java - Android GPS不正确的查询位置数据

Question

我没有为此使用模拟位置...事实上，代码就在上周运行良好。

我有一个应用程序可以收集 GPS 数据并使用应用程序本身生成的 X、Y 坐标吐出一个谷歌地图链接。我不是 100% 确定为什么它没有按应有的方式工作，但是当我请求应用程序根据手机提供的 GPS 位置建立谷歌地图链接时，它告诉我我离我的地点有 5 - 6 个街区origin(我当时实际所在的位置)不完全是我想要它做的

已知:

• 我设置了适当的权限
• 上周所有代码都运行良好

这是收集 GPS 信息的代码:

        Toast.makeText(context, "Gathering GPS Data...", Toast.LENGTH_SHORT).show();
    gps = new gpsTracker(Settings.this);
    if(gps.canGetLocation()){
        try{
            gps.getLocation();
            lon = gps.getLongitude();
            lat = gps.getLatitude();
            Toast.makeText(getApplicationContext(), "Your location is - \nlat: " + lat + "\nlon: " + lon, Toast.LENGTH_LONG).show();
        }
        catch(Exception  e){}
    }
    else{
        gps.showSettingsAlert();
    }

以上所有的类都来自:

import android.app.AlertDialog;
import android.app.Service;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;
import android.util.Log;

public class gpsTracker extends Service implements LocationListener {

private final Context mContext;

// flag for GPS status
boolean isGPSEnabled = false;

// flag for network status
boolean isNetworkEnabled = false;

// flag for GPS status
boolean canGetLocation = false;

Location location; // location
double latitude; // latitude
double longitude; // longitude

// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters

// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute

// Declaring a Location Manager
protected LocationManager locationManager;

public gpsTracker(Context context) {
    this.mContext = context;
    getLocation();
}

public Location getLocation() {
    try {
        locationManager = (LocationManager) mContext
                .getSystemService(LOCATION_SERVICE);

        // getting GPS status
        isGPSEnabled = locationManager
                .isProviderEnabled(LocationManager.GPS_PROVIDER);

        // getting network status
        isNetworkEnabled = locationManager
                .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!isGPSEnabled && !isNetworkEnabled) {
            // no network provider is enabled
        } else {
            this.canGetLocation = true;
            // First get location from Network Provider
            if (isNetworkEnabled) {
                locationManager.requestLocationUpdates(
                        LocationManager.NETWORK_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                Log.d("Network", "Network");
                if (locationManager != null) {
                    location = locationManager
                            .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                    if (location != null) {
                        latitude = location.getLatitude();
                        longitude = location.getLongitude();
                    }
                }
            }
            // if GPS Enabled get lat/long using GPS Services
            if (isGPSEnabled) {
                if (location == null) {
                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d("GPS Enabled", "GPS Enabled");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
            }
        }

    } catch (Exception e) {
        e.printStackTrace();
    }

    return location;
}

/**
 * Stop using GPS listener
 * Calling this function will stop using GPS in your app
 * */
public void stopUsingGPS(){
    if(locationManager != null){
        locationManager.removeUpdates(gpsTracker.this);
    }
}

/**
 * Function to get latitude
 * */
public double getLatitude(){
    if(location != null){
        latitude = location.getLatitude();
    }

    // return latitude
    return latitude;
}

/**
 * Function to get longitude
 * */
public double getLongitude(){
    if(location != null){
        longitude = location.getLongitude();
    }

    // return longitude
    return longitude;
}

/**
 * Function to check GPS/wifi enabled
 * @return boolean
 * */
public boolean canGetLocation() {
    return this.canGetLocation;
}

/**
 * Function to show settings alert dialog
 * On pressing Settings button will lauch Settings Options
 * */
public void showSettingsAlert(){
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

    // Setting Dialog Title
    alertDialog.setTitle("GPS is settings");

    // Setting Dialog Message
    alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");

    // On pressing Settings button
    alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,int which) {
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            mContext.startActivity(intent);
        }
    });

    // on pressing cancel button
    alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
        }
    });

    // Showing Alert Message
    alertDialog.show();
}

@Override
public void onLocationChanged(Location location) {
}

@Override
public void onProviderDisabled(String provider) {
}

@Override
public void onProviderEnabled(String provider) {
}

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

@Override
public IBinder onBind(Intent arg0) {
    return null;
}

Answer 1

根据指定的内容 [4-5 个 block 的差异]，您可能仅从 networkProvider 获取 location。

有了问题中提到的这个gpsTracker代码，
需要进行一些修改，而不是按原样使用代码:

1.有 2 个 if 循环验证 location 的来源是否启用并且没有 'else':

 if (isNetworkEnabled) {
                locationManager.requestLocationUpdates(
                        LocationManager.NETWORK_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                Log.d("Network", "Network");
                if (locationManager != null) {
                    location = locationManager
                            .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                    if (location != null) {
                        latitude = location.getLatitude();
                        longitude = location.getLongitude();
                    }
                }
            }
            // if GPS Enabled get lat/long using GPS Services
            if (isGPSEnabled) {
                if (location == null) {
                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d("GPS Enabled", "GPS Enabled");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
            }  

这意味着当您可以从两个来源获取 location 时，应用程序将完成两倍的工作。此外，获取的location 的来源始终是模棱两可的。

当您只需要大概的 location 时这很好，它主要不应该为 null。

如果你只想使用这个类来获取location，请尝试根据要求构造if-else，并确保它不会重复如果location 获取。
Eg. 如果 GPS 具有更高的偏好，适用于您的情况，请将 if 移至上方并将带有 else 的网络状况，例如:

if (isGPSEnabled) {
                if (location == null) {
                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d("GPS Enabled", "GPS Enabled");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
            } else if (isNetworkEnabled) {
            locationManager.requestLocationUpdates(
                    LocationManager.NETWORK_PROVIDER,
                    MIN_TIME_BW_UPDATES,
                    MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
            Log.d("Network", "Network");
            if (locationManager != null) {
                location = locationManager
                        .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                if (location != null) {
                    latitude = location.getLatitude();
                    longitude = location.getLongitude();
                }
            }
        }

根据您的要求，我建议删除网络提供商部分并仅从 GPS 获取位置，尤其是在视线不成问题的情况下。

当您的代码运行良好时，它必须从 GPS 获取位置并将其设置在对象中。但是因为有两个“if”而没有“else”，你永远不知道获取的location是来自网络还是GPS——你可以查看location.getProvider()在 canGetLocation()

的条件下

2.此外，您可以记录消息或针对某个特定来源提示执行某些操作...例如:
在这部分:

 if (!isGPSEnabled && !isNetworkEnabled) {
            // no network provider is enabled
        }    

只需将其分成两个不同的 if(s) 并相应地编写代码。到目前为止，这里什么都没有发生，所以除非你从外部检查，否则你不会知道两者是否都被禁用了。

建议:试试 LocationClient which uses GooglePlayServices对于 Retrieving Current Location .我发现它更可靠、更有用。检查这个Fused Location Provider example , 设置 LocationRequest object根据您的要求是关键。

另一个更新:刚刚遇到:useful ques on stack overflow - Good way of getting the users location

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任何查找此问题/答案的人的更新
关于LocationClient的建议；
在 com.google.android.gms.location 下不再找到 LocationClient ，引用:
Android play services 6.5: LocationClient is missing