android 开发 - 获取定位信息，解决getLastKnownLocation返回null问题和监听位置变化
1、新建类MyLocation.java，并继承Activity。2、构造函数（可以根据自身需求增删）：public MyLocation(Context _context, MapView _mapView, GraphicsOverlay _locationGOlay){this.context = _context;this.mMapView = _mapVie...
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1、新建类MyLocation.java，并继承Activity。
注意：程序中 Vector2D类需要引入
implementation 'com.vividsolutions:jts-core:1.14.0'2、构造函数（可以根据自身需求增删）：
public MyLocation(Context _context, MapView _mapView, GraphicsOverlay _locationGOlay){
this.context = _context;
this.mMapView = _mapView;
locationGOlay = _locationGOlay;
}3、使用如下：
MyLocation myLocation = new MyLocation(MainActivity.this, mMapView, mGraphicsOverlay);
// 调用定位初始化
myLocation.initLocaltionMethod();4、代码如下：
public static double pi = 3.1415926535897932384626;
public static double x_pi = 3.14159265358979324 * 3000.0 / 180.0;
public static double a = 6378245.0;
public static double ee = 0.00669342162296594323;
private static final int GPS_REQUEST_CODE = 200;
private Context context;
private MapView mMapView;
private LocationManager mLocationManager;
private GraphicsOverlay locationGOlay;
private String mLongitude = ""; // 经度
private String mLatitude = ""; // 维度
/**
* 构造方法
*/
public MyLocation(Context _context,MapView _mapView,GraphicsOverlay _locationGOlay) {
this.context = _context;
this.mMapView = _mapView;
locationGOlay = _locationGOlay;
}
/**
* 初始化定位方法
*/
public void initLocaltionMethod() {
//获取定位服务
mLocationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
//检查NETWORK定位是否被打开
boolean networkIsOpen = mLocationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
//检查passive定位是否被打开
boolean passiveIsOpen = mLocationManager.isProviderEnabled(LocationManager.PASSIVE_PROVIDER);
//检查GPS定位是否被打开
boolean gpsIsOpen = mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
if (networkIsOpen || passiveIsOpen || gpsIsOpen) {
//定位
startLocation();
} else {
Toast.makeText(context,"请打开地理位置",Toast.LENGTH_SHORT).show();
}
}
/**
* 执行定位-判断定位权限
*/
private void startLocation() {
// 判断定位权限
if (ActivityCompat.checkSelfPermission(context,Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED
&& ActivityCompat.checkSelfPermission(context,Manifest.permission.ACCESS_COARSE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
// 调用动态申请权限
requestPermission();
return;
}
/**--用循环获取定位方法--
* 为获取地理位置信息时设置查询条件,
* 是按GPS定位还是NETWORK定位
*/
Location location = getLastKnownLocation();
/** 获取定位信息 **/
upDataLocation(location);
/**--监听位置变化--
* 5 秒更新一次或最小位移变化超过10米更新一次
*
* LocationManager.GPS_PROVIDER 可以替换成 location.getProvider()
* 替换后更新的坐标就不一定是gps定位信息，而是GPS、NETWORK 、PASSIVE其中之一
* */
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,5000,10, gpsListener);
}
/**
* 监听器
* */
LocationListener gpsListener = new LocationListener() {
//当坐标改变时触发此函数，如果Provider传进相同的坐标，它就不会被触发
@Override
public void onLocationChanged(Location location) {
/** 获取gps定位信息-修正定位 **/
upDataLocation(location);
/** 清除定位监听器 **/
removeListener();
}
// Provider 在可用、暂时不可用和无服务三个状态直接切换时触发此函数
@Override
public void onStatusChanged(String provider,int status,Bundle extras) {
}
// Provider被enable时触发此函数，比如GPS被打开
@Override
public void onProviderEnabled(String provider) {
}
// Provider被disable时触发此函数，比如GPS被关闭
@Override
public void onProviderDisabled(String provider) {
}
};
/**
* 清除监听器
* */
public void removeListener() {
if (mLocationManager != null) {
// 清除gps监听器
mLocationManager.removeUpdates(gpsListener);
}
}
/**
* 动态申请权限
*/
private void requestPermission() {
/**
* //22
* Build.VERSION_CODES.LOLLIPOP_MR1
*
* //23
* Build.VERSION_CODES.M
*
* //26
* Build.VERSION_CODES.O
* */
// 判断SDK是否大于23
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
AlertDialog.Builder alter = new AlertDialog.Builder(context);
alter.setTitle("GPS定位权限");
alter.setMessage("是否打开定位权限？");
// 取消
alter.setNegativeButton("取消",new DialogInterface.OnClickListener(){
@Override
public void onClick(DialogInterface dialogInterface, int i) {
// 关闭dialog
dialogInterface.dismiss();
}
});
alter.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
ActivityCompat.requestPermissions((Activity) context,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
GPS_REQUEST_CODE);
}
});
alter.show();
} else {
Toast.makeText(context, "当前SDK版本小于23", Toast.LENGTH_SHORT).show();
}
}
/**
* 执行定位、更新定位
*/
private void upDataLocation(Location location) {
if (location != null) {
/**
* 定位方式：location.getProvider(); - (返回类型：String)
* 经度：location.getLongitude(); - (返回类型：double)
* 纬度：location.getLatitude(); - (返回类型：double)
* 海拔：location.getAltitude(); - (返回类型：double)
* 时间：location.getTime(); - (返回类型：long)
* 速度：location.getSpeed() - (返回类型：float)
* 方向：location.getBearing() - （返回类型：float）
* */
mLongitude = String.valueOf(location.getLongitude());// 经度
mLatitude = String.valueOf(location.getLatitude());// 纬度
/* if (location.getProvider().equals("network")){
Toast.makeText(context, "NETWORK定位经度："+mLongitude+"|"+"维 度："+mLatitude, Toast.LENGTH_SHORT).show();
}else if (location.getProvider().equals("gps")){
Toast.makeText(context, "GPS定位经度："+mLongitude+"|"+"维度："+mLatitude, Toast.LENGTH_SHORT).show();
}else if (location.getProvider().equals("passive")){
Toast.makeText(context, "PASSIVE定位经度："+mLongitude+"|"+"维度："+mLatitude, Toast.LENGTH_SHORT).show();
}*/
double lat = location.getLatitude();
double lon = location.getLongitude();
double[] vv = gps84_To_Gcj02(lat,lon);
Vector2D lonLat = new Vector2D(vv[1],vv[0]);
Vector2D vector2D = lonLatToMercator(lonLat);
Point location_point = new Point(vector2D.getX(),vector2D.getY());
Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(),R.mipmap.location);
BitmapDrawable bitmapDrawable = new BitmapDrawable(bitmap);
PictureMarkerSymbol pictureMarkerSymbol = new PictureMarkerSymbol(bitmapDrawable);
// 创建添加绘制对象图层
Graphic graphic = new Graphic(location_point,pictureMarkerSymbol);
//mMapView.getGraphicsOverlays().add(locationGOlay);
// 清除绘制的信息
locationGOlay.getGraphics().clear();
locationGOlay.getGraphics().add(graphic);
mMapView.setViewpointGeometryAsync(location_point);
mMapView.setViewpointScaleAsync(2000);
} else {
Toast.makeText(context,"获取不到经纬度，请稍后再试",Toast.LENGTH_SHORT).show();
}
}
/**
*循环获取GPS、NETWORK、PASSIVE定位方式
* */
private Location getLastKnownLocation() {
mLocationManager = (LocationManager)context.getSystemService(LOCATION_SERVICE);
List<String> providers = mLocationManager.getProviders(true);
Location bestLocation = null;
for (String provider : providers) {
@SuppressLint("MissingPermission")
Location location = mLocationManager.getLastKnownLocation(provider);
if (location == null) {
continue;
}
if (bestLocation == null || location.getAccuracy() < bestLocation.getAccuracy()) {
bestLocation = location;
}
}
return bestLocation;
}
/**转换坐标*/
public static double transformLat(double x, double y) {
double ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y
+ 0.2 * Math.sqrt(Math.abs(x));
ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(y * pi) + 40.0 * Math.sin(y / 3.0 * pi)) * 2.0 / 3.0;
ret += (160.0 * Math.sin(y / 12.0 * pi) + 320 * Math.sin(y * pi / 30.0)) * 2.0 / 3.0;
return ret;
}
public static double transformLon(double x, double y) {
double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1
* Math.sqrt(Math.abs(x));
ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(x * pi) + 40.0 * Math.sin(x / 3.0 * pi)) * 2.0 / 3.0;
ret += (150.0 * Math.sin(x / 12.0 * pi) + 300.0 * Math.sin(x / 30.0
* pi)) * 2.0 / 3.0;
return ret;
}
/**
* 84 to 火星坐标系 (GCJ-02) World Geodetic System ==> Mars Geodetic System
*
* @param lat
* @param lon
* @return
*/
public static double[] gps84_To_Gcj02(double lat, double lon) {
double dLat = transformLat(lon - 105.0, lat - 35.0);
double dLon = transformLon(lon - 105.0, lat - 35.0);
double radLat = lat / 180.0 * pi;
double magic = Math.sin(radLat);
magic = 1 - ee * magic * magic;
double sqrtMagic = Math.sqrt(magic);
dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
double mgLat = lat + dLat;
double mgLon = lon + dLon;
return new double[]{mgLat, mgLon};
}
/**经纬度转墨卡托投影*/
public Vector2D lonLatToMercator(Vector2D lonLat){
double x = lonLat.getX() * 20037508.34 / 180;
double y = Math.log(Math.tan((90 + lonLat.getY()) * Math.PI / 360)) / (Math.PI / 180);
y = y * 20037508.34 / 180;
Vector2D mercator = new Vector2D(x,y);
return mercator;
}
/**墨卡托投影转经纬度*/
public Vector2D MercatorTolonLat(Vector2D mercator){
double x = mercator.getX() / 20037508.34 * 180;
double y = mercator.getY() / 20037508.34 * 180;
y = 180 / Math.PI * (2 * Math.atan(Math.exp(y * Math.PI / 180)) - Math.PI / 2);
Vector2D lonLat = new Vector2D(x,y);
return lonLat;
}
/**
* 实现 onActivityResult
* 本类必须继承
* AppCompatActivity或者Activity
* */
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode ==GPS_REQUEST_CODE){
startLocation();// 执行定位
}
}
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