如要透過 Google Play 服務 (例如 Google 登入或 ML Kit) 支援的 SDK 呼叫其中一個 API，您必須先建立 API 用戶端物件的執行個體。這些物件會自動管理與 Google Play 服務的連線。建立連線時，每個 API 用戶端物件都會依序執行要求。否則，用戶端物件會將要求排入佇列。除非說明文件另有規定，否則用戶端物件的建構成本較低；您可以在每次叫用 API 方法時建立新的 API 用戶端。
本指南說明如何向 Google Play 服務支援的任何 SDK 發出 API 呼叫，包括如何存取不需要授權的服務以及需要授權的服務。
開始使用
首先，請按照設定 Google Play 服務指南中所述，在應用程式專案中新增必要的工具和依附元件。
不需要授權也能存取
如要存取不需要 API 授權的服務，請取得服務的用戶端物件執行個體，並傳送目前的 Context 或目前的 Activity。在執行任何 API 呼叫之前，系統會提示使用者視需要升級 Google Play 服務。
舉例來說，如要透過 Android 的整合式位置預測提供工具取得裝置的最後已知位置，請新增以下程式碼片段所示的邏輯：
Kotlin
// Code required for requesting location permissions omitted for brevity. val client = LocationServices.getFusedLocationProviderClient(this) // Get the last known location. In some rare situations, this can be null. client.lastLocation.addOnSuccessListener { location : Location? -> location?.let { // Logic to handle location object. } }
Java
// Code required for requesting location permissions omitted for brevity. FusedLocationProviderClient client = LocationServices.getFusedLocationProviderClient(this); // Get the last known location. In some rare situations, this can be null. client.getLastLocation() .addOnSuccessListener(this, location -> { if (location != null) { // Logic to handle location object. } });
需要授權時才能存取
如要存取需要使用者授權的服務，請完成下列步驟：
- 登入使用者帳戶。
- 要求權限以存取服務所需的範圍。
- 取得服務用戶端物件的例項，並除了
Context或Activity物件，一併傳送使用者的GoogleSignInAccount物件。
以下範例使用 Google Fit API 讀取使用者的每日步數。如要在完整專案中查看類似的實作，請在 GitHub 上查看 BasicHistoryApiKotlin 應用程式的主活動。
Kotlin
class FitFragment : Fragment() {
private val fitnessOptions: FitnessOptions by lazy {
FitnessOptions.builder()
.addDataType(DataType.TYPE_STEP_COUNT_CUMULATIVE)
.addDataType(DataType.TYPE_STEP_COUNT_DELTA)
.build()
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
fitSignIn()
}
/*
* Checks whether the user is signed in. If so, executes the specified
* function. If the user is not signed in, initiates the sign-in flow,
* specifying the function to execute after the user signs in.
*/
private fun fitSignIn() {
if (oAuthPermissionsApproved()) {
readDailySteps()
} else {
GoogleSignIn.requestPermissions(
this,
SIGN_IN_REQUEST_CODE,
getGoogleAccount(),
fitnessOptions
)
}
}
private fun oAuthPermissionsApproved() =
GoogleSignIn.hasPermissions(getGoogleAccount(), fitnessOptions)
/*
* Gets a Google account for use in creating the fitness client. This is
* achieved by either using the last signed-in account, or if necessary,
* prompting the user to sign in. It's better to use the
* getAccountForExtension() method instead of the getLastSignedInAccount()
* method because the latter can return null if there has been no sign in
* before.
*/
private fun getGoogleAccount(): GoogleSignInAccount =
GoogleSignIn.getAccountForExtension(requireContext(), fitnessOptions)
/*
* Handles the callback from the OAuth sign in flow, executing the function
* after sign-in is complete.
*/
override fun onActivityResult(
requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data)
when (resultCode) {
RESULT_OK -> {
readDailySteps()
}
else -> {
// Handle error.
}
}
}
/*
* Reads the current daily step total.
*/
private fun readDailySteps() {
Fitness.getHistoryClient(requireContext(), getGoogleAccount())
.readDailyTotal(DataType.TYPE_STEP_COUNT_DELTA)
.addOnSuccessListener { dataSet ->
val total = when {
dataSet.isEmpty -> 0
else -> dataSet.dataPoints.first()
.getValue(Field.FIELD_STEPS).asInt()
}
Log.i(TAG, "Total steps: $total")
}
.addOnFailureListener { e ->
Log.w(TAG, "There was a problem getting the step count.", e)
}
}
companion object {
const val SIGN_IN_REQUEST_CODE = 1001
}
}
Java
public class FitFragment extends Fragment {
private final FitnessOptions fitnessOptions = FitnessOptions.builder()
.addDataType(DataType.TYPE_STEP_COUNT_CUMULATIVE)
.addDataType(DataType.TYPE_STEP_COUNT_DELTA)
.build();
@Override
public void onViewCreated(
@NotNull View view, @Nullable Bundle savedInstanceState) {
fitSignIn();
}
/*
* Checks whether the user is signed in. If so, executes the specified
* function. If the user is not signed in, initiates the sign-in flow,
* specifying the function to execute after the user signs in.
*/
private void fitSignIn() {
if (oAuthPermissionsApproved()) {
readDailySteps();
} else {
GoogleSignIn.requestPermissions(this, SIGN_IN_REQUEST_CODE,
getGoogleAccount(), fitnessOptions);
}
}
private boolean oAuthPermissionsApproved() {
return GoogleSignIn.hasPermissions(getGoogleAccount(), fitnessOptions);
}
/*
* Gets a Google account for use in creating the fitness client. This is
* achieved by either using the last signed-in account, or if necessary,
* prompting the user to sign in. It's better to use the
* getAccountForExtension() method instead of the getLastSignedInAccount()
* method because the latter can return null if there has been no sign in
* before.
*/
private GoogleSignInAccount getGoogleAccount() {
return GoogleSignIn.getAccountForExtension(
requireContext(), fitnessOptions);
}
/*
* Handles the callback from the OAuth sign in flow, executing the function
* after sign-in is complete.
*/
@Override
public void onActivityResult(
int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK) {
readDailySteps();
} else {
// Handle error.
}
}
/*
* Reads the current daily step total.
*/
private void readDailySteps() {
AtomicInteger total = new AtomicInteger();
Fitness.getHistoryClient(requireContext(), getGoogleAccount())
.readDailyTotal(DataType.TYPE_STEP_COUNT_DELTA)
.addOnSuccessListener(dataSet -> {
if (!dataSet.isEmpty())
total.set(Integer.parseInt(dataSet.getDataPoints()
.get(0).getValue(FIELD_STEPS).toString()));
Log.i(TAG, "Total steps: $total");
})
.addOnFailureListener(e -> {
Log.w(TAG, "There was a problem getting the step count.", e);
});
}
private static final int SIGN_IN_REQUEST_CODE = 1001;
}
檢查 API 可用性
在應用程式中啟用依附於 Google Play 服務 API 的功能之前，請先檢查裝置上的 API 是否可用。方法是呼叫 checkApiAvailability()。
下列程式碼片段說明如何檢查整合式位置預測提供工具的可用性。
Kotlin
fun getLastLocationIfApiAvailable(context: Context?): Task<Location>? {
val client = getFusedLocationProviderClient(context)
return GoogleApiAvailability.getInstance()
.checkApiAvailability(client)
.onSuccessTask { _ -> client.lastLocation }
.addOnFailureListener { _ -> Log.d(TAG, "Location unavailable.")}
}
Java
public Task<Location> getLastLocationIfApiAvailable(Context context) {
FusedLocationProviderClient client =
getFusedLocationProviderClient(context);
return GoogleApiAvailability.getInstance()
.checkApiAvailability(client)
.onSuccessTask(unused -> client.getLastLocation())
.addOnFailureListener(e -> Log.d(TAG, "Location unavailable."));
}