我正在开发一个列出离用户最近的餐馆的应用程序。单击刷新按钮时，它会列出用户当前位置的餐馆。我正在使用位置管理器并仅在活动进入前台（onResume）时才请求更新，以避免持续使用电池。当应用程序进入 onPause() 时，位置更新将停止。当我通过终端传递更新时，它在模拟器上运行良好。
问题：当我实际更改我的位置（比如开车 5 英里）并打开我的应用程序和活动以显示最近的餐馆时，刷新位置需要很长时间（4-5 分钟），然后应用程序继续运行显示上一个位置的餐厅。但是，如果我实际更改我的位置并访问 Google 地图，然后打开我的餐厅应用程序，那么它会立即运行。我已确保 GPS 已打开。我可以做些什么来让位置管理器在我打开我的活动后立即启动并刷新位置？先感谢您！
package com.mortley.android.restaurantsaver;
public class NearbyRestaurantActivity extends ListActivity implements OnClickListener, LocationListener{
private Button refreshButton, searchRestaurants;
ImageButton goToSearch;
private double[] lastKnownLocation;
private EditText locationEditText;
private LocationManager locManager;
private LocationListener locListener;
private boolean gps_enabled = false;
private boolean network_enabled = false;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.nearbyrestaurants);
refreshButton = (Button)findViewById(R.id.reloadButton);
refreshButton.setOnClickListener(this);
searchRestaurants = (Button)findViewById(R.id.searchButton);
searchRestaurants.setOnClickListener(this);
goToSearch = (ImageButton)findViewById(R.id.goLocationButton);
goToSearch.setOnClickListener(this);
locationEditText = (EditText)findViewById(R.id.addressTextBox);
locationEditText.setVisibility(View.GONE);
goToSearch.setVisibility(View.GONE);
locManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);//??
locManager.requestLocationUpdates( LocationManager.GPS_PROVIDER, 1000, 100, this);
//checks network connectivity
boolean checkConnection = isNetworkAvailable();
if(!checkConnection){
Toast.makeText(getApplicationContext(), "Check your Network Connectivity", Toast.LENGTH_LONG).show();
}
if(checkConnection){
//sets current location parameters for the user
lastKnownLocation = RestaurantHelper.getLastKnownLocation(this);
//Log.v("NearbyRestaurantActivity", "This"+this);
RestaurantApplication application = (RestaurantApplication) this.getApplication();
RestaurantAdapter restaurantAdapter = new RestaurantAdapter(this, R.layout.restaurantrow, R.id.label,new ArrayList<RestaurantReference>());
restaurantAdapter.setLastKnownLocation(lastKnownLocation);
//set a global variable for the RestaurantAdapter in the RestaurantApplication class.
application.setRestaurantAdapter(restaurantAdapter);
//Set the adapter first and then update it when the RestaurantHttpAsyncTask makes a web service call.
setListAdapter(restaurantAdapter);
//Make a webservice call in a different thread passing Keyword for URL as a string array.
RestaurantHttpAsyncTask m_progressTask;
String[] keywords = {"", "american", "asian", "italian","mexican"};
//String[] keywords = {"indian"};
m_progressTask = new RestaurantHttpAsyncTask(NearbyRestaurantActivity.this, keywords);
m_progressTask.setRestaurantAdapter(restaurantAdapter);
m_progressTask.execute();
}
}
@Override
public void onClick(View v) {
//Refresh button helps to refresh the restaurant list on location change. Again it makes a call to the webservice using Async Task
if(v.getId() == refreshButton.getId() ){
try {
gps_enabled = locManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
} catch (Exception ex) {
ex.printStackTrace();
}
try {
network_enabled = locManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
} catch (Exception ex) {
ex.printStackTrace();
}
// don't start listeners if no provider is enabled
if (!gps_enabled && !network_enabled) {
Toast.makeText(getApplicationContext(), "Sorry, Location is not determined. Please enable your Network Providers.", Toast.LENGTH_LONG).show();
}
//check network connectivity before refresh
boolean checkConnection = isNetworkAvailable();
if(!checkConnection){
Toast.makeText(getApplicationContext(), "Check your Network Connectivity", Toast.LENGTH_LONG).show();
}
if(checkConnection){
RestaurantApplication application = (RestaurantApplication) this.getApplication();
RestaurantAdapter restaurantAdapter = new RestaurantAdapter(this, R.layout.restaurantrow, R.id.label, new ArrayList<RestaurantReference>());
restaurantAdapter.setLastKnownLocation(lastKnownLocation);
//set a global variable for the RestaurantAdapter in the RestaurantApplication class.
application.setRestaurantAdapter(restaurantAdapter);
//Set the adapter first and then update it when the RestaurantHttpAsyncTask makes a web service call.
setListAdapter(restaurantAdapter);
//Make a webservice call in a different thread passing Keyword for URL as a string array.
RestaurantHttpAsyncTask m_progressTask, m_progressTask1;
String[] keywords = {"", "american", "asian", "italian","mexican", "chinese", "indian"};
//String[] keywords = {"Chinese"};
m_progressTask = new RestaurantHttpAsyncTask(NearbyRestaurantActivity.this, keywords);
m_progressTask.setRestaurantAdapter(restaurantAdapter);
m_progressTask.execute();
}
}
if(v.getId() == goToSearch.getId() ){
Activity child = this;
while(child.getParent() != null){
child = child.getParent();
}
TabGroup1Activity parent = (TabGroup1Activity)getParent();
InputMethodManager imm = (InputMethodManager)getSystemService(
Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(locationEditText.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
//changes ** restaurantAdapter to RestaurantAdapter1 to test & application to application1
RestaurantApplication application1 = (RestaurantApplication) this.getApplication();
RestaurantAdapter restaurantAdapter1 = new RestaurantAdapter(this, R.layout.restaurantrow, R.id.label, new ArrayList<RestaurantReference>());
restaurantAdapter1.setLastKnownLocation(lastKnownLocation);
//set a global variable for the RestaurantAdapter in the RestaurantApplication class.
application1.setRestaurantAdapter(restaurantAdapter1);
//Set the adapter first and then update it when the RestaurantHttpAsyncTask makes a web service call.
setListAdapter(restaurantAdapter1);
//Make a webservice call in a different thread passing Keyword for URL as a string array.
RestaurantHttpAsyncTaskTextSearch m_progressTask, m_progressTask1;
String keywords = locationEditText.getText().toString();
if(keywords.equals("")){
keywords = "Pizza in Palo Alto";
}
keywords = keywords.replaceAll(" ", "%20");
keywords = keywords.replaceAll(",", "%20");
m_progressTask = new RestaurantHttpAsyncTaskTextSearch (NearbyRestaurantActivity.this, keywords);
m_progressTask.setRestaurantAdapter(restaurantAdapter1);
m_progressTask.execute();
locationEditText.setVisibility(View.GONE);
goToSearch.setVisibility(View.GONE);
}
if(v.getId() == searchRestaurants.getId() ){
if(goToSearch.isShown() == true){
goToSearch.setVisibility(View.GONE);
locationEditText.setVisibility(View.GONE);
}
else if(goToSearch.isShown() == false){
//check network connectivity before refresh
boolean checkConnection = isNetworkAvailable();
if(!checkConnection){
Toast.makeText(getApplicationContext(), "Check your Network Connectivity", Toast.LENGTH_LONG).show();
}
if(checkConnection){
goToSearch.setVisibility(View.VISIBLE);
locationEditText.setVisibility(View.VISIBLE);
}
}
}
}
//Method to check network connectivity
public boolean isNetworkAvailable() {
ConnectivityManager connectivityManager
= (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
if (activeNetworkInfo != null && activeNetworkInfo.isConnectedOrConnecting()) {
//Log.d("network", "Network available:true");
return true;
} else {
//Log.d("network", "Network available:false");
return false;
}
}
@Override
protected void onResume() {
super.onResume();
locManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 50, 100, this);
//Log.v("NearbyRestaurantActivity", "In OnResume()");
}
@Override
protected void onPause() {
super.onPause();
locManager.removeUpdates(this);
//Log.v("NearbyRestaurantActivity", "In onPause()");
}
@Override
public void onLocationChanged(Location location) {
// TODO Auto-generated method stub
}
@Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
}
public class RestaurantHelper {
public static double[] getLastKnownLocation(Activity activity){
double lat = 0.0;
double lon = 0.0;
LocationManager lm = (LocationManager) activity.getSystemService(Context.LOCATION_SERVICE);
Location location = lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if(location == null){
lat = 0.0;
lon = 0.0;
}
else{
//Log.v("Latitude", Double.toString(location.getLatitude()));
//Log.v("Longitude", Double.toString(location.getLongitude()));
lat = location.getLatitude();
lon = location.getLongitude();
}
return new double[]{lat,lon};
}
}