给地震监视器添加Notification
在接下来的例子中，EarthquakeService将为每个新的地震触发一个Notification。显示状态条图标的同时，在扩展的状态窗口中显示地震的级别和位置，选择它将会打开Earthquake Activity。
1. 在EarthquakeService中，创建一个新的Notification实例变量来储存Notification对象，用于控制状态条图标和扩展的状态窗口中项目的细节。
private Notification newEarthquakeNotification;
public static final int NOTIFICATION_ID = 1;
2. 扩展onCreate方法来创建Notification对象。
@Override
public void onCreate() {
updateTimer = new Timer(“earthquakeUpdates”);
int icon = R.drawable.icon;
String tickerText = “New Earthquake Detected”;
long when = System.currentTimeMillis();
newEarthquakeNotification= new Notification(icon, tickerText, when);
}
3. 现在，扩展annouceNewQuake方法，在每个新的地震数据添加到ContentProvider之后触发Notification。在初始化Notification之前，使用setLastestEventInfo方法来更新扩展的信息。
private void announceNewQuake(Quake quake) {
String svcName = Context.NOTIFICATION_SERVICE;
NotificationManager notificationManager;
notificationManager = (NotificationManager)getSystemService(svcName);
Context context = getApplicationContext();
String expandedText = quake.getDate().toString();
String expandedTitle = “M:” + quake.getMagnitude() + “ “ +quake.getDetails();
Intent startActivityIntent = new Intent(this, Earthquake.class);
PendingIntent launchIntent = PendingIntent.getActivity(context,0,startActivityIntent,0);
newEarthquakeNotification.setLatestEventInfo(context,expandedTitle,expandedText,launchIntent);
newEarthquakeNotification.when = java.lang.System.currentTimeMillis();
notificationManager.notify(NOTIFICATION_ID, newEarthquakeNotification);
Intent intent = new Intent(NEW_EARTHQUAKE_FOUND);
intent.putExtra(“date”, quake.getDate().getTime());
intent.putExtra(“details”, quake.getDetails());
intent.putExtra(“longitude”, quake.getLocation().getLongitude());
intent.putExtra(“latitude”, quake.getLocation().getLatitude());
intent.putExtra(“magnitude”, quake.getMagnitude());
sendBroadcast(intent);
}
4. 最后一步是在两个Activity类中清除Notification。当应用程序活跃时，通过移除状态图标来完成。
4.1. 在Earthquake Activity中，修改onCreate方法，获取NotificationManager的一个引用。
NotificationManager notificationManager;
@Override
public void onCreate(Bundle icicle) {
[ ... existing onCreate ... ]
String svcName = Context.NOTIFICATION_SERVICE;
notificationManager = (NotificationManager)getSystemService(svcName);
}
4.2. 修改EarthquakeReceiver的onReceive方法。当这个方法执行时，正好是Activity活跃的时候，你可以在这里安全的取消所有的地震Notification。
@Override
public void onReceive(Context context, Intent intent) {
loadQuakesFromProvider();
notificationManager.cancel(EarthquakeService.NOTIFICATION_ID);
}
4.3. 接下来，扩展onResume方法来取消Notification。
@Override
public void onResume() {
notificationManager.cancel(EarthquakeService.NOTIFICATION_ID);
IntentFilter filter;
filter = new IntentFilter(EarthquakeService.NEW_EARTHQUAKE_FOUND);
receiver = new EarthquakeReceiver();
registerReceiver(receiver, filter);
super.onResume();
}
4.4. 在EarthquakeMap Activity中重复相同的过程。
NotificationManager notificationManager;
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.earthquake_map);
ContentResolver cr = getContentResolver();
earthquakeCursor = cr.query(EarthquakeProvider.CONTENT_URI, null, null, null, null);
MapView earthquakeMap = (MapView)findViewById(R.id.map_view);
earthquakeMap.getOverlays().add(new EarthquakeOverlay(earthquakeCursor));
String svcName = Context.NOTIFICATION_SERVICE;
notificationManager = (NotificationManager)getSystemService(svcName);
}
@Override
public void onResume() {
notificationManager.cancel(EarthquakeService.NOTIFICATION_ID);
earthquakeCursor.requery();
IntentFilter filter;
filter = new IntentFilter(EarthquakeService.NEW_EARTHQUAKE_FOUND);
receiver = new EarthquakeReceiver();
registerReceiver(receiver, filter);
super.onResume();
}
public class EarthquakeReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
notificationManager.cancel(EarthquakeService.NOTIFICATION_ID);
earthquakeCursor.requery();
MapView earthquakeMap = (MapView)findViewById(R.id.map_view);
earthquakeMap.invalidate();
}
}
