GPS开发常用方法和Criteria确定android location providerGPS

GPS常用方法总结 
取得LocationProvider 

 public void getLocationProvider()
   {
     try
     {
       Criteria mCriteria01 = new Criteria();
       mCriteria01.setAccuracy(Criteria.ACCURACY_FINE);
       mCriteria01.setAltitudeRequired(false);
       mCriteria01.setBearingRequired(false);
       mCriteria01.setCostAllowed(true);
       mCriteria01.setPowerRequirement(Criteria.POWER_LOW);
       strLocationProvider =
       mLocationManager01.getBestProvider(mCriteria01, true);

       mLocation01 = mLocationManager01.getLastKnownLocation
       (strLocationProvider);
     }
     catch(Exception e)
     {
       mTextView01.setText(e.toString());
       e.printStackTrace();
     }
   }

获取经纬度，并返回GeoPoint对象 

 private GeoPoint getGeoByLocation(Location location)
   {
     GeoPoint gp = null;
     try
     {
       /* 当Location存在 */
       if (location != null)
       {
         double geoLatitude = location.getLatitude()*1E6;
         double geoLongitude = location.getLongitude()*1E6;
         gp = new GeoPoint((int) geoLatitude, (int) geoLongitude);
       }
     }
     catch(Exception e)
     {
       e.printStackTrace();
     }
     return gp;
   }

将经纬度转换成实际屏幕坐标 

 Point myScreenCoords = new Point();
 GeoPoint tmpGeoPoint = new GeoPoint((int)(mLocation.getLatitude()*1E6),(int)(mLocation.getLongitude()*1E6));
 mapView.getProjection().toPixels(tmpGeoPoint, myScreenCoords);

点击MapView任意一点获得坐标 

 @Override
 public boolean onTouchEvent(MotionEvent ev) {
     int actionType = ev.getAction();
     switch (actionType) {
     case MotionEvent.ACTION_UP:
             Projection proj = mapView.getProjection();
             GeoPoint loc = proj.fromPixels((int)arg0.getX(), (int)arg0.getY());
             String sirina=Double.toString(loc.getLongitudeE6()/1000000);
             String dolzina=Double.toString(loc.getLatitudeE6()/1000000);

     }

     return false;
 }

经纬度改变来刷新地图 

 public void refreshMapView()
 {
   GeoPoint p = new GeoPoint((int)(dLat* 1E6), (int)(dLng* 1E6));
   mMapView01.displayZoomControls(true);
   /* 将Map的中点移至GeoPoint */
   mMapController01.animateTo(p);
   mMapController01.setZoom(intZoomLevel);
 }

根据当前的经纬度，获取相关的一些地址信息 

 /* 创建Geocoder对象 */
         //根据地理环境来确定编码
         //注意这个Locale是java.util.Locale包的类,获取当前系统设定的语言
         Geocoder gc = new Geocoder
         (EX09_05.this, Locale.getDefault());

         /* 取出地理坐标经纬度 */
         double geoLatitude = (int)gp.getLatitudeE6()/1E6;
         double geoLongitude = (int)gp.getLongitudeE6()/1E6;

         /* 自经纬度取得地址（可能有多行地址） */
         List<Address> lstAddress =
         gc.getFromLocation(geoLatitude, geoLongitude, 1);

         StringBuilder sb = new StringBuilder();

         /* 判断地址是否为多行 */
         if (lstAddress.size() > 0)
         {
           Address adsLocation = lstAddress.get(0);

           for(int i=0;i<adsLocation.getMaxAddressLineIndex();i++)
           {
             sb.append(adsLocation.getAddressLine(i)).append("\n");
           }
           sb.append(adsLocation.getLocality()).append("\n");
           sb.append(adsLocation.getPostalCode()).append("\n");
           sb.append(adsLocation.getCountryName());
         }

根据输入地址，取得其GeoPoint对象 

 private GeoPoint getGeoByAddress(String strSearchAddress)
 {
   GeoPoint gp = null;
   try
   {
     if(strSearchAddress!="")
     {
       Geocoder mGeocoder01 = new Geocoder
       (EX09_07.this, Locale.getDefault());

       List<Address> lstAddress = mGeocoder01.getFromLocationName
                          (strSearchAddress, 1);
       if (!lstAddress.isEmpty())
       {
         Address adsLocation = lstAddress.get(0);
         double geoLatitude = adsLocation.getLatitude()*1E6;
         double geoLongitude = adsLocation.getLongitude()*1E6;
         gp = new GeoPoint((int) geoLatitude, (int) geoLongitude);
       }
     }
   }
   catch (Exception e)
   {
     e.printStackTrace();
   }
   return gp;
 }

地图放大缩小按钮 

 /* 放大Map的Button */
    mButton02 = (Button)findViewById(R.id.myButton2);
    mButton02.setOnClickListener(new Button.OnClickListener()
    {

      public void onClick(View v)
      {
        intZoomLevel++;
        if(intZoomLevel>mMapView01.getMaxZoomLevel())
        {
          intZoomLevel = mMapView01.getMaxZoomLevel();
        }
        mMapController01.setZoom(intZoomLevel);
      }
    });

    /* 缩小Map的Button */
    mButton03 = (Button)findViewById(R.id.myButton3);
    mButton03.setOnClickListener(new Button.OnClickListener()
    {

      public void onClick(View v)
      {
        intZoomLevel--;
        if(intZoomLevel<1)
        {
          intZoomLevel = 1;
        }
        mMapController01.setZoom(intZoomLevel);
      }
    });

android location provider有两个： 

    * LocationManager.GPS_PROVIDER：GPS，精度比较高，但是慢而且消耗电力，而且可能因为天气原因或者障碍物而无法获取卫星信息，另外设备可能没有GPS模块； 
    * LocationManager.NETWORK_PROVIDER：通过网络获取定位信息，精度低，耗电少，获取信息速度较快，不依赖GPS模块。 

为了程序的通用性，希望动态选择location provider。对android通过Location API显示地址信息做了个别改动，可以看到使用了gps定位，精度较高： 

 

这里使用到了Criteria，可根据当前设备情况自动选择哪种location provider。见 

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

 Criteria criteria = new Criteria();
 criteria.setAccuracy(Criteria.ACCURACY_FINE);// 设置为最大精度
 criteria.setAltitudeRequired(false);//不要求海拔信息
 criteria.setBearingRequired(false);// 不要求方位信息
 criteria.setCostAllowed(true);//是否允许付费
 criteria.setPowerRequirement(Criteria.POWER_LOW);// 对电量的要求

 location = locationManager
         .getLastKnownLocation(locationManager.getBestProvider(criteria, true));

原来的写法很简单：

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

 location=locationManager.getLastKnownLocation(LocationManager.NETWORK