Usage examples of GPS positioning in Android

GPS positioning is a function that many mobile phones currently have, and it is very practical. This article describes the usage of GPS positioning in Android with examples. Share it with everyone for your reference. The specific method is as follows:

Generally, to obtain the current location through GPS in Android, you must first obtain a LocationManager instance, and obtain the first location through the getLastKnownLocation() method of the instance. The description of this method is as follows:

void android.location.LocationManager.requestLocationUpdates(String provider, long minTime, float minDistance, LocationListener listener)

provider is the positioning method, which can use GPS positioning (LocationManager.GPS_PROVIDER) or network positioning (LocationManager.NETWORK_PROVIDER). This article is about GPS positioning, so LocationManager.GPS_PROVIDER is used. minTime is the interval between location updates. Listener is a listener for location changes. Define a LocationListener() yourself, override onLocationChanged(), and add actions when the location changes.

The layout file is as follows:

<LinearLayout 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:orientation="vertical"
  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=".MainActivity" >
  
  <TextView
    android:id="@+id/txt_time"
    style="@style/my_text"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="时间:" />
  
  <TextView
    android:id="@+id/txt_lat"
    style="@style/my_text"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="经度:" />
  
  <TextView
    android:id="@+id/txt_lng"
    style="@style/my_text"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="纬度:" />
  
</LinearLayout>

MainActivity.java file is as follows:

package com.hzhi.my_gps;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.content.Context;
import android.view.Menu;
import android.widget.TextView;
public class MainActivity extends Activity {
    
  TextView txt_time;
  TextView txt_lat;
  TextView txt_lng;
  LocationManager lom;
  Location loc;
  Double lat;
  Double lng;
  SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
  Date now;
  String str_date;
  Timer timer;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
      
    get_con();
    get_gps();
      
    timer = new Timer(true);
    timer.schedule(task, 0, 1000);
  }
  
  @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;
  }
    
  public void get_gps(){
      
    lom = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    loc = lom.getLastKnownLocation(LocationManager.GPS_PROVIDER);
      
    if (loc != null) {
      lat = loc.getLatitude();
      lng = loc.getLongitude();
      txt_lat.setText("纬度:" + String.valueOf(lat));
      txt_lng.setText("经度:" + String.valueOf(lng));
    }
    else{
      txt_lat.setText("纬度:未知" );
      txt_lng.setText("经度:未知" );
    }
      
    Criteria criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_FINE);
    criteria.setAltitudeRequired(false);
    criteria.setBearingRequired(false);
    criteria.setCostAllowed(true);
    criteria.setPowerRequirement(Criteria.POWER_LOW);
    String provider = lom.getBestProvider(criteria, true);
      
    lom.requestLocationUpdates(provider, 1000, 10, los);
  }
    
  LocationListener los = new LocationListener(){
    public void onLocationChanged(Location location){
      if (location != null) {
        lat = location.getLatitude();
        lng = location.getLongitude();
        txt_lat.setText("纬度:" + String.valueOf(lat));
        txt_lng.setText("经度:" + String.valueOf(lng));
      }
      else{
        txt_lat.setText("纬度:未知" );
        txt_lng.setText("经度:未知" );
      }
    };
      
    public void onProviderDisabled(String provider){
      
    };
      
    public void onProviderEnabled(String provider){ };
      
    public void onStatusChanged(String provider, int status,
    Bundle extras){ };
  };
    
  // 获取控件
  public void get_con(){
      
    txt_time = (TextView) findViewById(R.id.txt_time);
    txt_lat = (TextView) findViewById(R.id.txt_lat);
    txt_lng = (TextView) findViewById(R.id.txt_lng);
  }
    
  Handler handler = new Handler(){
      
    public void handleMessage(Message msg){
      switch (msg.what){
      case 1:
        get_time();
        break;
      }
    }
  };
    
  TimerTask task = new TimerTask(){ 
     public void run() { 
       Message message = new Message();   
       message.what = 1;   
       handler.sendMessage(message);  
    } 
  };
    
  // 获取时间
  public void get_time(){
      
    now = new Date(System.currentTimeMillis());
    str_date = formatter.format(now);
    txt_time.setText("时间:" + str_date);
  }
}

Add permissions to the AndroidManifest.xml file:

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

Turn on the GPS satellite before running. The running result is as shown in the figure below:

Readers can try it outdoors where there is sufficient signal. It is possible. Get GPS location.

I hope this article will be helpful to everyone’s Android programming design.

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