Android地图和定位学习总结

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： Interfaces GpsStatus.Listener GpsStatus.NmeaListener LocationListener Classes Address Criteria Geocoder GpsSatellite GpsStatus Location LocationManager LocationProvider com.google.android.maps 包下有这些类： All Classes GeoPoint ItemizedOverlay ItemizedOverlay.OnFocusChangeListener MapActivity MapController MapView MapView.LayoutParams MapView.ReticleDrawMode MyLocationOverlay Overlay Overlay.Snappable OverlayItem Projection TrackballGestureDetector 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);//Loc ationManager 对象只能这么创建，不能用 new Locationlocation=locMan.getLastKnownLocation(LocationManager.GPS_PROVIDE R); if(location==null){ ? ? ? ? ? ? ? ? h t t p ://s h o p 61582462.t a o b a o .c o m / 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

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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 requirement accuracy bearing speed altitude Note that the requirement on monetary cost is not removed in this process. Parameters criteria the criteria that need to be matched enabledOnly if true then only a provider that is currently enabled is returned Returns name of the provider that best matches the requirements only 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 ? ? ? ? ? ? ? ? h t t p ://s h o p 61582462.t a o b a o .c o m / 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;i 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 Constructors Geocoder(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 1 Returns 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 class's 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. Parameters ? ? ? ? ? ? ? ? h t t p ://s h o p 61582462.t a o b a o .c o m / locationNa me a user-supplied description of a location maxResul ts max number of results to return. Smaller numbers (1 to 5) are recommended Returns a list of Address objects. Returns null or empty list if no matches were found or there is no backend service available. Throws IllegalArgumentExce ption if locationName is null IOException if 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); setZoom public 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: ? ? ? ? ? ? ? ? h t t p ://s h o p 61582462.t a o b a o .c o m / 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 @Override public 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 Projection A 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; ? ? ? ? ? ? ? ? h t t p ://s h o p 61582462.t a o b a o .c o m / 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); ? ? ? ? ? ? ? ? h t t p ://s h o p 61582462.t a o b a o .c o m / //---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 the map. This will be called on all active overlays with shadow=true, to lay down the shadow layer, and then again on all overlays with shadow=false. By default, draws nothing. Parameters: canvas - The Canvas upon which to draw. Note that this may already have a transformation applied, so be sure to leave it the way you found it. mapView - the MapView that requested the draw. Use MapView.getProjection() to convert between on-screen pixels and latitude/longitude pairs. ? ? ? ? ? ? ? ? h t t p ://s h o p 61582462.t a o b a o .c o m / shadow - If true, draw the shadow layer. If false, draw the overlay contents. public boolean draw(android.graphics.Canvas canvas, MapView mapView, boolean shadow, long when) when - The timestamp of the draw. Draw call for animated overlays. By default, calls through to draw(Canvas, MapView, boolean) and returns false. Canvas 公共方法 void drawBitmap(Bitmap bitmap, Rect src, Rect dst, Paint paint) Draw the specified bitmap, scaling/translating automatically to fill the destination rectangle. ? ? ? ? ? ? ? ? h t t p ://s h o p 61582462.t a o b a o .c o m /