在Android中获取位置更新 [英] Getting location Updates in Android
问题描述
您好，请使用以下用于此处的代码:如何在Android中获取当前位置这里使用TextView一次显示位置坐标.现在，一旦位置不断变化，如何在TextView中保持更新位置.
Hi AM using the code below used here : How to get current location in Android Here am using the TextView to display the location coordinates once. Now How can I keep update the location in TextView once the location keeps changing.
我现在正在使用的代码:这是我的主要活动
Codes i'm using now: This is my main Activity
package com.example.locationtests;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
GPSTracker mGPS = new GPSTracker(this);
TextView text = (TextView) findViewById(R.id.texts);
if(mGPS.canGetLocation ){
mGPS.getLocation();
text.setText("Lat"+mGPS.getLatitude()+"Lon"+mGPS.getLongitude());
}else{
text.setText("Unabletofind");
System.out.println("Unable");
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
This is the class im using for Tracking:
package com.example.locationtests;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.provider.Settings;
import android.util.Log;
public final class GPSTracker implements LocationListener {
private final Context mContext;
// flag for GPS status
public boolean isGPSEnabled = false;
// flag for network status
boolean isNetworkEnabled = false;
// flag for GPS status
boolean canGetLocation = false;
Location location; // location
double latitude; // latitude
double longitude; // longitude
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 1; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1; // 1 minute
// Declaring a Location Manager
protected LocationManager locationManager;
public GPSTracker(Context context) {
this.mContext = context;
getLocation();
}
/**
* Function to get the user's current location
*
* @return
*/
public Location getLocation() {
try {
locationManager = (LocationManager) mContext
.getSystemService(Context.LOCATION_SERVICE);
// getting GPS status
isGPSEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
Log.v("isGPSEnabled", "=" + isGPSEnabled);
// getting network status
isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
Log.v("isNetworkEnabled", "=" + isNetworkEnabled);
if (isGPSEnabled == false && isNetworkEnabled == false) {
// no network provider is enabled
} else {
this.canGetLocation = true;
if (isNetworkEnabled) {
location=null;
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {
location=null;
if (location == null) {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return location;
}
/**
* Stop using GPS listener Calling this function will stop using GPS in your
* app
* */
public void stopUsingGPS() {
if (locationManager != null) {
locationManager.removeUpdates(GPSTracker.this);
}
}
/**
* Function to get latitude
* */
public double getLatitude() {
if (location != null) {
latitude = location.getLatitude();
}
// return latitude
return latitude;
}
/**
* Function to get longitude
* */
public double getLongitude() {
if (location != null) {
longitude = location.getLongitude();
}
// return longitude
return longitude;
}
/**
* Function to check GPS/wifi enabled
*
* @return boolean
* */
public boolean canGetLocation() {
return this.canGetLocation;
}
/**
* Function to show settings alert dialog On pressing Settings button will
* lauch Settings Options
* */
public void showSettingsAlert() {
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
// Setting Dialog Title
alertDialog.setTitle("GPS is settings");
// Setting Dialog Message
alertDialog
.setMessage("GPS is not enabled. Do you want to go to settings menu?");
// On pressing Settings button
alertDialog.setPositiveButton("Settings",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Intent intent = new Intent(
Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
}
});
// on pressing cancel button
alertDialog.setNegativeButton("Cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
// Showing Alert Message
alertDialog.show();
}
@Override
public void onLocationChanged(Location location) {
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
}
This is my AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.locationtests"
android:versionCode="1"
android:versionName="1.0" >
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.location" android:required="true" />
<uses-feature android:name="android.hardware.location.gps" android:required="false" />
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.locationtests.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
推荐答案
当您在locationManger上调用requestRequestUpdates方法时，请将"this"指定为LocationListener:
When you call the method requestLocationUpdates on locationManger, you specify 'this' as the LocationListener:
locationManager.requestLocationUpdates(..., ..., ..., this);
这很好，因为该类实现了LocationListener.位置更改时进行的回调是方法"onLocationChanged".您的班级中有这个方法，但是它没有代码，所以什么也没做:
That's fine since the class implements LocationListener. The callback made when the location changes is the method 'onLocationChanged'. You have this method in your class but it has no code so does nothing:
@Override
public void onLocationChanged(Location location) {
}
添加适当的代码，以从"location"参数获取新的纬度和经度，并在活动"中更新TextView.有很多方法可以做到这一点.我想到两个:
Add appropriate code to get the new Latitude and Longitude from the 'location' parameter and update the TextView back in your Activity. There are a number of ways to do that. Two that come to mind:
1)将引用传递给GPSTracker类构造函数中的TextView，以便您可以从类中访问它.2)在GPSTracker类构造函数中传递对Activity的引用，以便您可以在Activity中调用一个方法(该方法接受要显示的值)，然后可以更新TextView.
1) Pass a reference to the TextView in the GPSTracker class constructor so you can access it from the class. 2) Pass a reference to the Activity in the GPSTracker class constructor so you can call a method in your Activity (that accepts the values to show) that can then update the TextView.
您已经有了我在上面第2点中提到的参考.当您在活动"中实例化GPSTracker实例时，您已经将其传递为"this":
You already have the reference I refer to in point 2 above. When you instantiate your instance of GPSTracker in your Activity, you already pass it 'this':
GPSTracker mGPS = new GPSTracker(this);
在这种情况下，"this"是MainActivity类的实例，而Activity类也恰好是一个Context.在GPSTracker的构造函数中，您将此上下文存储在变量中:
In this case 'this' is the instance of your MainActivity class and an Activity class also happens to be a Context. In the constructor of GPSTracker you are storing this context in a variable:
public GPSTracker(Context context) {
this.mContext = context;
因此，您可以使用它来访问TextView.将您需要的上下文强制转换为一个Activity，然后可以在其上使用findViewById方法:
You can therefore use it to access the TextView. Cast the context you have to an Activity and you can then use the findViewById method on it:
@Override
public void onLocationChanged(Location location)
{
TextView text = (TextView) ((Activity)mContext).findViewById(R.id.texts);
text.setText("Lat"+location.getLatitude()+"Lon"+location.getLongitude());
}
这篇关于在Android中获取位置更新的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
