Android地圖和定位學習總結

android.location包下有這麼一些接口和類：
Interfaces
GpsStatus.Listener
GpsStatus.NmeaListener
LocationListener
Classes
Address
Criteria
Geocoder
GpsSatellite
GpsStatus
Location
LocationManager
LocationProvider
com.google.android.maps包下有這些類：
All Classes
GeoPoint
ItemizedOverlay
ItemizedOverlay.OnFocusChangeListener
MapActivity
MapController
MapView
MapView.LayoutParams
MapView.ReticleDrawMode
MyLocationOverlay
Overlay
Overlay.Snappable
OverlayItem
Projection
TrackballGestureDetector
我們邊看代碼邊熟悉這些類。

 

要獲取當前位置坐標，就是從Location對象中獲取latitude和longitude屬性。那Location對象是如何創建的？
LocationManager locMan=(LocationManager)getSystemService(Context.LOCATION_SERVICE);//LocationManager對象只能這麼創建，不能用new
Location location=locMan.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if(location==null){
    location=locMan.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
}
//注意要為應用程序添加使用權限

<uses-permissionandroid:name="android.permission.ACCESS_FINE_LOCATION"/> 
所謂getLastKnownLocation自然是獲取最新的地理位置信息，那LocationManager.GPS_PROVIDER和LocationManager.NETWORK_PROVIDER有什麼區別呢？俺也不是學通信的，對這個不了解，在網上看到有人想“在室外有GPS定位，在室內想用Wifi或基站定位”。
除了直接使用LocationManager提供的靜態Provider（如GPS_PROVIDER和NETWORK_PROVIDER等）外，還可以使用我們自己創建的LocationProvider對象。
創建LocationProvider對象一般要先創建Criteria對象，來設置我們的LocationProvider要滿足什麼樣的標准
Criteria myCri=new Criteria();
myCri.setAccuracy(Criteria.ACCURACY_FINE);//精確度
myCri.setAltitudeRequired(false);//海拔不需要
myCri.setBearingRequired(false);//Bearing是“軸承”的意思，此處可理解為地軸線之類的東西，總之Bearing Information是一種地理位置信息的描述
myCri.setCostAllowed(true);//允許產生現金消費
myCri.setPowerRequirement(Criteria.POWER_LOW);//耗電
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翻譯為“最適合的"
Location location=locMan.getLastKnownLoation(myProvider);
double latitude=location.getLatitude();//獲取緯度
double longitude=location.getLongitude();//獲取經度

我想知道當前位置描述（比如“武漢華中科技大學”而不是一個經緯值）呢？這就要使用GeoCoder創建一個Address對象了。
Geocoder gc=new Geocoder(context,Locale.CHINA);//Locale是java.util中的一個類
List<Address> listAddress=gc.getFromLocation(latitude,longitude,1);
List<Address>     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.(返回給定經緯值附近的一個Address）

既然是“附近”那實際編碼時我們沒必要把經緯值給的那麼精確，而取一個近似的整數，像這樣：

/*自經緯度取得地址，可能有多行地址*/

List<Address> listAddress=gc.getFromLocation((int)latitude,(int)longitude,1);

StringBuilder sb=new StringBuilder();

/*判斷是不否為多行*/
if(listAddress.size()>0){
    Address address=listAddress.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");

}

public int getMaxAddressLineIndex ()

Since: API Level 1

Returns 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 1

Returns 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.

 

反過來我們可以輸入地址信息獲取經緯值

Geocoder  mygeoCoder=new Geocoder(myClass.this,Locale.getDefault());

List<Address> lstAddress=mygeoCoder.getFromLocationName(strAddress,1);　　　　//strAddress是輸入的地址信息

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<Address> 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

locationName a user-supplied description of a location
maxResults
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

IllegalArgumentException if locationName is null
IOException
if the network is unavailable or any other I/O problem occurs

 

說了半天還只是個定位，地圖還沒出來。下面要用到com.google.android.maps包了

下面的代碼我們讓地圖移到指定點

GeoPoint p=new GeoPoint((int)(latitude*1E6),(int)(longitude*1E6));

MapView mapview=(MapView)findViewById(R.id.mv);

MapController mapContr=mapview.getController();

mapview.displayZoomControls(true);//顯示地圖縮放的按鈕

mapContr.animateTo(p);//帶動畫移到p點

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:




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.

在地圖上指定一點給出經緯值

@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().

 

如果需要我們還可以把經緯值轉換成手機的屏幕坐標值

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;

放大縮小地圖主要就是用setZoom(int ZoomLevel)函數,讓ZoomLevel不停往上漲（或往下降）就可以了

下面給出一個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 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. 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.
  原文來自:博客園（華夏35度）http://www.cnblogs.com/zhangchaoyang 作者:Orisun