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Android GPS, บทช่วยสอนเกี่ยวกับตัวจัดการตำแหน่ง


ตัวอย่างนี้สาธิตวิธีการเข้าถึง Android GPS, โปรแกรมจัดการตำแหน่ง

ขั้นตอนที่ 1 − สร้างโครงการใหม่ใน Android Studio ไปที่ไฟล์ ⇒ โครงการใหม่และกรอกรายละเอียดที่จำเป็นทั้งหมดเพื่อสร้างโครงการใหม่

ขั้นตอนที่ 2 − เพิ่มรหัสต่อไปนี้ใน res/layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
   xmlns:tools="https://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:gravity="center_horizontal"
   android:orientation="vertical"
   tools:context=".MainActivity">
<Button
   android:id="@+id/btn_start_location_updates"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="40dp"
   android:onClick="startLocationButtonClick"
   android:text="@string/start_updates" />
<Button
   android:id="@+id/btn_stop_location_updates"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="10dp"
   android:enabled="false"
   android:onClick="stopLocationButtonClick"
   android:text="@string/stop_updates" />
<Button
   android:id="@+id/btn_get_last_location"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="10dp"
   android:onClick="showLastKnownLocation"
   android:text="@string/get_last_location" />
<TextView
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="50dp"
   android:gravity="center_horizontal"
   android:text="Location updates will be received only when app is foreground" />
<TextView
   android:id="@+id/location_result"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="20dp"
   android:textColor="#333"
   android:textSize="18sp" />
<TextView
   android:id="@+id/updated_on"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="30dp"
   android:textSize="12sp" />
</LinearLayout>

ขั้นตอนที่ 3 − เพิ่มรหัสต่อไปนี้ใน src/MainActivity.java

package app.com.sample;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import android.Manifest;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.content.IntentSender;
import android.content.pm.PackageManager;
import android.location.Location;
import android.net.Uri;
import android.os.Bundle;
import android.os.Looper;
import android.provider.Settings;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.common.api.ApiException;
import com.google.android.gms.common.api.ResolvableApiException;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationCallback;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationResult;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.location.LocationSettingsRequest;
import com.google.android.gms.location.LocationSettingsResponse;
import com.google.android.gms.location.LocationSettingsStatusCodes;
import com.google.android.gms.location.SettingsClient;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.karumi.dexter.Dexter;
import com.karumi.dexter.PermissionToken;
import com.karumi.dexter.listener.PermissionDeniedResponse;
import com.karumi.dexter.listener.PermissionGrantedResponse;
import com.karumi.dexter.listener.PermissionRequest;
import com.karumi.dexter.listener.single.PermissionListener;
import java.text.DateFormat;
import java.util.Date;
public class MainActivity extends AppCompatActivity {
   private static final String TAG = MainActivity.class.getSimpleName();
   TextView txtLocationResult;
   TextView txtUpdatedOn;
   Button btnStartUpdates;
   Button btnStopUpdates;
   // location last updated time
   private String mLastUpdateTime;
   // location updates interval - 10sec
   private static final long UPDATE_INTERVAL_IN_MILLISECONDS = 10000;
   // fastest updates interval - 5 sec
   // location updates will be received if another app is requesting the locations
   // than your app can handle
   private static final long FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS = 5000;
   private static final int REQUEST_CHECK_SETTINGS = 100;
   // bunch of location related apis
   private FusedLocationProviderClient mFusedLocationClient;
   private SettingsClient mSettingsClient;
   private LocationRequest mLocationRequest;
   private LocationSettingsRequest mLocationSettingsRequest;
   private LocationCallback mLocationCallback;
   private Location mCurrentLocation;
   // boolean flag to toggle the ui
   private Boolean mRequestingLocationUpdates;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      // initialize the necessary libraries
      init();
      // restore the values from saved instance state
      restoreValuesFromBundle(savedInstanceState);
   }
   private void init() {
      txtLocationResult = findViewById(R.id.location_result);
      txtUpdatedOn = findViewById(R.id.updated_on);
      btnStartUpdates = findViewById(R.id.btn_start_location_updates);
      btnStopUpdates = findViewById(R.id.btn_stop_location_updates);
      mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
      mSettingsClient = LocationServices.getSettingsClient(this);
      mLocationCallback = new LocationCallback() {
         @Override
         public void onLocationResult(LocationResult locationResult) {
            super.onLocationResult(locationResult);
            // location is received
            mCurrentLocation = locationResult.getLastLocation();
            mLastUpdateTime = DateFormat.getTimeInstance().format(new Date());
            updateLocationUI();
         }
      };
      mRequestingLocationUpdates = false;
      mLocationRequest = new LocationRequest();
      mLocationRequest.setInterval(UPDATE_INTERVAL_IN_MILLISECONDS);
      mLocationRequest.setFastestInterval(FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS);
      mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
      LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder();
      builder.addLocationRequest(mLocationRequest);
      mLocationSettingsRequest = builder.build();
   }
/**
* Restoring values from saved instance state
*/
   private void restoreValuesFromBundle(Bundle savedInstanceState) {
      if (savedInstanceState != null) {
         if (savedInstanceState.containsKey("is_requesting_updates")) {
            mRequestingLocationUpdates = savedInstanceState.getBoolean("is_requesting_updates");
         }
         if (savedInstanceState.containsKey("last_known_location")) {
            mCurrentLocation = savedInstanceState.getParcelable("last_known_location");
         }
         if (savedInstanceState.containsKey("last_updated_on")) {
            mLastUpdateTime = savedInstanceState.getString("last_updated_on");
         }
      }
      updateLocationUI();
   }
/**
* Update the UI displaying the location data
* and toggling the buttons
*/
   private void updateLocationUI() {
      if (mCurrentLocation != null) {
         txtLocationResult.setText(
         "Lat: " + mCurrentLocation.getLatitude() + ", " +
         "Lng: " + mCurrentLocation.getLongitude()
         );
         // giving a blink animation on TextView
         txtLocationResult.setAlpha(0);
         txtLocationResult.animate().alpha(1).setDuration(300);
         // location last updated time
         txtUpdatedOn.setText("Last updated on: " + mLastUpdateTime);
      }
      toggleButtons();
   }
   @Override
   public void onSaveInstanceState(Bundle outState) {
      super.onSaveInstanceState(outState);
      outState.putBoolean("is_requesting_updates", mRequestingLocationUpdates);
      outState.putParcelable("last_known_location", mCurrentLocation);
      outState.putString("last_updated_on", mLastUpdateTime);
   }
   private void toggleButtons() {
      if (mRequestingLocationUpdates) {
         btnStartUpdates.setEnabled(false);
         btnStopUpdates.setEnabled(true);
      }
       else {
         btnStartUpdates.setEnabled(true);
         btnStopUpdates.setEnabled(false);
      }
   }
/**
* Starting location updates
* Check whether location settings are satisfied and then
* location updates will be requested
*/
   private void startLocationUpdates() {
      mSettingsClient
      .checkLocationSettings(mLocationSettingsRequest)
      .addOnSuccessListener(this, new OnSuccessListener() {
         @SuppressLint("MissingPermission")
         @Override
         public void onSuccess(LocationSettingsResponse locationSettingsResponse) {
         Log.i(TAG, "All location settings are satisfied.");
         Toast.makeText(getApplicationContext(), "Started location updates!",
         Toast.LENGTH_SHORT).show();
         //noinspection MissingPermission
         mFusedLocationClient.requestLocationUpdates(mLocationRequest,
         mLocationCallback, Looper.myLooper());
         updateLocationUI();
      }
   })
   .addOnFailureListener(this, new OnFailureListener() {
      @Override
      public void onFailure(@NonNull Exception e) {
         int statusCode = ((ApiException) e).getStatusCode();
            switch (statusCode) {
               case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
               Log.i(TAG, "Location settings are not satisfied. Attempting to upgrade " + "location settings ");
               try {
                  // Show the dialog by calling startResolutionForResult(), and check the
                  // result in onActivityResult().
                  ResolvableApiException rae = (ResolvableApiException) e;
                  rae.startResolutionForResult(MainActivity.this, REQUEST_CHECK_SETTINGS);
               }
               catch (IntentSender.SendIntentException sie) {
                  Log.i(TAG, "PendingIntent unable to execute request.");
               }
               break;
               case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
               String errorMessage = "Location settings are inadequate, and cannot be " + "fixed here. Fix in Settings.";
               Log.e(TAG, errorMessage);
               Toast.makeText(MainActivity.this, errorMessage, Toast.LENGTH_LONG).show();
            }
            updateLocationUI();
         }
      });
   }
   public void startLocationButtonClick(View view) {
      // Requesting ACCESS_FINE_LOCATION using Dexter library
      Dexter.withActivity(this)
      .withPermission(Manifest.permission.ACCESS_FINE_LOCATION)
      .withListener(new PermissionListener() {
         @Override
         public void onPermissionGranted(PermissionGrantedResponse response) {
            mRequestingLocationUpdates = true;
            startLocationUpdates();
         }
         @Override
         public void onPermissionDenied(PermissionDeniedResponse response) {
            if (response.isPermanentlyDenied()) {
               // open device settings when the permission is
               // denied permanently
               openSettings();
            }
         }
         @Override
         public void onPermissionRationaleShouldBeShown(PermissionRequest permission,
         PermissionToken token) {
            token.continuePermissionRequest();
         }
      }).check();
   }
   public void stopLocationButtonClick(View view) {
      mRequestingLocationUpdates = false;
      stopLocationUpdates();
   }
   public void stopLocationUpdates() {
      // Removing location updates
      mFusedLocationClient
      .removeLocationUpdates(mLocationCallback)
      .addOnCompleteListener(this, new OnCompleteListener() {
         @Override
         public void onComplete(@NonNull Task task) {
            Toast.makeText(getApplicationContext(), "Location updates stopped!",
            Toast.LENGTH_SHORT).show();
            toggleButtons();
         }
      });
   }
   public void showLastKnownLocation(View view) {
      if (mCurrentLocation != null) {
         Toast.makeText(getApplicationContext(), "Lat: " + mCurrentLocation.getLatitude() + ", Lng: " + mCurrentLocation.getLongitude(), Toast.LENGTH_LONG).show();
      }
       else {
         Toast.makeText(getApplicationContext(), "Last known location is not available!",
         Toast.LENGTH_SHORT).show();
      }
   }
   @Override
   protected void onActivityResult(int requestCode, int resultCode, Intent data) {
      // Check for the integer request code originally supplied to startResolutionForResult().
      if (requestCode == REQUEST_CHECK_SETTINGS) {
         switch (resultCode) {
            case Activity.RESULT_OK:
            Log.e(TAG, "User agreed to make required location settings changes.");
            // Nothing to do. startLocationupdates() gets called in onResume again.
               break;
               case Activity.RESULT_CANCELED:
               Log.e(TAG, "User chose not to make required location settings changes.");
               mRequestingLocationUpdates = false;
               break;
            }
         }
      }
      private void openSettings() {
         Intent intent = new Intent();
         intent.setAction(
         Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
         Uri uri = Uri.fromParts("package",
         BuildConfig.APPLICATION_ID, null);
         intent.setData(uri);
         intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
         startActivity(intent);
      }
      @Override
      public void onResume() {
         super.onResume();
         // Resuming location updates depending on button state and
         // allowed permissions
         if (mRequestingLocationUpdates && checkPermissions()) {
            startLocationUpdates();
         }
         updateLocationUI();
      }
      private boolean checkPermissions() {
         int permissionState = ActivityCompat.checkSelfPermission(this,
         Manifest.permission.ACCESS_FINE_LOCATION);
         return permissionState == PackageManager.PERMISSION_GRANTED;
      }
      @Override
      protected void onPause() {
         super.onPause();
         if (mRequestingLocationUpdates) {
            // pausing location updates
            stopLocationUpdates();
         }
      }
   }

ขั้นตอนที่ 4 − เพิ่มรหัสต่อไปนี้ใน androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="https://schemas.android.com/apk/res/android"
   package="app.com.sample">
   <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
      <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>
               <action android:name="android.intent.action.MAIN" />
               <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

มาลองเรียกใช้แอปพลิเคชันของคุณกัน ฉันคิดว่าคุณได้เชื่อมต่ออุปกรณ์มือถือ Android จริงกับคอมพิวเตอร์ของคุณ ในการรันแอพจาก android studio ให้เปิดไฟล์กิจกรรมของโปรเจ็กต์แล้วคลิกไอคอน Run จากแถบเครื่องมือ เลือกอุปกรณ์มือถือของคุณเป็นตัวเลือก แล้วตรวจสอบอุปกรณ์มือถือของคุณซึ่งจะแสดงหน้าจอเริ่มต้นของคุณ -

Android GPS, บทช่วยสอนเกี่ยวกับตัวจัดการตำแหน่ง