android 自带gps定位Location相关知识

android自带gps定位功能相信大家都不会太陌生了，都有所涉及。简单的写了一个示例程序，获取经纬度还有其它相关数据的代码，还有其他相关的知识，比如直接跳转到打开系统gps设置的界面。还有一个bug的处理，异常信息：Incomplete location object, missing timestamp or accuracy

1、获取location 示例程序

package com.example.locationexample;import android.location.Location;import android.location.LocationListener;import android.location.LocationManager;import android.os.Build;import android.os.Bundle;import android.os.SystemClock;import android.util.Log;import android.widget.TextView;import android.annotation.TargetApi;import android.app.Activity;import android.content.Context;public class MainActivity extends Activity {LocationManager mLocationManager;Location mlocation;TextView mTextView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mTextView = (TextView)findViewById(R.id.textView1);getLocation();//mlocation.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());//mLocationManager.setTestProviderLocation(LocationManager.GPS_PROVIDER, mlocation);}public Location getLocation(){mLocationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);mlocation = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);if (mlocation == null) {mlocation = mLocationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);}mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 100, 0, mLocationListener);return mlocation;}LocationListener mLocationListener = new LocationListener() {@TargetApi(17)@Overridepublic void onLocationChanged(Location mlocal) {if(mlocal == null) return;String strResult = "getAccuracy:" + mlocal.getAccuracy() + "\r\n"+ "getAltitude:" + mlocal.getAltitude() + "\r\n"+ "getBearing:" + mlocal.getBearing() + "\r\n"+ "getElapsedRealtimeNanos:" + String.valueOf(mlocal.getElapsedRealtimeNanos()) + "\r\n"+ "getLatitude:" + mlocal.getLatitude() + "\r\n"+ "getLongitude:" + mlocal.getLongitude() + "\r\n"+ "getProvider:" + mlocal.getProvider()+ "\r\n"+ "getSpeed:" + mlocal.getSpeed() + "\r\n"+ "getTime:" + mlocal.getTime() + "\r\n";Log.i("Show", strResult);if (mTextView != null) {mTextView.setText(strResult);}}@Overridepublic void onProviderDisabled(String arg0) {}@Overridepublic void onProviderEnabled(String arg0) {}@Overridepublic void onStatusChanged(String provider, int event, Bundle extras) {}};}

在这里提醒一下，最好activity销毁时候onDestroy()，移除mLocationManager这个变量。

权限如下：

还有重点看这行代码参数mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 100, 0, mLocationListener);

LocationManager.GPS_PROVIDER是gps提供，100是时间，多久刷新一次，0是距离，如果你不动的话，测试最好写0

mLocationListener是接口啦，数据就是那里来的。

2、异常

如果你使用mLocationManager.setTestProviderLocation(LocationManager.GPS_PROVIDER, mlocation);这行代码报出下面的堆栈错误信息

 java.lang.IllegalArgumentException: Incomplete location object, missing timestamp or accuracy? Location[gps 23.126704,113.365648 acc=1 et=?!? alt=-7.422 vel=0.008333334 bear=237.76]

解决办法：

方法一：
主要是这句，location.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());，其实加上这句就可以了。

例如：

    @SuppressLint("NewApi")    private Location getLoc(String provider)    {        Location location = new Location(provider);        location.setLatitude(lat);        location.setLongitude(lng);        location.setAltitude(altitude);        location.setBearing(bearing);        location.setSpeed(speed);        location.setAccuracy(accuracy);        location.setTime(System.currentTimeMillis());        location.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());        return location;    }

主要是这句，location.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());，其实加上这句就可以了。如下

mlocation.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());mLocationManager.setTestProviderLocation(LocationManager.GPS_PROVIDER, mlocation);

方法二，加上下面的反射调用：

    try    {        Method method = Location.class.getMethod("makeComplete");        if (method != null)        {            method.invoke(localLocation);        }    }    catch (NoSuchMethodException e)    {        e.printStackTrace();    }    catch (Exception e)    {        e.printStackTrace();    }

方法二使用，是借鉴android系统源码的反射作用

源码如下：

   /**     * Helper to fill incomplete fields.     *     * Used to assist in backwards compatibility with     * Location objects received from applications.     *     * @see #isComplete     * @hide     */    public void makeComplete() {        if (mProvider == null) mProvider = "?";        if (!mHasAccuracy) {            mHasAccuracy = true;            mAccuracy = 100.0f;        }        if (mTime == 0) mTime = System.currentTimeMillis();        if (mElapsedRealtimeNanos == 0) mElapsedRealtimeNanos = SystemClock.elapsedRealtimeNanos();    }

建议使用第一个方法。

3、是否已打开自身GPS

//获取是否已打开自身GPSpublic boolean isGpsEnable() {String providers = Settings.Secure.getString(mContext.getContentResolver(), Settings.Secure.LOCATION_PROVIDERS_ALLOWED);if (providers.contains(LocationManager.GPS_PROVIDER)) {return true;} else {return false;}}

4、直接跳转到系统设置gps界面

Intent callGPSSettingIntent = new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);this.startActivity(callGPSSettingIntent);

1、获取location 示例程序

2、异常

3、是否已打开自身GPS

4、直接跳转到系统设置gps界面

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