Android获取当前位置,location为空

通过最后一次的地理位置来获得Location对象：location = locationManager.getLastKnownLocation(provider);得出location为空。查看各种资料发现，getLastKnownLocation仅仅是获取当缓存中的上一次打开地图缓存起来的位置，不可能一次就能获取，那唯有location为空的时候继续获取，采用locationManager.requestLocationUpdates("gps",
60000, 1, locationListener); 这样解决了问题，贴出整合修改的代码。

package com.belle.tools;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;

import android.content.Context;
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.util.Log;
import android.widget.Toast;

public class LocationUtils {
public String cityName;
// 此对象能通过经纬度来获取相应的城市等信息
private Geocoder geocoder;
private LocationManager locationManager;
private String provider;
private Location location;
private Context context;
/*
* 通过地理坐标获取城市名 其中CN分别是city和name的首字母缩写
*/
public String getCNBylocation(Context context) {
geocoder = new Geocoder(context);
String serviceName = Context.LOCATION_SERVICE;
// 实例化一个LocationManager对象
locationManager = (LocationManager) context.getSystemService(serviceName);
// provider的类型
// String provider = LocationManager.NETWORK_PROVIDER;
getProvider();
//openGPS();
// 通过最后一次的地理位置来获得Location对象
location = locationManager.getLastKnownLocation(provider);
if(location == null){
locationManager.requestLocationUpdates("gps", 60000, 1, locationListener);
}
String queryed_name = updateWithNewLocation(location);
if ((queryed_name != null) && (0 != queryed_name.length())) {
cityName = queryed_name;
}
/**
* 第二个参数表示更新的周期，单位为毫秒；第三个参数表示最小距离间隔，单位是米 设定每30秒进行一次自动定位
*/
locationManager.requestLocationUpdates(provider, 30000, 50,
locationListener);
return cityName;
}

/**
* 方位改变时触发，进行调用
*/
private final LocationListener locationListener = new LocationListener() {
String tempCityName;

public void onLocationChanged(Location location) {
tempCityName = updateWithNewLocation(location);
if ((tempCityName != null) && (tempCityName.length() != 0)) {
cityName = tempCityName;
}
}

public void onProviderDisabled(String provider) {
tempCityName = updateWithNewLocation(null);
if ((tempCityName != null) && (tempCityName.length() != 0)) {
cityName = tempCityName;
}
}
public void onProviderEnabled(String provider) {
}
public void onStatusChanged(String provider, int status, Bundle extras) {
}
};

/**
* 更新location
*/
private String updateWithNewLocation(Location location1) {
String mcityName = "";
double lat = 0;
double lng = 0;
List<Address> addList = null;
if (location1 != null) {
lat = location1.getLatitude();
lng = location1.getLongitude();
} else {
System.out.println("无法获取地理信息");
}
try {
addList = geocoder.getFromLocation(lat, lng, 1);
} catch (IOException e) {
e.printStackTrace();
}
if (addList != null && addList.size() > 0) {
for (int i = 0; i < addList.size(); i++) {
Address add = addList.get(i);
mcityName += add.getLocality();
}
}
if (mcityName.length() != 0) {
return mcityName.substring(0, (mcityName.length() - 1));
} else {
return mcityName;
}
}

/**
* 通过经纬度获取地址信息的另一种方法
*/
public String GetAddr(String latitude, String longitude) {
String addr = "";
/*
* 也可以是http://maps.google.cn/maps/geo?output=csv&key=abcdef&q=%s,%s，
* 不过解析出来的是英文地址 密钥可以随便写一个key=abc
* output=csv,也可以是xml或json，不过使用csv返回的数据最简洁方便解析
*/
String url = String.format(
"http://maps.google.cn/maps/geo?output=csv&key=abcdef&q=%s,%s",
latitude, longitude);
URL myURL = null;
URLConnection httpsConn = null;
try {
myURL = new URL(url);
} catch (MalformedURLException e) {
e.printStackTrace();
return null;
}
try {
httpsConn = (URLConnection) myURL.openConnection();
if (httpsConn != null) {
InputStreamReader insr = new InputStreamReader(
httpsConn.getInputStream(), "UTF-8");
BufferedReader br = new BufferedReader(insr);
String data = null;
if ((data = br.readLine()) != null) {
String[] retList = data.split(",");
if (retList.length > 2 && ("200".equals(retList[0]))) {
addr = retList[2];
} else {
addr = "";
}
}
insr.close();
}
} catch (IOException e) {
e.printStackTrace();
return null;
}
return addr;
}

private void openGPS() {

if (locationManager.isProviderEnabled(android.location.LocationManager.GPS_PROVIDER)
|| locationManager.isProviderEnabled(android.location.LocationManager.NETWORK_PROVIDER)
){
Toast.makeText(context, " 位置源已设置！ ", Toast.LENGTH_SHORT).show();
return;
}
Toast.makeText(context, " 位置源未设置！", Toast.LENGTH_SHORT).show();
}

private void getProvider() {
// TODO Auto-generated method stub
// 构建位置查询条件
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);  //高精度
criteria.setAltitudeRequired(false);  //不查询海拔
criteria.setBearingRequired(false);  //不查询方位
criteria.setCostAllowed(true);  //不允许付费
criteria.setPowerRequirement(Criteria.POWER_LOW);  //低耗
// 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
provider = locationManager.getBestProvider(criteria, true);
}
}