android location 位置定位

实现功能：定位当前位置并显示详细信息，扩展了googleMap地图

package com.ld.gps;

import java.util.List;
import java.util.Locale;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
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.provider.Settings;
import android.widget.TextView;
import android.widget.Toast;

public class AppLocationGpsActivity extends Activity {

	private static final int TWO_MINUTES = 1000 * 60 * 2;
	private LocationManager locationManager;

	private String providerName;

	private Location currentBestLocation;

	private Location location;
	
	private Address address;

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		// 获取 LocationManager 服务

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

		// 获取 Location Provider

		providerName=getProviderName();

		// 如果未设置位置源，打开 GPS 设置界面

		openGPS();

		// 获取位置

		currentBestLocation= locationManager.getLastKnownLocation(providerName);
		
		location=new Location(LocationManager.GPS_PROVIDER);
		
		if(isBetterLocation(location,currentBestLocation)){
			// 显示位置信息到文字标签

			updateWithNewLocation(location);
			providerName=location.getProvider();

		}else{
			// 显示位置信息到文字标签

			updateWithNewLocation(currentBestLocation);

		}
			
		
		// 注册监听器 locationListener ，第 2 、 3 个参数可以控制接收 gps 消息的频度以节省电力。第 2 个参数为毫秒，

		// 表示调用 listener 的周期，第 3 个参数为米 , 表示位置移动指定距离后就调用 listener

		locationManager.requestLocationUpdates(providerName, 2000, 10,locationListener);
	}

	// 判断是否开启 GPS ，若未开启，打开 GPS 设置界面

	private void openGPS() {

		if (locationManager
				.isProviderEnabled(android.location.LocationManager.GPS_PROVIDER)

				|| locationManager
						.isProviderEnabled(android.location.LocationManager.NETWORK_PROVIDER)

		) {

			Toast.makeText(this, " 位置源已设置！ ", Toast.LENGTH_SHORT).show();

			return;

		}

		Toast.makeText(this, " 位置源未设置！ ", Toast.LENGTH_SHORT).show();

		// 转至 GPS 设置界面

		Intent intent = new Intent(Settings.ACTION_SECURITY_SETTINGS);

		startActivityForResult(intent, 0);

	}

	// 获取 Location Provider

	private String getProviderName() {

		// 构建位置查询条件

		Criteria criteria = new Criteria();

		// 查询精度：高

		criteria.setAccuracy(Criteria.ACCURACY_FINE);

		// 是否查询海拨：否

		criteria.setAltitudeRequired(false);

		// 是否查询方位角 : 否

		criteria.setBearingRequired(false);

		// 是否允许付费：是

		criteria.setCostAllowed(true);

		// 电量要求：低

		criteria.setPowerRequirement(Criteria.POWER_LOW);

		// 返回最合适的符合条件的 provider ，第 2 个参数为 true 说明 , 如果只有一个 provider 是有效的 , 则返回当前
		// provider

		return locationManager.getBestProvider(criteria, true);

	}

	// Gps 消息监听器

	private final LocationListener locationListener = new LocationListener() {

		// 位置发生改变后调用

		public void onLocationChanged(Location location) {

			updateWithNewLocation(location);

		}

		// provider 被用户关闭后调用

		public void onProviderDisabled(String provider) {

			updateWithNewLocation(null);

		}

		// provider 被用户开启后调用

		public void onProviderEnabled(String provider) {
		}

		// provider 状态变化时调用

		public void onStatusChanged(String provider, int status,

		Bundle extras) {
		}

	};

	// Gps 监听器调用，处理位置信息

	private void updateWithNewLocation(Location location) {

		String latLongString;

		TextView myLocationText = (TextView) findViewById(R.id.text);

		if (location != null) {

			double lat = location.getLatitude();

			double lng = location.getLongitude();

			latLongString = " 纬度 :" + lat + "\n 经度 :" + lng;

		} else {

			latLongString = " 无法获取地理信息 ";

		}
		List<Address> addrList=getAddressbyGeoPoint(location);
		String addr="当前详细地址：";
		if(addrList!=null && !addrList.isEmpty())
			addr+=parseAddr(addrList.get(0));
		myLocationText.setText(" 您当前的位置是 :\n" +

		latLongString + "\n" + addr);

	}

	private String parseAddr(Address address){
		
		return address.getAddressLine(0)+address.getAddressLine(1)+address.getAddressLine(2)+address.getFeatureName();
	}
	// 获取地址信息

	private List<Address> getAddressbyGeoPoint(Location location) {

		List<Address> result = null;

		// 先将 Location 转换为 GeoPoint

		// GeoPoint gp =getGeoByLocation(location);

		try {

			if (location != null) {

				// 获取 Geocoder ，通过 Geocoder 就可以拿到地址信息

				Geocoder gc = new Geocoder(this, Locale.getDefault());

				result = gc.getFromLocation(location.getLatitude(),
						location.getLongitude(), 1);

			}

		} catch (Exception e) {

			e.printStackTrace();

		}

		return result;

	}

	/**
	 * Determines whether one Location reading is better than the current
	 * Location fix
	 * 
	 * @param location
	 *            The new Location that you want to evaluate
	 * @param currentBestLocation
	 *            The current Location fix, to which you want to compare the new
	 *            one
	 */
	protected boolean isBetterLocation(Location location,
			Location currentBestLocation) {
		if (currentBestLocation == null) {
			// A new location is always better than no location
			return true;
		}

		// Check whether the new location fix is newer or older
		long timeDelta = location.getTime() - currentBestLocation.getTime();
		boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
		boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES;
		boolean isNewer = timeDelta > 0;

		// If it's been more than two minutes since the current location, use
		// the new location
		// because the user has likely moved
		if (isSignificantlyNewer) {
			return true;
			// If the new location is more than two minutes older, it must be
			// worse
		} else if (isSignificantlyOlder) {
			return false;
		}

		// Check whether the new location fix is more or less accurate
		int accuracyDelta = (int) (location.getAccuracy() - currentBestLocation
				.getAccuracy());
		boolean isLessAccurate = accuracyDelta > 0;
		boolean isMoreAccurate = accuracyDelta < 0;
		boolean isSignificantlyLessAccurate = accuracyDelta > 200;

		// Check if the old and new location are from the same provider
		boolean isFromSameProvider = isSameProvider(location.getProvider(),
				currentBestLocation.getProvider());

		// Determine location quality using a combination of timeliness and
		// accuracy
		if (isMoreAccurate) {
			return true;
		} else if (isNewer && !isLessAccurate) {
			return true;
		} else if (isNewer && !isSignificantlyLessAccurate
				&& isFromSameProvider) {
			return true;
		}
		return false;
	}

	/** Checks whether two providers are the same */
	private boolean isSameProvider(String provider1, String provider2) {
		if (provider1 == null) {
			return provider2 == null;
		}
		return provider1.equals(provider2);
	}
}