Cách lấy mã quốc gia hiện tại từ Network Provider Android

Giới thiệu

Hướng dẫn này trình bày cách lấy mã quốc gia (country code - ISO 3166-1 alpha-2) của vị trí hiện tại sử dụng Network Provider và Geocoder trên Android.

Các bước thực hiện

Bước 1: Tạo dự án mới

Tạo dự án Android Studio: File → New Project.

Bước 2: Layout activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
    xmlns:app="https://schemas.android.com/apk/res-auto"
    xmlns:tools="https://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:gravity="center"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/text"
        android:textSize="30sp"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

Bước 3: MainActivity.java

package com.example.myapplication;

import android.Manifest;
import android.content.pm.PackageManager;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationManager;
import android.os.Build;
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import android.widget.TextView;
import java.io.IOException;
import java.util.List;
import java.util.Locale;

public class MainActivity extends AppCompatActivity {

    TextView textView;
    Location location;
    Geocoder geocoder;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = findViewById(R.id.text);

        LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
        
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) 
                != PackageManager.PERMISSION_GRANTED 
                && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) 
                != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, 
                new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION}, 101);
            return;
        }

        location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
        geocoder = new Geocoder(this, Locale.getDefault());
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == 101) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                updateCountryCode();
            }
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) 
                == PackageManager.PERMISSION_GRANTED 
                || ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) 
                == PackageManager.PERMISSION_GRANTED) {
            updateCountryCode();
        }
    }

    private void updateCountryCode() {
        if (location == null) {
            textView.setText("Không lấy được vị trí từ Network Provider");
            return;
        }
        
        try {
            List
 addresses = geocoder.getFromLocation(
                location.getLatitude(), location.getLongitude(), 1);
            if (addresses != null && !addresses.isEmpty()) {
                Address address = addresses.get(0);
                String countryCode = address.getCountryCode();
                textView.setText("Mã quốc gia: " + (countryCode != null ? countryCode : "Không xác định"));
            } else {
                textView.setText("Không tìm thấy địa chỉ từ vị trí này");
            }
        } catch (IOException e) {
            e.printStackTrace();
            textView.setText("Lỗi Geocoder: " + e.getMessage());
        }
    }
}

Bước 4: AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="https://schemas.android.com/apk/res/android"
    package="com.example.myapplication">

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity android:name=".MainActivity">
            <intent-filter>
                

TelephonyManager telephonyManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE) 
        == PackageManager.PERMISSION_GRANTED) {
    String networkOperator = telephonyManager.getNetworkOperator(); // Ví dụ: "45202"
    if (networkOperator != null && networkOperator.length() >= 3) {
        String mcc = networkOperator.substring(0, 3); // "452" - Việt Nam
        String mnc = networkOperator.substring(3);    // "02" - Viettel
    }
}