关于获取当前位置的问题

  我编写了一个程序主要实现2个功能一是显示用户当前位置二是查询周围商铺现在第一个完成了第二个还差点主要差在怎么把查询出来的在数据库中的经纬度显示在地图上过程是这样的：主界面（显示我当前的位置）——》查询界面（各种条件）——》返回所要查询位置的经纬度——》回到主界面显示商铺位置并且连接路径
  但是在返回主界面的时候虽然我传回了经纬度但是手机适中聚焦在开始设定的位置不变，后来我又创建了一个文件希望在这个文件里显示我传过来的经纬度但是同样遇到了问题，代码如下：
public class destination extends MapActivity implements LocationListener{
double getlatitude,getlongitude;
private LocationManager locationmanager;
String bestProvider;
private MapController mapcontroller;
private GeoPoint geopoint;
MyPositionOverlay positionOverlay; public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.destination);

MapView destination_mapView = (MapView) findViewById(R.id.destination_mapView);
mapcontroller = destination_mapView.getController();
destination_mapView.setBuiltInZoomControls(true);
destination_mapView.setTraffic(true);
// Add the MyPositionOverlay
    positionOverlay = new MyPositionOverlay();
    List<Overlay> overlays = destination_mapView.getOverlays();
    overlays.add(positionOverlay);

locationmanager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_COARSE);// 低精度
criteria.setPowerRequirement(Criteria.POWER_LOW);// 低能耗
criteria.setAltitudeRequired(false);// 不要求海拔
criteria.setBearingRequired(false);// 不要求方向
criteria.setSpeedRequired(false);// 不要求速度
bestProvider = locationmanager.getBestProvider(criteria, true);// 将符合条件的Provider放在字符串bestProvider中
//Location destination = locationmanager.主要就是这句！！！！这句！！！看到没就这句！！！

Intent descriptionTodestination = getIntent();
getlatitude = descriptionTodestination.getDoubleExtra("latitude", getlatitude);
getlongitude = descriptionTodestination.getDoubleExtra("longitude", getlongitude);
//System.out.println(getlatitude+" "+getlongitude);

}
在得到Provider的时候调用locationmanager的方法，但是我不知道调用什么方法啊？下边是传过来的经纬度，究竟怎么能让屏幕聚焦到传递过来的经纬度的位置而不是在DDMS中一次次的设定啊！！！！

解决方案 »

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你可以看看红色字体部分代码，他就是根据经纬度聚焦到屏幕中心的
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.List;
import java.util.Locale;import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Point;
import android.location.Address;
import android.location.Criteria;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.TextView;import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
public class MyLocation extends MapActivity{

private MapView mMapView;
private MapController mMapController;
private MyLocationOverlay myPosition;
private String GpsData;

@Override
protected void onCreate(Bundle icicle) {
// TODO Auto-generated method stub
super.onCreate(icicle);
setContentView(R.layout.main);
LocationManager locationManager;
String context = Context.LOCATION_SERVICE;
locationManager = (LocationManager) getSystemService(context);
mMapView = (MapView) findViewById(R.id.map);
mMapView.setTraffic(false);
mMapView.setSatellite(true);
mMapView.setStreetView(false);
mMapController = mMapView.getController();
mMapView.setEnabled(true);
mMapView.setClickable(true);
mMapView.setBuiltInZoomControls(true);
mMapController.setZoom(17);
myPosition = new MyLocationOverlay();
List<Overlay> overlays = mMapView.getOverlays();
overlays.add(myPosition);
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setCostAllowed(false);
criteria.setPowerRequirement(Criteria.POWER_LOW);
String provider = locationManager.getBestProvider(criteria, true);
Location location = locationManager.getLastKnownLocation(provider);
updateWithNewLocation(location);
locationManager.requestLocationUpdates(provider, 3000, 0, locationListener);
}

private void updateWithNewLocation(Location location){
String latLongString;
TextView myLocationText = (TextView) findViewById(R.id.TextView01);
String addressString = "没有找到地址\n";
if (location != null) {
myPosition.setMLocation(location);
Double geoLat = location.getLatitude()*1E6;
Double geoLng = location.getLongitude()*1E6;
GeoPoint point = new GeoPoint(geoLat.intValue(), geoLng.intValue());
mMapController.animateTo(point);
double latitude = location.getLatitude();
double longitude = location.getLongitude();
latLongString = "经度：" + latitude + "\n纬度：" + longitude;
GpsData = latLongString;
Geocoder gc = new Geocoder(this, Locale.getDefault());
try {
List<Address> addresses = gc.getFromLocation(latitude, longitude, 1);
StringBuilder sb = new StringBuilder();
if (addresses.size() > 0) {
Address address = addresses.get(0);
for (int i = 0; i < address.getMaxAddressLineIndex(); i++) {
sb.append(address.getAddressLine(i)).append("\n");
sb.append(address.getLocality()).append("\n");
sb.append(address.getPostalCode()).append("\n");
sb.append(address.getCountryName()).append("\n");
addressString = sb.toString();
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
else {
latLongString = "没有找到坐标：\n";
}
myLocationText.setText("你当前的坐标如下：\n" + latLongString
+ "\n" + addressString);
} private final LocationListener locationListener = new LocationListener(){
public void onLocationChanged(Location location){
updateWithNewLocation(location);
} @Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
updateWithNewLocation(null);
} @Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub

} @Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub

}
};

@Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}

class MyLocationOverlay extends Overlay{

Location mLocation; public void setMLocation(Location location) {
mLocation = location;
} @Override
public boolean draw(Canvas canvas, MapView mapView, boolean shadow,
long when) {
// TODO Auto-generated method stub
super.draw(canvas, mapView, shadow);
Paint paint = new Paint();
Point myScreenCoords = new Point();
GeoPoint tmpGeoPoint = new GeoPoint((int)(mLocation.getLatitude()*1E6),
(int)(mLocation.getLongitude()*1E6));
mapView.getProjection().toPixels(tmpGeoPoint, myScreenCoords);
paint.setStrokeWidth(1);
paint.setARGB(255, 255, 0, 0);
paint.setStyle(Paint.Style.STROKE);
Bitmap bmp = BitmapFactory.decodeResource(getResources(),
android.R.drawable.btn_star_big_on);
canvas.drawBitmap(bmp, myScreenCoords.x, myScreenCoords.y, paint);
canvas.drawText("here am I", myScreenCoords.x, myScreenCoords.y, paint);
return true;

}
}}
    你这个location 是通过Location location = locationManager.getLastKnownLocation(provider); 这句话注意这个getLastKnownLocation这个函数是返回当前位置的不是返回我制定的位置我不是要返回DDMS设定的位置而是通过intent传过来的两个double型的变量
    你写的程序将已经设定了经纬度的location通过updateWithNewLocation(location);传到函数中在这个函数中的myPosition是OverLay类型的通过myPosition.setMyLocation(location)来设定图层所图的位置与上边传入的location位置保持一致也就是说地图本身是给定的位置图层图的也是该位置
    主要就是这个getLastKnownLocation函数返回的是在DDMS中设定的位置啊！我不要这样的不过也谢谢你这个代码我见过书上的我写过
你看看这个啊
GeoPoint tmpGeoPoint = new GeoPoint((int)(mLocation.getLatitude()*1E6),
(int)(mLocation.getLongitude()*1E6));
你把经纬度传到这里面不就行了，都叫你看红色字体部分了
这个方法我写过不好使我是这样写的流程这样
GeoPoint tmpGeoPoint = new GeoPoint((int)(getLatitude()*1E6),
(int)（getLongitude()*1E6)); 里边的getLatitude和getLongitude是通过intent传过来的值然后在有一个什么来的我给你粘贴 mapcontroller.animateTo(gp); mapcontroller.setZoom(17);来聚焦到这个点上但是有编译错误没通过
现在的主要问题是我无法得到location 你给我写的代码是通过getLastKnownLoaction来获得当前位置的我要的是通过我传递过来的经纬度来定义一个新的location 你看上边那个gp里边的值不都是通过location 或者 mylocation来取得经纬度的吗？
这样写就可以把你传进去的经纬度设置在屏幕中心位置了，
MapController controller;
GeoPoint station_beijing = new GeoPoint(
                        (int)(39.928416*1000000),
(int)(116.139729*1000000)
controller.animateTo(station_beijing);
GeoPoint station_beijing = new GeoPoint(
  (int)(39.928416*1000000),
(int)(116.139729*1000000);
这句少了个分号
貌似少发了点东西
map = (MapView) findViewById(R.id.map);
controller = map.getController();
直接写数值啊……那我和用double变量代替数值有什么区别啊…… 我输出过传过来的getLatitude和getLongitude，输出的数值就是我要的我的代码只不过是写的变量现在全乱套了又说我数据库没关在onDestory中写了关闭有又说我图层里边代码有问题确实是有问题我的图层传进去的是Location类型的变量，通过Location.latitude和location.longitude得到经纬度的啊啊啊啊……后天交我疯了
我解决了一半
在新的地方的图层我还是用旧的涂层文件看来不行因为久的是有Location的但是我新的地方不知道怎么创建Location中的经纬度所以无法用location.latitude 和 location.longitude来得到经纬度看来我要重新写涂层文件了不过不合理啊……谁知道怎么把经纬度设定在一个location里边啊！！这是问题的关键！
试试location.setLatitude(double latitude);
location.setLongitude(double longitude);
貌似不好使抛出空指针异常信息怪了我输出了latitude和longitude里边都有值啊
destination.setLatitude(getlatitude);
destination.setLongitude(getlongitude);
mapView.setBuiltInZoomControls(true);
mapView.setTraffic(true); destination_overlay = new destination_overlay();
//overlays.add(destination, object)
System.out.println(destination.toString());
positionOverlay.setLocation(destination);
System.out.println("123");第一个输出可以输出位置第二个123输出不了下面是overlay代码
package fty.hereami;import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.RectF;
import android.location.Location;
import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import com.google.android.maps.Projection;public class destination_overlay extends Overlay {  private final int mRadius = 5;  Location location;

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

  @Override
  public boolean onTap(GeoPoint point, MapView mapView) {
    return false;
  }

  @Override
  public void draw(Canvas canvas, MapView mapView, boolean shadow) {
    Projection projection = mapView.getProjection();    if (shadow == false) {
      // Get the current location
      Double latitude = location.getLatitude()*1E6;
      Double longitude = location.getLongitude()*1E6;
      //System.out.println(""+latitude+" "+longitude+123);
      GeoPoint geoPoint;
      geoPoint = new
        GeoPoint(latitude.intValue(),longitude.intValue());      // Convert the location to screen pixels
      Point point = new Point();
      projection.toPixels(geoPoint, point);      RectF oval = new RectF(point.x - mRadius, point.y - mRadius,
                             point.x + mRadius, point.y + mRadius);      // Setup the paint
      Paint paint = new Paint();
      paint.setARGB(250, 255, 255, 255);
      paint.setAntiAlias(true);//好像是设置边缘平滑
      paint.setFakeBoldText(true);//设置假的黑体点不知道什么意思      Paint backPaint = new Paint();
      backPaint.setARGB(175, 50, 50, 50);
      backPaint.setAntiAlias(true);      RectF backRect = new RectF(point.x + 2 + mRadius,
                                 point.y - 3*mRadius,
                                 point.x + 65, point.y + mRadius);      // Draw the er
      canvas.drawOval(oval, paint);
      canvas.drawRoundRect(backRect, 5, 5, backPaint);
      canvas.drawText("It's Here!",
                      point.x + 2*mRadius, point.y,
                      paint);
    }
    super.draw(canvas, mapView, shadow);
  }
}