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Android example source code file (AppWidgetHost.java)

This example Android source code file (AppWidgetHost.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, appwidgethostview, appwidgetproviderinfo, arraylist, callbacks, content, handle_provider_changed, handle_update, hashmap, ibinder, message, object, os, remoteexception, remoteviews, runtimeexception, ui, updatehandler, util, widget

The AppWidgetHost.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.appwidget;

import android.content.Context;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.Message;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.widget.RemoteViews;

import java.util.ArrayList;
import java.util.HashMap;

import com.android.internal.appwidget.IAppWidgetHost;
import com.android.internal.appwidget.IAppWidgetService;

/**
 * AppWidgetHost provides the interaction with the AppWidget service for apps,
 * like the home screen, that want to embed AppWidgets in their UI.
 */
public class AppWidgetHost {

    static final int HANDLE_UPDATE = 1;
    static final int HANDLE_PROVIDER_CHANGED = 2;

    final static Object sServiceLock = new Object();
    static IAppWidgetService sService;

    Context mContext;
    String mPackageName;

    class Callbacks extends IAppWidgetHost.Stub {
        public void updateAppWidget(int appWidgetId, RemoteViews views) {
            Message msg = mHandler.obtainMessage(HANDLE_UPDATE);
            msg.arg1 = appWidgetId;
            msg.obj = views;
            msg.sendToTarget();
        }

        public void providerChanged(int appWidgetId, AppWidgetProviderInfo info) {
            Message msg = mHandler.obtainMessage(HANDLE_PROVIDER_CHANGED);
            msg.arg1 = appWidgetId;
            msg.obj = info;
            msg.sendToTarget();
        }
    }

    class UpdateHandler extends Handler {
        public UpdateHandler(Looper looper) {
            super(looper);
        }
        
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case HANDLE_UPDATE: {
                    updateAppWidgetView(msg.arg1, (RemoteViews)msg.obj);
                    break;
                }
                case HANDLE_PROVIDER_CHANGED: {
                    onProviderChanged(msg.arg1, (AppWidgetProviderInfo)msg.obj);
                    break;
                }
            }
        }
    }
    
    Handler mHandler;

    int mHostId;
    Callbacks mCallbacks = new Callbacks();
    final HashMap<Integer,AppWidgetHostView> mViews = new HashMap();

    public AppWidgetHost(Context context, int hostId) {
        mContext = context;
        mHostId = hostId;
        mHandler = new UpdateHandler(context.getMainLooper());
        synchronized (sServiceLock) {
            if (sService == null) {
                IBinder b = ServiceManager.getService(Context.APPWIDGET_SERVICE);
                sService = IAppWidgetService.Stub.asInterface(b);
            }
        }
    }

    /**
     * Start receiving onAppWidgetChanged calls for your AppWidgets.  Call this when your activity
     * becomes visible, i.e. from onStart() in your Activity.
     */
    public void startListening() {
        int[] updatedIds;
        ArrayList<RemoteViews> updatedViews = new ArrayList();
        
        try {
            if (mPackageName == null) {
                mPackageName = mContext.getPackageName();
            }
            updatedIds = sService.startListening(mCallbacks, mPackageName, mHostId, updatedViews);
        }
        catch (RemoteException e) {
            throw new RuntimeException("system server dead?", e);
        }

        final int N = updatedIds.length;
        for (int i=0; i<N; i++) {
            updateAppWidgetView(updatedIds[i], updatedViews.get(i));
        }
    }

    /**
     * Stop receiving onAppWidgetChanged calls for your AppWidgets.  Call this when your activity is
     * no longer visible, i.e. from onStop() in your Activity.
     */
    public void stopListening() {
        try {
            sService.stopListening(mHostId);
        }
        catch (RemoteException e) {
            throw new RuntimeException("system server dead?", e);
        }
    }

    /**
     * Get a appWidgetId for a host in the calling process.
     *
     * @return a appWidgetId
     */
    public int allocateAppWidgetId() {
        try {
            if (mPackageName == null) {
                mPackageName = mContext.getPackageName();
            }
            return sService.allocateAppWidgetId(mPackageName, mHostId);
        }
        catch (RemoteException e) {
            throw new RuntimeException("system server dead?", e);
        }
    }

    /**
     * Stop listening to changes for this AppWidget.  
     */
    public void deleteAppWidgetId(int appWidgetId) {
        synchronized (mViews) {
            mViews.remove(appWidgetId);
            try {
                sService.deleteAppWidgetId(appWidgetId);
            }
            catch (RemoteException e) {
                throw new RuntimeException("system server dead?", e);
            }
        }
    }

    /**
     * Remove all records about this host from the AppWidget manager.
     * <ul>
     *   <li>Call this when initializing your database, as it might be because of a data wipe.
     *   <li>Call this to have the AppWidget manager release all resources associated with your
     *   host.  Any future calls about this host will cause the records to be re-allocated.</li>
     * </ul>
     */
    public void deleteHost() {
        try {
            sService.deleteHost(mHostId);
        }
        catch (RemoteException e) {
            throw new RuntimeException("system server dead?", e);
        }
    }

    /**
     * Remove all records about all hosts for your package.
     * <ul>
     *   <li>Call this when initializing your database, as it might be because of a data wipe.
     *   <li>Call this to have the AppWidget manager release all resources associated with your
     *   host.  Any future calls about this host will cause the records to be re-allocated.</li>
     * </ul>
     */
    public static void deleteAllHosts() {
        try {
            sService.deleteAllHosts();
        }
        catch (RemoteException e) {
            throw new RuntimeException("system server dead?", e);
        }
    }

    public final AppWidgetHostView createView(Context context, int appWidgetId,
            AppWidgetProviderInfo appWidget) {
        AppWidgetHostView view = onCreateView(context, appWidgetId, appWidget);
        view.setAppWidget(appWidgetId, appWidget);
        synchronized (mViews) {
            mViews.put(appWidgetId, view);
        }
        RemoteViews views;
        try {
            views = sService.getAppWidgetViews(appWidgetId);
        } catch (RemoteException e) {
            throw new RuntimeException("system server dead?", e);
        }
        view.updateAppWidget(views);
        return view;
    }

    /**
     * Called to create the AppWidgetHostView.  Override to return a custom subclass if you
     * need it.  {@more}
     */
    protected AppWidgetHostView onCreateView(Context context, int appWidgetId,
            AppWidgetProviderInfo appWidget) {
        return new AppWidgetHostView(context);
    }
    
    /**
     * Called when the AppWidget provider for a AppWidget has been upgraded to a new apk.
     */
    protected void onProviderChanged(int appWidgetId, AppWidgetProviderInfo appWidget) {
        AppWidgetHostView v;
        synchronized (mViews) {
            v = mViews.get(appWidgetId);
        }
        if (v != null) {
            v.updateAppWidget(null, AppWidgetHostView.UPDATE_FLAGS_RESET);
        }
    }

    void updateAppWidgetView(int appWidgetId, RemoteViews views) {
        AppWidgetHostView v;
        synchronized (mViews) {
            v = mViews.get(appWidgetId);
        }
        if (v != null) {
            v.updateAppWidget(views, 0);
        }
    }
}


Other Android examples (source code examples)

Here is a short list of links related to this Android AppWidgetHost.java source code file:

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