现在有这么一个需求:开启一个Service服务,获取当前位置的经纬度数据,将获取的数据以广播的方式发送出去,注册广播的Activity接收广播信息,并将接收到的数据在当前Activity显示,如果当前位置发生变化,经纬度数据改变,获取改变后的经纬度数据,通过Handler发送消息,更新UI界面,显示更新后的内容,请问这样子的Demo该如何实现?
LocationTool获取当前位置信息
Android手机获取当前位置的方式:GPS定位,WIFI定位,基站定位,当前Demo使用GPS卫星定位,在LocationTool中返回Location、LocationManager两者对象,通过Location提供的getLatitude()、getLongitude()读取经纬度数据,同时添加位置改变监听器MyLocationListener,具体代码如下:
package cn.teachcourse.utils;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.provider.Settings;
import android.widget.Toast;
public class LocationTool {
public Location getLocation() {
return mLocation;
}
public void setLocation(Location location) {
this.mLocation = location;
}
private Context context;
private Location mLocation;
private LocationManager mLocationManager;
public LocationTool(Context context) {
super();
mLocationManager = (LocationManager) context
.getSystemService(Context.LOCATION_SERVICE);
mLocation = mLocationManager.getLastKnownLocation(getProvider());
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,
2000, 10, new MyLocationListener(this));
}
// 获取Location Provider
private String getProvider() {
// 构建位置查询条件
Criteria criteria = new Criteria();
// 查询精度:高
criteria.setAccuracy(Criteria.ACCURACY_FINE);
// 是否查询海拨:否
criteria.setAltitudeRequired(false);
// 是否查询方位角 : 否
criteria.setBearingRequired(false);
// 是否允许付费:是
criteria.setCostAllowed(true);
// 电量要求:低
criteria.setPowerRequirement(Criteria.POWER_LOW);
// 返回最合适的符合条件的provider,第2个参数为true说明 , 如果只有一个provider是有效的,则返回当前provider
return mLocationManager.getBestProvider(criteria, true);
}
public LocationManager getLocationManager() {
return mLocationManager;
}
private LocationListener mLocationListener = new LocationListener() {
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
Location l = mLocationManager.getLastKnownLocation(provider);
if (l != null) {
mLocation = l;
}
}
@Override
public void onProviderDisabled(String provider) {
mLocation = null;
}
@Override
public void onLocationChanged(Location location) {
if (location != null) {
mLocation = location;
}
}
};
public void closeLocation() {
if (mLocationManager != null) {
if (mLocationManager != null) {
mLocationManager.removeUpdates(mLocationListener);
mLocationListener = null;
}
mLocationManager = null;
}
}
}
MyLocationListener位置改变监听器
LocationManager对象调用requestLocationUpdates(String provider, long minTime, float minDistance,LocationListener listener),在回调的方法中获取改变后的Location对象,其中provider表示LocationManager.GPS_PROVIDER,minTime表示最短时间间隔内更新位置信息(单位毫秒),minDistance表示最短距离内更新位置信息(单位米),MyLocationListener继承LocationListener,需要重写的方法如下:
package cn.teachcourse.utils;
import android.location.Location;
import android.location.LocationListener;
import android.os.Bundle;
public class MyLocationListener implements LocationListener {
private LocationTool gpsTool;
public MyLocationListener(LocationTool gpsTool) {
super();
this.gpsTool = gpsTool;
}
@Override
public void onLocationChanged(Location location) {
if (location != null) {
gpsTool.setLocation(location);
}
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
Location l = gpsTool.getLocationManager()
.getLastKnownLocation(provider);
if (l != null) {
gpsTool.setLocation(l);
}
}
@Override
public void onProviderDisabled(String provider) {
gpsTool.setLocation(null);
}
}
LocationService服务读取位置信息
为什么要开启Service呢?Service和Activity、Fragment一样也有自己的生命周期,onCreate——>onStartCommand(onStart)——>onUnbind——>onRebind——>onDestroy,在LocationService执行的操作是启动一个线程获取更新后的位置信息,并以广播的方式发送出去,具体代码如下:
package cn.teachcourse.utils;
import android.app.Activity;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.location.Location;
import android.location.LocationManager;
import android.os.IBinder;
import android.provider.Settings;
import android.widget.Toast;
public class LocationService extends Service {
private LocationTool mGPSTool = null;
private boolean threadDisable = false;
private final static String TAG = LocationService.class.getSimpleName();
@Override
public void onCreate() {
// TODO Auto-generated method stub
super.onCreate();
mGPSTool = new LocationTool(this);
startThread();
}
private void startThread() {
new Thread(new Runnable() {
@Override
public void run() {
while (!threadDisable) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
if (mGPSTool != null) { // 当结束服务时gps为空
// 获取经纬度
Location location = mGPSTool.getLocation();
// 发送广播
Intent intent = new Intent();
intent.putExtra("lat",
location == null ? "" : location.getLatitude()
+ "");
intent.putExtra("lon",
location == null ? "" : location.getLongitude()
+ "");
intent.setAction("cn.teachcourse.utils.GPSService");
sendBroadcast(intent);
}
}
}
}).start();
}
@Override
public void onDestroy() {
super.onDestroy();
threadDisable = true;
if (mGPSTool != null) {
mGPSTool.closeLocation();
mGPSTool = null;
}
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
}
MainActivity启动服务、注册广播、显示位置信息
在MainActivity需要做的事情有:第一启动LocationService服务,调用startService()方法;第二注册广播接收器(BroadcastReceiver),创建了一个内部类MyBroadcastReceiver,继承BroadcastReceiver,重写onReceive方法;第三获取经纬度数据,更新UI界面,显示当前位置信息,具体代码如下:
//启动服务
startService(new Intent(this, LocationService.class));
//注册广播
private class MyReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
Bundle bundle = intent.getExtras();
String lon = bundle.getString("lon");
String lat = bundle.getString("lat");
if (!TextUtils.isEmpty(lon) && !TextUtils.isEmpty(lat)) {
mLatitude = lat;
mLongitude = lon;
isObtainLoc = true;
new Thread(new Runnable() {
@Override
public void run() {
Message msg = new Message();
msg.what = REFRESH_UI;// 发送消息,通知刷新界面
mHandler.sendMessage(msg);
}
}).start();
}
}
}
//更新UI界面
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
switch (msg.what) {
case REFRESH_UI:
reFreshUI();
break;
default:
break;
}
}
};
private void reFreshUI() {
if (isObtainLoc) {
mTextView.setText("目前经纬度\n经度:" + mLongitude + "\n纬度:" + mLatitude);
mDialog.dismiss();
}
}
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