将 Android 应用程序中的 GPS 功能外包给一个单独的类

Question

我关注了 http://developer.android.com/guide/topics /location/obtaining-user-location.html 并且在 onCreate 方法中的活动中时效果很好。

然后我想将此功能外包到一个名为 LocationHelper 的单独类中。

import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;

public class LocationHelper {

public Context mContext;
public Location loc;

public LocationHelper (Context mContext){
    this.mContext = mContext;

    // Acquire a reference to the system Location Manager
    LocationManager locationManager = (LocationManager)     mContext.getSystemService(Context.LOCATION_SERVICE);

    // Define a listener that responds to location updates
    LocationListener locationListener = new LocationListener() {
        public void onLocationChanged(Location location) {
          // Called when a new location is found by the network location provider.
            setLocation(location);
        }

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

        public void onProviderEnabled(String provider) {}

        public void onProviderDisabled(String provider) {}
      };

    // Register the listener with the Location Manager to receive location updates
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}

public void setLocation(Location location) {
    this.loc = location;
}

public Location getLocation() {
    return this.loc;
}
}

在活动中我这样做；基本上我想从我的助手类中提取（出于测试目的！）GPS 坐标并显示它。问题是，该位置始终为空。

public class GraffitiWall extends Activity {

private TextView tv;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    tv = new TextView(this);

    LocationHelper gpsie = new LocationHelper(this);
    while (true){
        makeUseOfNewLocation(gpsie.getLocation());
    }
}

public void makeUseOfNewLocation(Location loc){
    if (loc == null){return;}
    tv.setText("" + loc.getLatitude());
    setContentView(tv);
}
}

我错过了什么并且做错了什么？

Answer 1

在 onCreate 方法中放置无限循环是一个坏主意。您的问题很可能是因为 onCreate 永远不会完成并将控制权传递回操作系统而引起的。如果这导致强制关闭错误，我不会感到惊讶。

也许您需要做的是创建一项服务来监视您的位置并从那里更新您的活动。