Android 3.0自带的天气预报例子代码

Android 3.0正式版API Level 11中加入了一个天气预报例子，下面是manifest.xml中的关键代码，只是少了xml的编码头:

  <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.android.weatherlistwidget">
    <uses-sdk android:minSdkVersion="11" />
    <application android:label="Weather Widget Sample">
         <receiver android:name="WeatherWidgetProvider">
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
            </intent-filter>
                   <meta-data android:name="android.appwidget.provider"
                    android:resource="@xml/widgetinfo" />
        </receiver>

         <service android:name="WeatherWidgetService"
            android:permission="android.permission.BIND_REMOTEVIEWS"
            android:exported="false" />

         <provider android:name="WeatherDataProvider"
              android:authorities="com.example.android.weatherlistwidget.provider" />
    </application>
</manifest>

这里WeatherDataProvider.java的源码为主要是ContentProvider相关的处理，这里作为appWidget的receiver

  class WeatherDataPoint {
    String city; //城市
    int degrees; //度数

    WeatherDataPoint(String c, int d) {
        city = c;
        degrees = d;
    }
}

public class WeatherDataProvider extends ContentProvider {
    public static final Uri CONTENT_URI =
        Uri.parse("content://com.example.android.weatherlistwidget.provider");
    public static class Columns {
        public static final String ID = "_id";
        public static final String CITY = "city";
        public static final String TEMPERATURE = "temperature";
    }

     private static final ArrayList<WeatherDataPoint> sData = new ArrayList<WeatherDataPoint>();

    @Override
    public boolean onCreate() {
        sData.add(new WeatherDataPoint("San Francisco", 13));
        sData.add(new WeatherDataPoint("New York", 1));
        sData.add(new WeatherDataPoint("Seattle", 7));
        sData.add(new WeatherDataPoint("Boston", 4));
        sData.add(new WeatherDataPoint("Miami", 22));
        sData.add(new WeatherDataPoint("Toronto", -10));
        sData.add(new WeatherDataPoint("Calgary", -13));
        sData.add(new WeatherDataPoint("Tokyo",);
        sData.add(new WeatherDataPoint("Kyoto", 11));
        sData.add(new WeatherDataPoint("London", -1));
        sData.add(new WeatherDataPoint("Nomanisan", 27));
        return true;
    }

    @Override
    public synchronized Cursor query(Uri uri, String[] projection, String selection,
            String[] selectionArgs, String sortOrder) {
        assert(uri.getPathSegments().isEmpty());

         final MatrixCursor c = new MatrixCursor(
                new String[]{ Columns.ID, Columns.CITY, Columns.TEMPERATURE });
        for (int i = 0; i < sData.size(); ++i) {
            final WeatherDataPoint data = sData.get(i);
            c.addRow(new Object[]{ new Integer(i), data.city, new Integer(data.degrees) });
        }
        return c;
    }

    @Override
    public String getType(Uri uri) {
        return "vnd.android.cursor.dir/vnd.weatherlistwidget.citytemperature";
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        return null;
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        return 0;
    }

    @Override
    public synchronized int update(Uri uri, ContentValues values, String selection,
            String[] selectionArgs) {
        assert(uri.getPathSegments().size() == 1);

        final int index = Integer.parseInt(uri.getPathSegments().get(0));
        final MatrixCursor c = new MatrixCursor(
                new String[]{ Columns.ID, Columns.CITY, Columns.TEMPERATURE });
        assert(0 <= index && index < sData.size());
        final WeatherDataPoint data = sData.get(index);
        data.degrees = values.getAsInteger(Columns.TEMPERATURE);

         getContext().getContentResolver().notifyChange(uri, null);
        return 1;
    }

}

上面可以看到，对于插入和删除没有做过多的处理，对于天气更新给出了详细的解决方法。

有关 WeatherWidgetProvider.java 主要是appWidget的核心，为provider

class WeatherDataProviderObserver extends ContentObserver { //监控数据库的变化
    private AppWidgetManager mAppWidgetManager;
    private ComponentName mComponentName;

    WeatherDataProviderObserver(AppWidgetManager mgr, ComponentName cn, Handler h) {
        super(h);
        mAppWidgetManager = mgr;
        mComponentName = cn;
    }

    @Override
    public void onChange(boolean selfChange) {
           mAppWidgetManager.notifyAppWidgetViewDataChanged(
                mAppWidgetManager.getAppWidgetIds(mComponentName), R.id.weather_list);
    }
}

public class WeatherWidgetProvider extends AppWidgetProvider {
    public static String CLICK_ACTION = "com.example.android.weatherlistwidget.CLICK";
    public static String REFRESH_ACTION = "com.example.android.weatherlistwidget.REFRESH";
    public static String EXTRA_CITY_ID = "com.example.android.weatherlistwidget.city";

    private static HandlerThread sWorkerThread;
    private static Handler sWorkerQueue;
    private static WeatherDataProviderObserver sDataObserver;

    public WeatherWidgetProvider() {
         sWorkerThread = new HandlerThread("WeatherWidgetProvider-worker"); //开一个线程，这里用到了HandlerThread
        sWorkerThread.start();
        sWorkerQueue = new Handler(sWorkerThread.getLooper()); //不了解Thread的Looper可以看下这个例子比较简单清晰
    }

    @Override
    public void onEnabled(Context context) { //当appWidget添加到桌面上时
           final ContentResolver r = context.getContentResolver();
        if (sDataObserver == null) {
            final AppWidgetManager mgr = AppWidgetManager.getInstance(context);
            final ComponentName cn = new ComponentName(context, WeatherWidgetProvider.class);
            sDataObserver = new WeatherDataProviderObserver(mgr, cn, sWorkerQueue);
            r.registerContentObserver(WeatherDataProvider.CONTENT_URI, true, sDataObserver); //注册监控数据库变化的回调
        }
    }

    @Override
    public void onReceive(Context ctx, Intent intent) {
        final String action = intent.getAction();
        if (action.equals(REFRESH_ACTION)) { //接收数据库改变的回调广播
               final Context context = ctx;
            sWorkerQueue.removeMessages(0);
            sWorkerQueue.post(new Runnable() {
                @Override
                public void run() {
                    final ContentResolver r = context.getContentResolver();
                    final Cursor c = r.query(WeatherDataProvider.CONTENT_URI, null, null, null,
                            null);
                    final int count = c.getCount();
                    final int maxDegrees = 96;

                    r.unregisterContentObserver(sDataObserver); //首先取消数据库监控
                    for (int i = 0; i < count; ++i) {
                        final Uri uri = ContentUris.withAppendedId(WeatherDataProvider.CONTENT_URI, i);
                        final ContentValues values = new ContentValues();
                        values.put(WeatherDataProvider.Columns.TEMPERATURE,
                                new Random().nextInt(maxDegrees));
                        r.update(uri, values, null, null); //更新数据库记录层
                    }
                    r.registerContentObserver(WeatherDataProvider.CONTENT_URI, true, sDataObserver); //重新设置监视数据库

                    final AppWidgetManager mgr = AppWidgetManager.getInstance(context);
                    final ComponentName cn = new ComponentName(context, WeatherWidgetProvider.class);
                    mgr.notifyAppWidgetViewDataChanged(mgr.getAppWidgetIds(cn), R.id.weather_list); //提示Widget有数据更新并刷新UI
                }
            });
        } else if (action.equals(CLICK_ACTION)) {
             final int appWidgetId = intent.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID,
                    AppWidgetManager.INVALID_APPWIDGET_ID);
            final String city = intent.getStringExtra(EXTRA_CITY_ID);
            final String formatStr = ctx.getResources().getString(R.string.toast_format_string);
            Toast.makeText(ctx, String.format(formatStr, city), Toast.LENGTH_SHORT).show();
        }

        super.onReceive(ctx, intent);
    }

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
                 for (int i = 0; i < appWidgetIds.length; ++i) {
                      final Intent intent = new Intent(context, WeatherWidgetService.class);   //当桌面上有多个这个相同的appWidget需要分别处理
            intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetIds[i]);
            intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME)));
            final RemoteViews rv = new RemoteViews(context.getPackageName(), R.layout.widget_layout);
            rv.setRemoteAdapter(appWidgetIds[i], R.id.weather_list, intent);

            rv.setEmptyView(R.id.weather_list, R.id.empty_view);

            final Intent onClickIntent = new Intent(context, WeatherWidgetProvider.class);
            onClickIntent.setAction(WeatherWidgetProvider.CLICK_ACTION);
            onClickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetIds[i]);
            onClickIntent.setData(Uri.parse(onClickIntent.toUri(Intent.URI_INTENT_SCHEME)));
            final PendingIntent onClickPendingIntent = PendingIntent.getBroadcast(context, 0,
                    onClickIntent, PendingIntent.FLAG_UPDATE_CURRENT);
            rv.setPendingIntentTemplate(R.id.weather_list, onClickPendingIntent);

            final Intent refreshIntent = new Intent(context, WeatherWidgetProvider.class);
            refreshIntent.setAction(WeatherWidgetProvider.REFRESH_ACTION);
            final PendingIntent refreshPendingIntent = PendingIntent.getBroadcast(context, 0,
                    refreshIntent, PendingIntent.FLAG_UPDATE_CURRENT);
            rv.setOnClickPendingIntent(R.id.refresh, refreshPendingIntent);

            appWidgetManager.updateAppWidget(appWidgetIds[i], rv);
        }
        super.onUpdate(context, appWidgetManager, appWidgetIds);
    }
}

对于WeatherWidgetService.java这个Service集成于RemoteViewsService,主要是UI上的处理

public class WeatherWidgetService extends RemoteViewsService {
    @Override
    public RemoteViewsFactory onGetViewFactory(Intent intent) {
        return new StackRemoteViewsFactory(this.getApplicationContext(), intent);
    }
}

class StackRemoteViewsFactory implements RemoteViewsService.RemoteViewsFactory {
    private Context mContext;
    private Cursor mCursor;
    private int mAppWidgetId;

    public StackRemoteViewsFactory(Context context, Intent intent) {
        mContext = context;
        mAppWidgetId = intent.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID,
                AppWidgetManager.INVALID_APPWIDGET_ID);
    }

    public void onCreate() {
    }

    public void onDestroy() {
        if (mCursor != null) {
            mCursor.close();
        }
    }

    public int getCount() {
        return mCursor.getCount();
    }

    public RemoteViews getViewAt(int position) {
        String city = "Unknown City";
        int temp = 0;
        if (mCursor.moveToPosition(position)) {
            final int cityColIndex = mCursor.getColumnIndex(WeatherDataProvider.Columns.CITY);
            final int tempColIndex = mCursor.getColumnIndex(
                    WeatherDataProvider.Columns.TEMPERATURE);
            city = mCursor.getString(cityColIndex);
            temp = mCursor.getInt(tempColIndex);
        }

        final String formatStr = mContext.getResources().getString(R.string.item_format_string);
        final int itemId = (position % 2 == 0 ? R.layout.light_widget_item
                : R.layout.dark_widget_item);
        RemoteViews rv = new RemoteViews(mContext.getPackageName(), itemId);
        rv.setTextViewText(R.id.widget_item, String.format(formatStr, temp, city));

        final Intent fillInIntent = new Intent();
        final Bundle extras = new Bundle();
        extras.putString(WeatherWidgetProvider.EXTRA_CITY_ID, city);
        fillInIntent.putExtras(extras);
        rv.setOnClickFillInIntent(R.id.widget_item, fillInIntent);

        return rv;
    }
    public RemoteViews getLoadingView() {
        return null;
    }

    public int getViewTypeCount() {
        return 2;
    }

    public long getItemId(int position) {
        return position;
    }

    public boolean hasStableIds() {
        return true;
    }

    public void onDataSetChanged() {
        if (mCursor != null) {
            mCursor.close();
        }
        mCursor = mContext.getContentResolver().query(WeatherDataProvider.CONTENT_URI, null, null,
                null, null);
    }
}