如何在黑莓中获取当前位置的纬度和经度?

问题描述

我正在开发一个具有 GPS 功能的应用程序.如何获取当前位置的经纬度.

I am developing an app which has GPS functionality. How can I get latitude and longitude of the current location.

推荐答案

我自己找到了解决方案.以下代码对我来说很好用:

I found a solution by myself. The following code works fine for me:

package mypackage;

import javax.microedition.location.Location;
import javax.microedition.location.LocationException;
import javax.microedition.location.LocationListener;
import javax.microedition.location.LocationProvider;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.Dialog;
import net.rim.device.api.ui.component.RichTextField;
import net.rim.device.api.ui.container.MainScreen;

public final class MyScreen extends MainScreen
{
    private LocationProvider locationProvider;
    private static int interval = 1;
    double lat;
    double longt;

    public MyScreen()
    {
        setTitle("MyTitle");
        startLocationUpdate();
    }

    private boolean startLocationUpdate()
    {
        boolean retval = false;

        try
        {
            locationProvider = LocationProvider.getInstance(null);

            if ( locationProvider == null )
            {
                Runnable showGpsUnsupportedDialog = new Runnable()
                {
                    public void run()
                    {
                        Dialog.alert("GPS is not supported on this platform, exiting...");
                        //System.exit( 1 );
                    }
                };

                UiApplication.getUiApplication().invokeAndWait( showGpsUnsupportedDialog ); // Ask event-dispatcher thread to display dialog ASAP.
            }
            else
            {
                locationProvider.setLocationListener(new LocationListenerImpl(), interval, 1, 1);

                retval = true;
            }
        }
        catch (LocationException le)
        {
            System.err.println("Failed to instantiate the LocationProvider object, exiting...");
            System.err.println(le);
            System.exit(0);
        }
        return retval;
    }

    private class LocationListenerImpl implements LocationListener
    {
        public void locationUpdated(LocationProvider provider, Location location)
        {
            if(location.isValid())
            {
                double longitude = location.getQualifiedCoordinates().getLongitude();
                double latitude = location.getQualifiedCoordinates().getLatitude();

                updateLocationScreen(latitude, longitude);
            }
        }

        public void providerStateChanged(LocationProvider provider, int newState)
        {
        }
    }

    private void updateLocationScreen(final double latitude, final double longitude)
    {
        UiApplication.getUiApplication().invokeAndWait(new Runnable()
        {
            public void run()
            {
                lat = latitude;
                longt = longitude;

                RichTextField txt=new RichTextField();
                txt.setText("Long=="+longt);

                RichTextField txt1=new RichTextField();
                txt1.setText("lat=="+lat);

                add(txt);
                add(txt1);
                //persistentLatitude.setContents(Double.toString(latitude));
                //persistentLongitude.setContents(Double.toString(longitude));
            }
        });
    }
}

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