How to get current location in Android
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我在使用Android定位系统的NETWORK提供商获取当前位置坐标时遇到了麻烦。
已经阅读了很多教程,并为我的项目实现了4或5个现有的类,所有这些都给了我最后的坐标但不是当前的坐标。
我很确定问题是我缺少的基本问题,但我无法理解究竟是什么。
我现在使用的代码:
这是我的主要活动
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | package com.example.locationtests; import android.os.Bundle; import android.app.Activity; import android.view.Menu; import android.widget.TextView; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); GPSTracker mGPS = new GPSTracker(this); TextView text = (TextView) findViewById(R.id.texts); if(mGPS.canGetLocation ){ mGPS.getLocation(); text.setText("Lat"+mGPS.getLatitude()+"Lon"+mGPS.getLongitude()); }else{ text.setText("Unabletofind"); System.out.println("Unable"); } } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } } |
这是我用于跟踪的课程:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 | package com.example.locationtests; import android.app.AlertDialog; 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.provider.Settings; import android.util.Log; public final class GPSTracker implements LocationListener { private final Context mContext; // flag for GPS status public 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 = 1; // 10 meters // The minimum time between updates in milliseconds private static final long MIN_TIME_BW_UPDATES = 1; // 1 minute // Declaring a Location Manager protected LocationManager locationManager; public GPSTracker(Context context) { this.mContext = context; getLocation(); } /** * Function to get the user's current location * * @return */ public Location getLocation() { try { locationManager = (LocationManager) mContext .getSystemService(Context.LOCATION_SERVICE); // getting GPS status isGPSEnabled = locationManager .isProviderEnabled(LocationManager.GPS_PROVIDER); Log.v("isGPSEnabled","=" + isGPSEnabled); // getting network status isNetworkEnabled = locationManager .isProviderEnabled(LocationManager.NETWORK_PROVIDER); Log.v("isNetworkEnabled","=" + isNetworkEnabled); if (isGPSEnabled == false && isNetworkEnabled == false) { // no network provider is enabled } else { this.canGetLocation = true; if (isNetworkEnabled) { location=null; 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) { location=null; 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) { } } |
这是我的AndroidManifest.xml
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 | <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.locationtests" android:versionCode="1" android:versionName="1.0"> <uses-permission android:name="android.permission.CAMERA" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.INTERNET"></uses-permission> <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <uses-permission android:name="android.permission.VIBRATE" /> <uses-feature android:name="android.hardware.camera" /> <uses-feature android:name="android.hardware.location" android:required="true" /> <uses-feature android:name="android.hardware.location.gps" android:required="false" /> <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="17" /> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme"> <activity android:name="com.example.locationtests.MainActivity" android:label="@string/app_name"> <intent-filter> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest> |
实际上GPS定位工作正常,但NETWORK定位不适用。
当我转动设备时GPS坐标在我移动时不断变化,但当我关闭它并在NETWORK_PROVIDER上转发时也不会发生同样的情况
首先,您需要定义
1 2 3 4 5 6 | private final LocationListener mLocationListener = new LocationListener() { @Override public void onLocationChanged(final Location location) { //your code here } }; |
然后获取
1 2 3 4 5 6 7 8 9 | @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mLocationManager = (LocationManager) getSystemService(LOCATION_SERVICE); mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, LOCATION_REFRESH_TIME, LOCATION_REFRESH_DISTANCE, mLocationListener); } |
最后确保你已经在Manifest上添加了权限,
仅使用基于网络的位置使用此位置
1 | <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/> |
对于基于GPS的位置,这一个
1 | <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/> |
您需要在OnLocationChanged方法中编写代码,因为在位置更改时会调用此方法。即 如果调用getLocation,则需要保存新位置以返回它。
如果您不使用onLocationChanged,它将始终是旧位置。
我正在使用本教程,它适用于我的应用程序。
在我的活动中,我把这段代码:
1 2 3 4 5 6 7 | GPSTracker tracker = new GPSTracker(this); if (!tracker.canGetLocation()) { tracker.showSettingsAlert(); } else { latitude = tracker.getLatitude(); longitude = tracker.getLongitude(); } |
还要检查您的模拟器是否使用Google API运行