我有服务。该服务在完成后启动另一个线程，我需要启动一个名为 MapPage.class 的新片段活动，它显示谷歌地图。该线程从包含 GPS 坐标的服务器获取 json。我将这些坐标保存在单例类中。因此，在线程完成后，我需要使用单例类中的数据启动 MapPage 片段活动。
我不知道如何从后台线程启动 MapPage.class。我已经从主要活动中看到了使用处理程序的示例，但我不确定如何将其应用于我的问题。我能找到的最接近的答案是这个。
我想知道创建处理程序是否是我唯一的选择？如果还有其他选择吗？在应用程序类中使用处理程序是否适合我的问题？
我的服务类：
public class TrackingService extends Service {
private class MyLocationListener implements LocationListener {
private final Context context;
public MyLocationListener(Context context) {
this.context = context;
}
@Override
public void onLocationChanged(Location location) {
double latitude = location.getLatitude();
double longtude = location.getLongitude();
double altitude = location.getAltitude();
double accuracy = location.getAccuracy();
float bearing = location.getBearing();
String provider = location.getProvider();
Cood cood = new Cood(latitude, longtude, altitude, accuracy,
new Date().getTime(), bearing, provider);
LocationInformation.getInstanceof().getMapPoint().getCood()
.add(cood);
int size = LocationInformation.getInstanceof().getMapPoint()
.getCood().size();
mBuilder.setContentTitle("GPS Tracker - " + size + "/"
+ SystemSettings.getInstanceOf().getSize());
NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
manager.notify(1, mBuilder.build());
if (size >= SystemSettings.getInstanceOf().getSize()) {
Toast.makeText(context, "before creating new thread for Track",
Toast.LENGTH_SHORT).show();
new Thread(new Track(context)).start();
Toast.makeText(context, "after creating new thread for Track",
Toast.LENGTH_SHORT).show();
}
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
}
LocationManager manag;
LocationListener locationListener;
private Context context;
private Long frequency;
private Integer minDistance;
private String deviceRegNo;
private Integer pointCount;
private Boolean mode;
private Builder mBuilder;
@Override
public void onCreate() {
super.onCreate();
context = this;
}
@Override
public IBinder onBind(Intent arg0) {
return null;
}
@Override
public void onDestroy() {
super.onDestroy();
}
@Override
public boolean onUnbind(Intent intent) {
return super.onUnbind(intent);
}
@Override
public void onTaskRemoved(Intent rootIntent) {
}
@Override
public void onLowMemory() {
super.onLowMemory();
}
@Override
public void onRebind(Intent intent) {
super.onRebind(intent);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
if (intent == null) {
return Service.START_STICKY;
}
manag = (LocationManager) context
.getSystemService(Context.LOCATION_SERVICE);
locationListener = new MyLocationListener(context);
frequency = (Long) intent.getExtras().get("frequency");
minDistance = (Integer) intent.getExtras().get("minDistance");
deviceRegNo = (String) intent.getExtras().get("deviceRegNo");
pointCount = (Integer) intent.getExtras().get("pointCount");
mode = (Boolean) intent.getExtras().get("prodMode");
if (frequency == null) {
Toast.makeText(context, "frequency null", Toast.LENGTH_SHORT)
.show();
return Service.START_STICKY;
}
if (minDistance == null) {
return Service.START_STICKY;
}
if (deviceRegNo == null) {
return Service.START_STICKY;
}
if (pointCount == null) {
Toast.makeText(context, "pointCount null", Toast.LENGTH_SHORT)
.show();
return Service.START_STICKY;
}
if (mode == null) {
Toast.makeText(context, "mode is null", Toast.LENGTH_SHORT).show();
return Service.START_STICKY;
}
if (LocationInformation.getInstanceof().getMapPoint().getDevice() == null) {
Device device = new Device();
device.setDeviceRegNo(deviceRegNo);
LocationInformation.getInstanceof().getMapPoint().setDevice(device);
}
SystemSettings.getInstanceOf().setSize(pointCount);
SystemSettings.getInstanceOf().setProdMode(mode);
Toast.makeText(context, "On the line before pendingIntent statement",
Toast.LENGTH_SHORT).show();
Intent resultIntent = new Intent(context, SettingScreen.class);
PendingIntent resultPendingIntent = PendingIntent.getActivity(this, 0,
resultIntent, PendingIntent.FLAG_UPDATE_CURRENT);
int size = LocationInformation.getInstanceof().getMapPoint().getCood()
.size();
mBuilder = new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.ic_launcher)
.setContentTitle("GPS Tracker - " + size + "/" + pointCount)
.setContentText(
LocationInformation.getInstanceof().getMapPoint()
.getDevice().getDeviceRegNo())
.setContentIntent(resultPendingIntent);
Toast.makeText(context, "On the line after NotificationCompat.builder",
Toast.LENGTH_SHORT).show();
Notification notification = mBuilder.build();
Toast.makeText(context, "On the line after mBuilder.build",
Toast.LENGTH_SHORT).show();
startForeground(1, notification);
Toast.makeText(context, "On the line after startForeground",
Toast.LENGTH_SHORT).show();
manag.requestLocationUpdates(LocationManager.GPS_PROVIDER, frequency,
minDistance, locationListener);
return Service.START_STICKY;
}
}
我的线程代码是：
HttpResponse response = httpClient.execute(httpPost);
BufferedReader br = new BufferedReader(new InputStreamReader(
response.getEntity().getContent()));
String line = "";
while ((line = br.readLine()) != null) {
text += line;
System.out.println("RESULT: " + line);
}
MapCoords.getInstanceof().setMapPoint(
(gson.fromJson(jsonString, MapCoords.class)).getMapPoint());
我必须在这里启动 MapPage Activity。我的 MapPage Activity 代码如下：
public class MapPage extends FragmentActivity {
ArrayList<Cood> cd = MapCoords.getInstanceof().getMapPoint().getCood();
Double latitude = cd.get(0).getLatitude();
Double longitude = cd.get(0).getLongitude();
LatLng point1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.basic_demo);
Toast.makeText(this, "Entered MapPage Activity", Toast.LENGTH_LONG)
.show();
setUpMapIfNeeded();
}
@Override
protected void onResume() {
super.onResume();
setUpMapIfNeeded();
}
private void setUpMapIfNeeded() {
if (mMap == null) {
mMap = ((SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map)).getMap();
point1 = new LatLng(latitude, longitude);
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(point1, 17));
if (mMap != null) {
setUpMap();
}
}
}
private void setUpMap() {
mMap.addMarker(new MarkerOptions()
.position(point1)
.title("Point1")
.snippet("This is the first GPS co-ordinate"));
}
}