Android保证首次获取到的location对象不为空的解决方案

在阅读《第一行代码》和《疯狂android讲义》后，得到的启发式解决方案。如果仅以GPS_PROVIDER获取location对象，那么在onCreate方法中，location一般都会为空，且在室内无法测试。所以有了如下简单的解决方案：

package com.example.locationtest;import android.location.Location;import android.location.LocationListener;import android.location.LocationManager;import android.os.Bundle;import android.support.v7.app.ActionBarActivity;import android.widget.TextView;public class MainActivity extends ActionBarActivity {    LocationManager locationManager;    TextView textView;    Location location;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        textView = (TextView) findViewById(R.id.textView);        locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);        // 获取location对象        location = getBestLocation(locationManager);        updateView(location);        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,                3000, 8, new LocationListener() {                    @Override                    public void onStatusChanged(String provider, int status,                            Bundle extras) {                    }                    @Override                    public void onProviderEnabled(String provider) {                        updateView(locationManager                                .getLastKnownLocation(provider));                    }                    @Override                    public void onProviderDisabled(String provider) {                        updateView(null);                    }                    @Override                    public void onLocationChanged(Location location) {                        location = getBestLocation(locationManager);// 每次都去获取GPS_PROVIDER优先的location对象                        updateView(location);                    }                });    }    private void updateView(Location location) {        if (location != null) {            StringBuffer sb = new StringBuffer();            sb.append("位置信息：\n");            sb.append("经度：" + location.getLongitude() + ", 纬度："                    + location.getLatitude());            textView.setText(sb.toString());        } else {            textView.setText("");        }    }    /**     * 获取location对象，优先以GPS_PROVIDER获取location对象，当以GPS_PROVIDER获取到的locaiton为null时     * ，则以NETWORK_PROVIDER获取location对象，这样可保证在室内开启网络连接的状态下获取到的location对象不为空     *      * @param locationManager     * @return     */    private Location getBestLocation(LocationManager locationManager) {        Location result = null;        if (locationManager != null) {            result = locationManager                    .getLastKnownLocation(LocationManager.GPS_PROVIDER);            if (result != null) {                return result;            } else {                result = locationManager                        .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);                return result;            }        }        return result;    }}

布局文件如下：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.example.locationtest.MainActivity" >    <TextView         android:id="@+id/textView"        android:layout_width="match_parent"        android:layout_height="wrap_content"       /></RelativeLayout>

用到的权限：

 <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/> <uses-permission android:name="android.permission.INTERNET"/>

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