软件应用教程

Android 3.0自带的天气预报例子代码 Android开发技术

Android 3.0自带的天气预报例子代码 Android开发技术

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”, 8));
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);
}
}

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