);
            values.put(CALLBACK, callback);
            postMessage(Message.obtain(null, GET_ALLOWED, values));
        }
    }

    /**
     * Clears the permission state for the specified origin. This method may be
     * called before the WebKit thread has intialized the message handler.
     * Messages will be queued until this time.
     */
    public void clear(String origin) {
        // Called on the UI thread.
        postMessage(Message.obtain(null, CLEAR, origin));
    }

    /**
     * Allows the specified origin. This method may be called before the WebKit
     * thread has intialized the message handler. Messages will be queued until
     * this time.
     */
    public void allow(String origin) {
        // Called on the UI thread.
        postMessage(Message.obtain(null, ALLOW, origin));
    }

    /**
     * Clears the permission state for all origins.
     */
    public void clearAll() {
        // Called on the UI thread.
        postMessage(Message.obtain(null, CLEAR_ALL));
    }

    // Native functions, run on the WebKit thread.
    private static native Set nativeGetOrigins();
    private static native boolean nativeGetAllowed(String origin);
    private static native void nativeClear(String origin);
    private static native void nativeAllow(String origin);
    private static native void nativeClearAll();
}