Android開發中GPS導航獲取位置時的代碼示范

2020-02-21 17:36:46

字體：大中小

來源：轉載

供稿：網友

隨著移動互聯網的發展，越來越多手機支持GPS定位獲取地理位置，Android的開發人員當然也不例外，但是開發中難免會遇到問題，本篇文章描述的是Android開發中GPS導航獲取位置時的代碼示范，武林技術頻道小編帶你進入下文了解！

Android開發中GPS導航獲取位置時的代碼示范

getLastKnownLocation(LocationManager.GPS_PROVIDER),

于是高興地不得了。可是一寫進代碼里，返回值（Location 類型）居然一直為null..郁悶的不得了。在網上查了好久，發現好多人都和我一樣糾結于這個問題上，有人說是因為GPS沒打開，也有人說是相關權限沒加上..可是我的明明已經在設置里打開，權限自然也加上了。在api上糾結了半天，終于找出原因了，原來要打開GPS其實在于這句：
　

　
setTestProviderEnabled("gps",true);

而跟手機上的設置沒多大關系（起碼在我的手機上測是這樣的）。手機上的設置關閉了，這一句照樣能打開；而即使手機設置打開了，沒這一句也是白搭。與這句對應的是
　

　
setTestProviderEnabled("gps",false);

用來關閉GPS.
GPS打開后可以用上面的方法獲取Location了嗎？還是不可以！確切地說是有時候可以，因為這個函數獲取的是上次已經獲得的位置信息，設想如果此程序第一次跑，先前并沒有獲取過位置信息，當然返回值為null了。經仔細查看api，在

requestLocationUpdates (String provider, long minTime, float minDistance, LocationListener listener)

里發現了這樣一句話：It may take a while to receive the most recent location. If an immediate location is required, applications may use the getLastKnownLocation(String) method. 因此為了獲取位置信息，應該用此方法為manager設置監聽器，在監聽器中onLocationChanged(Location location)里獲取。
測試代碼如下：

public void onLocationChanged(Location location)
??????????? {
??????????????? Log.i("onLocationChanged", "come in");
??????????????? if (location != null)
??????????????? {
??????????????????? Log.w("Location","Current altitude = "+ location.getAltitude());
??????????????????? Log.w("Location","Current latitude = "+ location.getLatitude());
??????????????? }
??????????? }
????

經過測試，經過一段時間后可以獲取Location（獲取時間與minTime、minDistance相關）。還需注意的一個問題是在設置了監聽器后，刪除監聽器之前不能用上面的方法關閉gps，否則會報錯。因此關閉gps的方法是
　

　
manager.removeUpdates (listener);//listener 即為監聽器實例
manager.setTestProviderEnabled("gps",false);

以下是測試代碼，所需權限有：

import android.app.Activity;
?import android.content.Context;
?import android.location.Criteria;
?import android.location.Location;
?import android.location.LocationListener;
?import android.location.LocationManager;
?import android.os.Bundle;
?import android.util.Log;
?public class audio extends Activity
?{
???? /** Called when the activity is first created. */
???? LocationManager locationManager;
???? LocationListener llistener;
???? String provider;
???? public void onCreate(Bundle savedInstanceState)
???? {
???????? super.onCreate(savedInstanceState);
???????? setContentView(R.layout.main);
???????? Criteria criteria = new Criteria();
???????? criteria.setAccuracy(Criteria.ACCURACY_FINE);
???????? criteria.setAltitudeRequired(false);
???????? criteria.setBearingRequired(false);
???????? criteria.setCostAllowed(true);
???????? criteria.setPowerRequirement(Criteria.POWER_LOW);
???????? String serviceName = Context.LOCATION_SERVICE;
???????? locationManager = (LocationManager) getSystemService(serviceName);
???????? locationManager.setTestProviderEnabled("gps", true);
???????? provider = locationManager.getBestProvider(criteria, true);
???????? Log.d("provider", provider);
???????? llistener = new LocationListener() {
???????????? @Override
???????????? public void onLocationChanged(Location location)
???????????? {
???????????????? // TODO Auto-generated method stub
???????????????? Log.i("onLocationChanged", "come in");
???????????????? if (location != null)
???????????????? {
???????????????????? Log.w("Location", "Current altitude = "
???????????????????????????? + location.getAltitude());
???????????????????? Log.w("Location", "Current latitude = "
???????????????????????????? + location.getLatitude());
???????????????? }
???????????????? locationManager.removeUpdates(this);
???????????????? locationManager.setTestProviderEnabled(provider, false);
???????????? }
???????????? @Override
???????????? public void onProviderDisabled(String provider)
???????????? {
???????????????? // TODO Auto-generated method stub
???????????????? Log.i("onProviderDisabled", "come in");
???????????? }
???????????? @Override
???????????? public void onProviderEnabled(String provider)
???????????? {
???????????????? // TODO Auto-generated method stub
???????????????? Log.i("onProviderEnabled", "come in");
???????????? }
???????????? @Override
???????????? public void onStatusChanged(String provider, int status,
???????????????????? Bundle extras)
???????????? {
???????????????? // TODO Auto-generated method stub
???????????????? Log.i("onStatusChanged", "come in");
???????????? }
???????? };
????????? locationManager.requestLocationUpdates(provider, 1000, (float) 1000.0, llistener);
???? }
???? protected void onDestroy()
???? {
???????? locationManager.removeUpdates(llistener);
???????? locationManager.setTestProviderEnabled(provider, false);
???????? super.onDestroy();
???? }