我在后台线程中使用异步任务上传图片来显示进度对话框。但是从异步任务获取位置时,会引发以下错误:
java.lang.RuntimeException:无法在线程内创建处理程序 没有调用Looper.prepare()
虽然没有异步任务就可以工作。我希望在后台线程中完成定位的过程,以便主线程可以无干扰地工作。
从异步任务调用时,locationmanager.requestLocationUpdates()
的GPSlocater.java出错了。
那我该怎么办?
这是onLocate函数,它从mainActivity.java调用
public void onLocate(View view) {
asyncG asyncG1 = new asyncG(this);
asyncG1.execute();
}
这是在mainActivity.java中创建的子类
class asyncG extends AsyncTask
{
Context context;
ProgressDialog progressDialog;
public asyncG(MainActivity mainActivity) {
this.context = mainActivity;
}
@Override
protected Object doInBackground(Object[] objects) {
GPSlocater gpSlocater = new GPSlocater(context);
gpSlocater.getLocation();
lat = gpSlocater.getLatitude();
longi = gpSlocater.getLongitude();
return null;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog = new ProgressDialog(context);
progressDialog.setMessage("Finding Location");
progressDialog.show();
}
@Override
protected void onPostExecute(Object o) {
super.onPostExecute(o);
progressDialog.dismiss();
Geocoder geocoder = new Geocoder(context, Locale.getDefault());
try {
List<Address> arr;
arr = geocoder.getFromLocation(lat,longi,1);
String pincode = arr.get(0).getPostalCode();
String stat = arr.get(0).getAdminArea();
String city1 = arr.get(0).getLocality();
String city2 = arr.get(0).getSubAdminArea();
String area1 = arr.get(0).getSubLocality();
String area2 = arr.get(0).getLocality();
if(pincode!=null && stat!=null)
{
state.setText(stat);
pin.setText(pincode);
}
if(city1!=null)
{
city.setText(city1);
}
else if(city2!=null)
{
city.setText(city2);
}
if(area1!=null)
{
area.setText(area1);
}
else if(area2!=null)
{
area.setText(area2);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
这是从doInBackground
package com.example.samarth.serviceprovider1;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.app.Service;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;
import android.util.Log;
public class GPSlocater extends Service implements LocationListener {
private final Context mContext;
// flag for GPS status
boolean isGPSEnabled = false;
// flag for network status
boolean isNetworkEnabled = false;
// flag for GPS status
boolean canGetLocation = false;
Location location; // location
double latitude; // latitude
double longitude; // longitude
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute
// Declaring a Location Manager
protected LocationManager locationManager;
public GPSlocater(Context context) {
this.mContext = context;
}
public Location getLocation() {
try {
locationManager = (LocationManager) mContext
.getSystemService(LOCATION_SERVICE);
// getting GPS status
isGPSEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
// getting network status
isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isGPSEnabled && !isNetworkEnabled) {
// no network provider is enabled
showSettingsAlert();
} else {
this.canGetLocation = true;
// First get location from Network Provider
if (isNetworkEnabled) {
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {
if (location == null) {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return location;
}
/**
* Stop using GPS listener
* Calling this function will stop using GPS in your app
* */
public void stopUsingGPS(){
if(locationManager != null){
locationManager.removeUpdates(GPSlocater.this);
}
}
/**
* Function to get latitude
* */
public double getLatitude(){
if(location != null){
latitude = location.getLatitude();
}
// return latitude
return latitude;
}
/**
* Function to get longitude
* */
public double getLongitude(){
if(location != null){
longitude = location.getLongitude();
}
// return longitude
return longitude;
}
/**
* Function to check GPS/wifi enabled
* @return boolean
* */
public boolean canGetLocation() {
return this.canGetLocation;
}
/**
* Function to show settings alert dialog
* On pressing Settings button will lauch Settings Options
* */
public void showSettingsAlert(){
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
// Setting Dialog Title
alertDialog.setTitle("GPS is settings");
// Setting Dialog Message
alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");
// On pressing Settings button
alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
}
});
// on pressing cancel button
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
// Showing Alert Message
alertDialog.show();
}
@Override
public void onLocationChanged(Location location) {
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public IBinder onBind(Intent arg0) {
return null;
}
}
答案 0 :(得分:0)
您需要创建一个处理程序来访问线程中的UI元素。 https://developer.android.com/training/multiple-threads/communicate-ui.html 本教程应该让你顺利,祝你好运(: