Java android studio中的GPS设置问题

我是本地android开发的新手。为了理解它，我正在开发一个应用程序，它将向我显示

gps

我的位置。为此，我在网上搜索了两本教程

我遵循

Link1

，并遵循其中的每个步骤，下面是我编写的代码

GPSTracker.java

import android.Manifest;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.provider.Settings;


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;

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 = 5; // 5 meters

// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 10000; // 10 seconds

// Declaring a Location Manager
protected LocationManager locationManager;

public GPSTracker(Context mContext) {
    this.mContext = mContext;
}

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) {
            Log.i("", "Network Value: " + isNetworkEnabled);
            Log.i("", "GPS Value: " + isGPSEnabled);
            // 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 (ActivityCompat.checkSelfPermission(this,  Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED  && ActivityCompat.checkSelfPermission(this,  Manifest.permission.ACCESS_COARSE_LOCATION) !=  PackageManager.PERMISSION_GRANTED) {
    //
    // TODO: Consider calling
   //
  // ActivityCompat#requestPermissions
 //
 // here to request the missing permissions, and then overriding

 // public void onRequestPermissionsResult(int requestCode, String[] permissions,
//
// int[] grantResults)
//
// to handle the case where the user grants the permission. See the documentation

// for ActivityCompat#requestPermissions for more details.

                           return location;

                     }*/
            }
            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();
        Log.i("", "Exception " + e);

    }
    return location;
}

/**
 * Stop using GPS listener
 * Calling this function will stop using GPS in your app
 * */
public void stopUsingGPS() {
    if (locationManager != null) {
        /*if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.
            return;
        }*/
        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();
}

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

@Override
public void onLocationChanged(Location location) {

}

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

}

@Override
public void onProviderEnabled(String provider) {

}

@Override
public void onProviderDisabled(String provider) {

}}

下面是我的主要活动代码

MainActivity.java

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {
Button btnShowLocation;
TextView textShowLocation;
// GPSTracker class
GPSTracker gps;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btnShowLocation = (Button) findViewById(R.id.btnShowLocation);
    // show location button click event
    btnShowLocation.setOnClickListener(new View.OnClickListener(){


        @Override
        public void onClick(View v) {
            // create class object
            gps = new GPSTracker(MainActivity.this);
            // need to make canGetLocation flag true by calling below method as per your code.
            **gps.getLocation()**
            // check if GPS enabled
            if(gps.canGetLocation()){
                double latitude = gps.getLatitude();
                double longitude = gps.getLongitude();
                textShowLocation.append("Your Location is - \nLat: " + latitude+ "\nLong: " + longitude);
            }
            else
            {
                // can't get location
                // GPS or Network is not enabled
                // Ask user to enable GPS/network in settings
                gps.showSettingsAlert();
            }
        }
    });



}

更新1

以下是我的舱单代码：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.accurat.tracker">
<uses-sdk android:minSdkVersion="8" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

在我的设备中运行应用程序时，每当我单击

显示位置

按钮时，它总是将我重定向到

其他

部分，即

gps.showSettingsAlert（）运行。不管我的设备的“GPS”是否在上面，它仍然不会显示我的位置。此外，对
权限检查进行注释或取消注释也无济于事

如果您使用的是5.0+版本，我们将非常感谢您的帮助。

然后加上


到你的舱单。
如果你正在测试棉花糖，你必须添加

int REQUEST_CODE_PERMISSION=101;
    void allowGPS() {
            try {
                if (Build.VERSION.SDK_INT >= 23 {
                    Log.i("*******", "check build permission");
                    try {
                        if (getApplicationContext().checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                            if (ActivityCompat.shouldShowRequestPermissionRationale(LoginActivity.this, Manifest.permission.ACCESS_FINE_LOCATION)) {
                                // permission wasn't granted
                            } else {
                                ActivityCompat.requestPermissions(LoginActivity.this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_CODE_PERMISSION);
                            }
                        }
                    } catch (Exception ae) {

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



 @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        if (requestCode == REQUEST_CODE_PERMISSION) {
            if (grantResults.length >= 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                // permission was granted
            } else {
                // permission wasn't granted
            }
        }
    }

GPSTracker是一个服务类。您必须启动服务才能获取位置。现在显示else条件，因为尚未获取位置。
您可以通过以下方式开始服务：
startService（新意图（context，GPSTracker.class））

也可以通过以下方式更改按钮单击代码

 LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

    if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)){
        Toast.makeText(this, "GPS is Enabled in your devide", Toast.LENGTH_SHORT).show();
    }else{
        showGPSDisabledAlertToUser();
    }

您需要调用
getLocation
（）；构造函数中的方法：

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

在GPSTracker类中添加以下代码：

 @Override
public void onLocationChanged(Location location) {
    this.location = location;
    getLatitude();
    getLongitude();
}

你使用的类也有一些问题：请看这个博客

您可以使用
FusedLocationApi

下面是一个示例：
您是否正确设置了
清单上的权限？@ThisaruGuruge请查看
更新1
您是否尝试了多台设备？@faisal1208告诉我们您正在测试的设备的完整详细信息。。它的API级别和代码块，它将从中访问。。调试并检查if-else条件您获得的值，然后只有我们可以提供帮助。正如我看到的代码一样，最小的sdk是
android:minSdkVersion=“8”
为什么您对我们撒谎？通过实现您的逻辑，现在在
按钮上单击
我的应用程序崩溃，并给我消息
，不幸的是，Tracker已停止
它在logcat中给了我这个错误
致命异常：主进程：com.example.accurat.Tracker，PID:10668 java.lang.NullPointerException:尝试调用虚拟方法'void android.widget.TextView.append（java.lang.CharSequence）'在空对象引用上
您需要首先使用布局中的
findviewByID
实例化
textShowLocation
，现在它正在运行，但它显示的是lat，long
0,0
：|尝试更改
MIN\u DISTANCE\u CHANGE\u以更新
和
MIN\u TIME\u BW\u更新
到
0,0
，并检查编辑