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法律研究使用 Kotlin 在 Android 上获取用户当前位置的最简单方法？
此示例演示了如何使用 Kotlin 在 Android 上获取用户当前位置。
步骤 1 − 在 Android Studio 中创建一个新项目，转到文件 ⇒ 新建项目，并填写所有必需的详细信息以创建新项目。
在 Gradle 中添加以下依赖项
implementation 'com.google.android.gms:play-services-location:17.0.0'
步骤 2 − 将以下代码添加到 res/layout/activity_main.xml 中。
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout 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:padding="4dp" tools:context=".MainActivity"> <TextView android:id="@+id/text" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_marginTop="70dp" android:background="#008080" android:padding="5dp" android:text="TutorialsPoint" android:textColor="#fff" android:textSize="24sp" android:textStyle="bold" /> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_below="@+id/text" android:layout_centerHorizontal="true" android:layout_marginTop="40dp" android:text="Get Current Location and City Name" android:textAlignment="center" android:textColor="@android:color/holo_orange_dark" android:textSize="24sp" android:textStyle="bold" /> <TextView android:id="@+id/textView" android:textColor="@android:color/background_dark" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerInParent="true" android:textSize="16sp" android:textStyle="bold" /> </RelativeLayout>
步骤 3 − 将以下代码添加到 src/MainActivity.kt 中
import android.Manifest
import android.content.Intent
import android.content.pm.PackageManager
import android.location.Geocoder
import android.location.Location
import android.os.Bundle
import android.os.Handler
import android.os.ResultReceiver
import android.util.Log
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import com.google.android.gms.location.*
class MainActivity : AppCompatActivity() {
private lateinit var fusedLocationClient: FusedLocationProviderClient
private val locationPermissionCode = 2
private lateinit var addressResultReceiver: LocationAddressResultReceiver
private lateinit var currentAddTv: TextView
private lateinit var currentLocation: Location
private lateinit var locationCallback: LocationCallback
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
title = "KotlinApp"
addressResultReceiver = LocationAddressResultReceiver(Handler())
currentAddTv = findViewById(R.id.textView)
fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
locationCallback = object : LocationCallback() {
override fun onLocationResult(locationResult: LocationResult) {
currentLocation = locationResult.locations[0]
getAddress()
}
}
startLocationUpdates()
}
private fun startLocationUpdates() {
if ((ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED)) {
ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.ACCESS_FINE_LOCATION),
locationPermissionCode)
}
else {
val locationRequest = LocationRequest()
locationRequest.interval = 2000
locationRequest.fastestInterval = 1000
locationRequest.priority = LocationRequest.PRIORITY_HIGH_ACCURACY
fusedLocationClient.requestLocationUpdates(locationRequest, locationCallback, null)
}
}
private fun getAddress() {
if (!Geocoder.isPresent()) {
Toast.makeText(this@MainActivity, "Can't find current address, ", Toast.LENGTH_SHORT).show()
return
}
val intent = Intent(this, GetAddressIntentService::class.java)
intent.putExtra("add_receiver", addressResultReceiver)
intent.putExtra("add_location", currentLocation)
startService(intent)
}
override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
if (requestCode == locationPermissionCode) {
if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Toast.makeText(this, "Permission Granted", Toast.LENGTH_SHORT).show()
startLocationUpdates()
}
else {
Toast.makeText(this, "Permission Denied", Toast.LENGTH_SHORT).show()
}
}
}
private inner class LocationAddressResultReceiver(handler: Handler) : ResultReceiver(handler) {
override fun onReceiveResult(resultCode: Int, resultData: Bundle) {
if (resultCode == 0) {
Log.d("Address", "Location null retrying")
getAddress()
}
if (resultCode == 1) {
Toast.makeText(this@MainActivity, "Address not found, ", Toast.LENGTH_SHORT).show()
}
val currentAdd = resultData.getString("address_result")
if (currentAdd != null) {
showResults(currentAdd)
}
}
}
private fun showResults(currentAdd: String) {
currentAddTv.text = currentAdd
}
override fun onResume() {
super.onResume()
startLocationUpdates()
}
override fun onPause() {
super.onPause()
fusedLocationClient.removeLocationUpdates(locationCallback)
}
}步骤 4 − 创建一个新的 Kotlin 类 GetAddressFromIntentService.kt 并添加以下代码
import android.app.IntentService
import android.content.Intent
import android.location.Address
import android.location.Geocoder
import android.location.Location
import android.os.Bundle
import android.os.ResultReceiver
import android.util.Log
import java.util.*
class GetAddressIntentService : IntentService(IDENTIFIER) {
private var addressResultReceiver: ResultReceiver? = null
override fun onHandleIntent(intent: Intent?) {
val msg: String
addressResultReceiver = Objects.requireNonNull(intent)!!.getParcelableExtra("add_receiver")
if (addressResultReceiver == null) {
Log.e("GetAddressIntentService", "No receiver, not processing the request further")
return
}
val location = intent!!.getParcelableExtra<Location>("add_location")
if (location == null) {
msg = "No location, can't go further without location"
sendResultsToReceiver(0, msg)
return
}
val geoCoder = Geocoder(this, Locale.getDefault())
var addresses: List<Address>? = null
try {
addresses = geoCoder.getFromLocation(location.latitude, location.longitude, 1)
}
catch (ioException: Exception) {
Log.e("", "Error in getting address for the location")
}
if (addresses == null || addresses.isEmpty()) {
msg = "No address found for the location"
sendResultsToReceiver(1, msg)
}
else {
val address = addresses[0]
val addressDetails = """
${address.featureName}
${address.thoroughfare}
Locality: ${address.locality}
County: ${address.subAdminArea}
State: ${address.adminArea}
Country: ${address.countryName}
Postal Code: ${address.postalCode}
""".trimIndent()
sendResultsToReceiver(2, addressDetails)
}
}
private fun sendResultsToReceiver(resultCode: Int, message: String) {
val bundle = Bundle()
bundle.putString("address_result", message)
addressResultReceiver!!.send(resultCode, bundle)
}
companion object {
private const val IDENTIFIER = "GetAddressIntentService"
}
}
步骤 5 − 将以下代码添加到 androidManifest.xml 中
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.q11"> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.INTERNET" /> <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>
让我们尝试运行您的应用程序。我假设您已将您的实际 Android 移动设备连接到您的计算机。要从 Android Studio 运行应用程序，请打开您的项目活动文件之一，然后单击工具栏中的运行图标 
。选择您的移动设备作为选项，然后检查您的移动设备，它将显示您的默认屏幕。
点击 这里 下载项目代码。
更新于: 2020-11-28
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