它是如何工作的 - requestLocationUpdates()+ LocationRequest/Listener

Question

我是新的Android编码器,我在请求更新我的本地化时遇到问题.

我使用http://developer.android.com/training/location/receive-location-updates.html上的教程.

我的应用程序可以处理异常,正确获取纬度和长度,地理编码器可以处理显示地址.但我只询问一次位置 - 或者当位置发生变化时.我想做一些时间间隔.现在我开始实现教程中的代码,它看起来像这样:

public class MainActivity extends Activity implements 
GooglePlayServicesClient.ConnectionCallbacks,
GooglePlayServicesClient.OnConnectionFailedListener,
LocationListener {

private static final int MILLISECONDS_PER_SECOND = 1000;

public static final int UPDATE_INTERVAL_IN_SECONDS = 5;
private static final long UPDATE_INTERVAL =
          MILLISECONDS_PER_SECOND * UPDATE_INTERVAL_IN_SECONDS;

private static final int FASTEST_INTERVAL_IN_SECONDS = 1;
private static final long FASTEST_INTERVAL =
          MILLISECONDS_PER_SECOND * FASTEST_INTERVAL_IN_SECONDS;

private TextView tvStatus;
private TextView tvLatitude;
private TextView tvLongitude;

LocationRequest mLocationRequest;
LocationClient mLocationClient;
Location mCurrentLocation;

boolean bNetworkEnabled;
boolean bGPSEnabled;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);
    tvStatus = (TextView)findViewById(R.id.tvStatus);
    tvLatitude = (TextView)findViewById(R.id.tvLatitude);
    tvLongitude = (TextView)findViewById(R.id.tvLongitude);

    mLocationRequest = LocationRequest.create();
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    mLocationRequest.setInterval(UPDATE_INTERVAL);
    mLocationRequest.setFastestInterval(FASTEST_INTERVAL);
    mLocationClient = new LocationClient(this, this, this);

    checkProviders();
}

因此已经实施了间隔和位置请求.但在链接我给之前有一个评论,我应该用的地方requestLocationUpdates()(可能onCreate(),onStart()并取消对要求onStop()),但我有问题的.所以,Eclipse向我展示了3种方法:

requestLocationUpdates(LocationRequest request, LocationListener listener)
requestLocationUpdates(LocationRequest request, PendingIntent CallbackIntent)
requestLocationUpdates(LocationRequest request, LocationListener listener, Looper looper)

所以我认为第一个在这个地方是最正确的.我应该在LocationListener插槽中放置什么？我请求帮助,解释它是如何工作的.

Answer 1

您正在活动MainActivity中实现LocationListener.对并发位置更新的调用将是这样的:

mLocationClient.requestLocationUpdates(mLocationRequest, this);

确保您正在实施的LocationListener来自google api,即导入此内容:

import com.google.android.gms.location.LocationListener;

而不是这个:

import android.location.LocationListener;

它应该工作得很好.

在执行此操作之前,实际连接LocationClient也很重要.我建议你不要在onCreate或onStart方法中调用它,而是在onResume中调用它.在Google Location Api教程中对此进行了很好的解释:https://developer.android.com/training/location/index.html

Answer 2

我用这个:

LocationManager.requestLocationUpdates(String provider, long minTime, float minDistance, LocationListener listener)

例如,使用1s间隔:

locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,1000,0,this);

时间以毫秒为单位,距离以米为单位.

这会自动调用:

public void onLocationChanged(Location location) {
    //Code here, location.getAccuracy(), location.getLongitude() etc...
}

我也将这些包含在脚本中,但实际上没有使用它们:

public void onStatusChanged(String provider, int status, Bundle extras) {}
public void onProviderEnabled(String provider) {}
public void onProviderDisabled(String provider) {}

简而言之:

public class GPSClass implements LocationListener {

    public void onLocationChanged(Location location) {
        // Called when a new location is found by the network location provider.
        Log.i("Message: ","Location changed, " + location.getAccuracy() + " , " + location.getLatitude()+ "," + location.getLongitude());
    }

    public void onStatusChanged(String provider, int status, Bundle extras) {}
    public void onProviderEnabled(String provider) {}
    public void onProviderDisabled(String provider) {}

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,1000,0,this);
    }
}