如何使这个定位器(GPS)在android上工作

Question

我做了一个查找位置应用程序，在textview中显示纬度和经度。下面是我的代码:

package com.application.geocoding;
import android.app.Activity;
import android.os.Bundle;
import android.content.Context;
import android.location.Location;
import android.location.LocationManager;
import android.widget.TextView;
public class main extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        LocationManager locationManager;
        String context = Context.LOCATION_SERVICE;
        locationManager = (LocationManager)getSystemService(context);
        String provider = LocationManager.GPS_PROVIDER;
        Location location = 
          locationManager.getLastKnownLocation(provider);
        updateWithNewLocation(location);
    }
    private void updateWithNewLocation(Location location) {
        String latLongString;
        TextView myLocationText; 
        myLocationText=(TextView)findViewById(R.id.textView1);
        if (location != null) {
          double lat = location.getLatitude();
          double lng = location.getLongitude();
          latLongString = "Lat:" + lat + "nLong:" + lng;
        } else {
          latLongString = "No location found"; 
        }
        myLocationText.setText("Your Current Position is:n" + 
                               latLongString);
    }
}

这是舱单:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.application.geocoding"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".main"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

代码仍然不工作，只能显示"No location found" textview..有人知道如何解决这个问题吗?谢谢. .

Answer 1

你可以这样做:

LocationListener myLocationListener = new LocationListener() {
            public void onLocationChanged(Location location) {
            String latLongString;
                 TextView myLocationText; 
                 myLocationText=(TextView)findViewById(R.id.textView1);
                 double lat = location.getLatitude();
                 double lng = location.getLongitude();
                 latLongString = "Lat:" + lat + "nLong:" + lng;
                 myLocationText.setText("Your Current Position is:n" + 
                           latLongString);
}   
        }
        public void onProviderDisabled(String provider) {
        }
        public void onProviderEnabled(String provider) {
        }
        public void onStatusChanged(String provider, int status,
                Bundle extras) {
        }
    };
    int t = 5000; // millisekunder
    int dist = 5; // meter
    locationManager.requestLocationUpdates(provider, t, dist, myLocationListener);

Answer 2

从你的活动开始，它将获得GPS坐标，但在那个时候，如果你没有从DDMS发送GPS坐标，那么它将返回null

这个只会给你一个时间值如果你想获得gps的持续值你需要为它定义一个监听器比如LocationListener

参见教程链接

http://developer.android.com/guide/topics/location/obtaining-user-location.html

http://www.firstdroid.com/2010/04/29/android-development-using-gps-to-get-current-location-2/

http://www.androidcompetencycenter.com/?s=GPS

Answer 3

您是否尝试过实现LocationListener并重写onLocationChanged(Location loc) ?另外，您是否正在使用模拟器?编辑:你可以在这里找到一个例子。

Answer 4

您实际上并没有调用GPS位置获取，而是请求最后一个。如果它从未被调用过，它将始终返回null。

更好的方法是在onResume()中注册LocationListener，并通过locationManager.requestLocattionUpdates()和locationManager.removeUpdates()在onPause()中取消注册。