Android 位置管理器(LocationManager)

Android LocationManager的提供了一系列与地理位置相关的服务，包括允许应用获取设备的周期性的位置更新；以及接近某个地理位置坐标时触发一个已定义Intent的等。只需要进行一些简单的设置，你的应用程序就可以接受位置更新，在这次教程里你将详细的学习这些步骤。
在Manifest里声明相关的权限
要想获取位置更新，第一步需要在manifest里声明合适的权限。如果忘了声明相应的权限，那么你的应用在运行时会报安全异常。当你使用LocationManagement方法的时候，需要设置权限ACCESS_CORASE_LOCATION或者 ACCESS_FINE_LOCATION，例如，如果你的应用使用了基于网络的信息服务，你需要声明ACCESS_CORASE_LOATION权限，要想获取GPS请求你需要声明ACCESS_FINE_LOCATION权限。值得注意的是如果你声明了ACCESS_FINE_LOCATION权限隐含着你也声明了ACCESS_CORASE_LOCATION权限。

假如一个应用使用了基于网络的位置的信息服务，你需要声明因特网权限。

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>    <uses-permission android:name="android.permission.INTERNET"/>

获得一个位置管理的引用

LocationManager是Android系统提供的一项服务。使用方法类似于其他的服务，通过调用getSystemService方法可以获得相应的引用。

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

选择一个位置提供者
当没有请求的时候，现在大部分android电源管理可以通过多种底层技术可以获得位置更新，这种技术被抽象为LocationProvider类的应用。在时间、精度、成本、电源消耗等方面，位置提供者有不同的运行特性。通常，GPS位置提供者定位精确度高，花费时间长，基于网络的位置提供者定位精确度低，但是花费时间比较短。

通过权衡之后你必须选择一种特殊的位置提供者，或者多重提供者，这些都依赖与你的应用的客户需求。例如，比如说一个关键点的签到服务，需要高精度定位，而一个零售商店定位器使用城市级别的修正就可以满足。下面的代码段要求一个GPS提供者的支持。

LocationProvider provider = locationManager.getProvider(LocationManager.GPS_PROVIDER);

你可以提供一些输入标准，比如精度、功率需求、成本等等，让android决定一个最合适的位置匹配提供者。下边的代码片段需要的是更精确的位置提供者而不是考虑成本。需要注意的是这个标准不能帮你解决任何的提供者，可能返回值为空。这个时候你的应用应该能够很好的处理这种情况：

// Retrieve a list of location providers that have fine accuracy, no monetary cost, etcCriteria criteria = new Criteria();criteria.setAccuracy(Criteria.ACCURACY_FINE);criteria.setCostAllowed(false);//criteria.setPowerRequirement(Criteria.POWER_MEDIUM);//criteria.setBearingAccuracy(Criteria.ACCURACY_LOW);String providerName = locationManager.getBestProvider(criteria, true);// If no suitable provider is found, null is returned.if (providerName != null) {   Log.i(TAG, "BestProvider name:"+providerName);}

检查位置提供者是否启用
在设置里，一些位置提供者比如GPS可以被关闭。良好的做法就是通过调用isProviderEnabled()方法来检测你想要的位置提供者是否打开。如果位置提供者被关闭了，你可以在设置里通过启动Intent来让用户打开。

@Overrideprotected void onStart() {boolean gpsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);if (!gpsEnabled) {        // Build an alert dialog here that requests that the user enable        // the location services, then when the user clicks the "OK" button,        // call enableLocationSettings()    }super.onStart();}private void enableLocationSettings() {    Intent settingsIntent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);    startActivity(settingsIntent);}

获取周期性位置更新

通过LocationManager requestLocationUpdates(String provider, long minTime, float minDistance, LocationListener listener)获取周期性位置更新。

/** * determines location using satellites. Depending on conditions, this provider may take a while to return a location fix.  * Requires the permission android.Manifest.permission.ACCESS_FINE_LOCATION.  */private void requestLocationByGPS() {locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 0, mLocationListener);Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);  if(location!=null){double lat = location.getLatitude();     //经度  double lng = location.getLongitude(); //纬度  double altitude =  location.getAltitude();     //海拔  Log.i(TAG, "LastKnownLocation latitude="+lat+",longitude="+lng+",altitude="+altitude);}}private LocationListener mLocationListener = new LocationListener() {@Overridepublic void onStatusChanged(String provider, int status, Bundle extras) {// TODO Auto-generated method stub}@Overridepublic void onProviderEnabled(String provider) {// TODO Auto-generated method stub}@Overridepublic void onProviderDisabled(String provider) {// TODO Auto-generated method stub}@Overridepublic void onLocationChanged(Location location) {if(location==null){return;}double lat = location.getLatitude();     //经度  double lng = location.getLongitude(); //纬度  double altitude =  location.getAltitude();     //海拔  Log.e(TAG, "onLocationChanged lat="+lat+",lng="+lng+",altitude="+altitude);}};

停止更新

通过LocationManager removeUpdates(LocationListener listener)方法来停止更新。

locationManager.removeUpdates(mLocationListener);

最后附上完整示例代码：

package com.example.gpsdemo;import android.app.Activity;import android.content.Context;import android.content.Intent;import android.location.Criteria;import android.location.Location;import android.location.LocationListener;import android.location.LocationManager;import android.os.Bundle;import android.provider.Settings;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends Activity implements OnClickListener {private static final String TAG = MainActivity.class.getSimpleName();private Button bt_gps;private Button bt_network;private Button bt_stop;private LocationManager locationManager;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);findViewById();setListener();processLogic();}private void processLogic() {locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);// Retrieve a list of location providers that have fine accuracy, no monetary cost, etcCriteria criteria = new Criteria();criteria.setAccuracy(Criteria.ACCURACY_FINE);criteria.setCostAllowed(false);//criteria.setPowerRequirement(Criteria.POWER_MEDIUM);//criteria.setBearingAccuracy(Criteria.ACCURACY_LOW);String providerName = locationManager.getBestProvider(criteria, true);// If no suitable provider is found, null is returned.if (providerName != null) {   Log.i(TAG, "BestProvider name:"+providerName);}}private void findViewById() {bt_gps = (Button) findViewById(R.id.bt_gps);bt_network = (Button) findViewById(R.id.bt_network);bt_stop = (Button) findViewById(R.id.bt_stop);}private void setListener() {bt_gps.setOnClickListener(this);bt_network.setOnClickListener(this);bt_stop.setOnClickListener(this);}@Overridepublic void onClick(View v) {switch (v.getId()) {case R.id.bt_gps:requestLocationByGPS();break;case R.id.bt_network:requestLocationByNetwork();break;case R.id.bt_stop://Removes all location updates for the specified LocationListener.locationManager.removeUpdates(mLocationListener);break;default:break;}}@Overrideprotected void onStart() {boolean gpsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);if (!gpsEnabled) {        // Build an alert dialog here that requests that the user enable        // the location services, then when the user clicks the "OK" button,        // call enableLocationSettings()    }super.onStart();}private void enableLocationSettings() {    Intent settingsIntent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);    startActivity(settingsIntent);}/** *  determines location based on availability of cell tower and WiFi access points.  *  Requires the permission android.Manifest.permission.INTERNET  */private void requestLocationByNetwork() {locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 1000, 0, mLocationListener);Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);  if(location!=null){double lat = location.getLatitude();     //经度  double lng = location.getLongitude(); //纬度  double altitude =  location.getAltitude();     //海拔  Log.i(TAG, "LastKnownLocation latitude="+lat+",longitude="+lng+",altitude="+altitude);}}/** * determines location using satellites. Depending on conditions, this provider may take a while to return a location fix.  * Requires the permission android.Manifest.permission.ACCESS_FINE_LOCATION.  */private void requestLocationByGPS() {locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 0, mLocationListener);Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);  if(location!=null){double lat = location.getLatitude();     //经度  double lng = location.getLongitude(); //纬度  double altitude =  location.getAltitude();     //海拔  Log.i(TAG, "LastKnownLocation latitude="+lat+",longitude="+lng+",altitude="+altitude);}}private LocationListener mLocationListener = new LocationListener() {@Overridepublic void onStatusChanged(String provider, int status, Bundle extras) {// TODO Auto-generated method stub}@Overridepublic void onProviderEnabled(String provider) {// TODO Auto-generated method stub}@Overridepublic void onProviderDisabled(String provider) {// TODO Auto-generated method stub}@Overridepublic void onLocationChanged(Location location) {if(location==null){return;}double lat = location.getLatitude();     //经度  double lng = location.getLongitude(); //纬度  double altitude =  location.getAltitude();     //海拔  Log.e(TAG, "onLocationChanged lat="+lat+",lng="+lng+",altitude="+altitude);}};@Overrideprotected void onStop() {Log.i(TAG, "onStop");locationManager.removeUpdates(mLocationListener);super.onStop();}}

关于LocationManager的详细介绍可以参考Developer文档：http://developer.android.com/reference/android/location/LocationManager.html