Android地图和定位学习总结.doc

精品Android地图和定位学习总结首届 Google 暑期大学生博客分享大赛2010 Android 篇android.location包下有这么一些接口和类：InterfacesGpsStatus.ListenerGpsStatus.NmeaListenerLocationListenerClassesAddressCriteriaGeocoderGpsSatelliteGpsStatusLocationLocationManagerLocationProvidercom.google.android.maps包下有这些类：All ClassesGeoPointItemizedOverlayItemizedOverlay.OnFocusChangeListenerMapActivityMapControllerMapViewMapView.LayoutParamsMapView.ReticleDrawModeMyLocationOverlayOverlayOverlay.SnappableOverlayItemProjectionTrackballGestureDetector我们边看代码边熟悉这些类。 要获取当前位置坐标，就是从Location对象中获取latitude和longitude属性。那Location对象是如何创建的？LocationManager locMan=(LocationManager)getSystemService(Context.LOCATION_SERVICE);/LocationManager对象只能这么创建，不能用newLocationlocation=locMan.getLastKnownLocation(LocationManager.GPS_PROVIDER);if(location=null) location=locMan.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);/注意要为应用程序添加使用权限 所谓getLastKnownLocation自然是获取最新的地理位置信息，那LocationManager.GPS_PROVIDER和LocationManager.NETWORK_PROVIDER有什么区别呢？俺也不是学通信的，对这个不了解，在网上看到有人想“在室外有GPS定位，在室内想用Wifi或基站定位”。除了直接使用LocationManager提供的静态Provider（如GPS_PROVIDER和NETWORK_PROVIDER等）外，还可以使用我们自己创建的LocationProvider对象。创建LocationProvider对象一般要先创建Criteria对象，来设置我们的LocationProvider要满足什么样的标准Criteria myCri=new Criteria();myCri.setAccuracy(Criteria.ACCURACY_FINE);/精确度myCri.setAltitudeRequired(false);/海拔不需要myCri.setBearingRequired(false);/Bearing是“轴承”的意思，此处可理解为地轴线之类的东西，总之Bearing Information是一种地理位置信息的描述myCri.setCostAllowed(true);/允许产生现金消费myCri.setPowerRequirement(Criteria.POWER_LOW);/耗电String myProvider=locMan.getBestProvider(myCri,true);public String getBestProvider (Criteria criteria, boolean enabledOnly)Returns the name of the provider that best meets the given criteria. Only providers that are permitted to be accessed by the calling activity will be returned. If several providers meet the criteria, the one with the best accuracy is returned. If no provider meets the criteria, the criteria are loosened in the following sequence:power requirementaccuracybearingspeedaltitudeNote that the requirement on monetary cost is not removed in this process.Parameterscriteria the criteria that need to be matchedenabledOnly if true then only a provider that is currently enabled is returnedReturnsname of the provider that best matches the requirementsonly翻译为“最适合的Location location=locMan.getLastKnownLoation(myProvider);double latitude=location.getLatitude();/获取纬度double longitude=location.getLongitude();/获取经度我想知道当前位置描述（比如“武汉华中科技大学”而不是一个经纬值）呢？这就要使用GeoCoder创建一个Address对象了。Geocoder gc=new Geocoder(context,Locale.CHINA);/Locale是java.util中的一个类List listAddress=gc.getFromLocation(latitude,longitude,1);List getFromLocation(double latitude, double longitude, int maxResults)Returns an array of Addresses that are known to describe the area immediately surrounding the given latitude and longitude.(返回给定经纬值附近的一个Address）既然是“附近”那实际编码时我们没必要把经纬值给的那么精确，而取一个近似的整数，像这样：/*自经纬度取得地址，可能有多行地址*/List listAddress=gc.getFromLocation(int)latitude,(int)longitude,1);StringBuilder sb=new StringBuilder();/*判断是不否为多行*/if(listAddress.size()0) Address address=listAddress.get(0);for(int i=0;iaddress.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);public int getMaxAddressLineIndex ()Since: API Level 1Returns the largest index currently in use to specify an address line. If no address lines are specified, -1 is returned.public String getAddressLine (int index)Since: API Level 1Returns a line of the address numbered by the given index (starting at 0), or null if no such line is present.String getCountryName()Returns the localized country name of the address, for example Iceland, or null if it is unknown.String getLocality()Returns the locality of the address, for example Mountain View, or null if it is unknown. 反过来我们可以输入地址信息获取经纬值Geocoder mygeoCoder=new Geocoder(myClass.this,Locale.getDefault();List lstAddress=mygeoCoder.getFromLocationName(strAddress,1);/strAddress是输入的地址信息if(!lstAddress.isEmpty()Address address=lstAddress.get(0);double latitude=address.getLatitude()*1E6;double longitude=adress.getLongitude()*1E6;GeoPoint geopoint=new GeoPoint(int)latitude,(int)longitude); A class for handling geocoding and reverse geocoding. Geocoding is the process of transforming a street address or other description of a location into a (latitude, longitude) coordinate. Public ConstructorsGeocoder(Context context, Locale locale)Constructs a Geocoder whose responses will be localized for the given Locale.Geocoder(Context context)Constructs a Geocoder whose responses will be localized for the default system Locale.public List getFromLocationName (String locationName, int maxResults)Since: API Level 1Returns an array of Addresses that are known to describe the named location, which may be a place name such as Dalvik, Iceland, an address such as 1600 Amphitheatre Parkway, Mountain View, CA, an airport code such as SFO, etc. The returned addresses will be localized for the locale provided to this classs constructor.The query will block and returned values will be obtained by means of a network lookup. The results are a best guess and are not guaranteed to be meaningful or correct. It may be useful to call this method from a thread separate from your primary UI thread.ParameterslocationNamea user-supplied description of a locationmaxResultsmax number of results to return. Smaller numbers (1 to 5) are recommendedReturnsa list of Address objects. Returns null or empty list if no matches were found or there is no backend service available.ThrowsIllegalArgumentExceptionif locationName is nullIOExceptionif the network is unavailable or any other I/O problem occurs 说了半天还只是个定位，地图还没出来。下面要用到com.google.android.maps包了下面的代码我们让地图移到指定点GeoPoint p=new GeoPoint(int)(latitude*1E6),(int)(longitude*1E6);MapView mapview=(MapView)findViewById(R.id.mv);MapController mapContr=mapview.getController();mapview.displayZoomControls(true);/显示地图缩放的按钮mapContr.animateTo(p);/带动画移到p点mapContr.setZoom(7);setZoompublic int setZoom(int zoomLevel)Sets the zoomlevel of the map. The value will be clamped to be between 1 and 21 inclusive, though not all areas have tiles at higher zoom levels. This just sets the level of the zoom directly; for a step-by-step zoom with fancy interstitial animations, use zoomIn() or zoomOut().Parameters:zoomLevel - At zoomLevel 1, the equator of the earth is 256 pixels long. Each successive zoom level is magnified by a factor of 2.Returns:the new zoom level, between 1 and 21 inclusive.在地图上指定一点给出经纬值Overridepublic boolean onTouchEvent(MotionEvent ev)int actionType=ev.getAction();switch(actionType)case MotionEvent.ACTION_UP:Projection projection=mapview.getProjection();GeoPoint loc=projection.fromPixels(int)arg0.getX(),(int)arg0.getY();String lngStr=Double.toString(loc.getLongitudeE6()/1E6);String latStr=Double.toString(loc.getLatitudeE6()/1E6);return false;public interface ProjectionA Projection serves to translate between the coordinate system of x/y on-screen pixel coordinates and that of latitude/longitude points on the surface of the earth. You obtain a Projection from MapView.getProjection(). 如果需要我们还可以把经纬值转换成手机的屏幕坐标值Point screenCoords=new Point(); /android.graphics.Point;GeoPoint geopoint=new GeoPoint(int)(latitude*1E6),(int)(longitude*1E6);mapview.getProjection().toPixels(geopoint,screenCoords);int x=screenCoords.x;int y=screenCoords.y;放大缩小地图主要就是用setZoom(int ZoomLevel)函数,让ZoomLevel不停往上涨（或往下降）就可以了下面给出一个com.google.android.maps.Overlay的使用例子 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;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Point;import android.os.Bundle;import android.view.View; public class MapsActivity extends MapActivity MapView mapView; MapController mc; GeoPoint p; class MapOverlay extends com.google.android.maps.Overlay Override public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when) super.draw(canvas, mapView, shadow); /-translate the GeoPoint to screen pixels- Point screenPts = new Point(); mapView.getProjection().toPixels(p, screenPts); /-add the marker- Bitmap bmp = BitmapFactory.decodeResource( getResources(), R.drawable.pushpin); canvas.drawBitmap(bmp, screenPts.x, screenPts.y-50, null); return true; /* Called when the activity is first created. */ Override public void onCreate(Bundle savedInstanceState) /. Override protected boolean isRouteDisplayed() / TODO Auto-generated method stub return false; public void draw(android.graphics.Canvas canvas, MapView mapView, boolean shadow)Draw the overlay over