本指南說明如何設定簡單的 Android 應用程式，以便向 YouTube Data API 提出要求。
必要條件
如要執行這個快速入門導覽課程，您需要：
- Android Studio SDK 1.2 以上版本。
- API 23 以上的 Android SDK 套件，包括最新版 Google 存放區、Android 支援資料庫和 Google Play 服務。
- 可在測試裝置上存取網際網路。
- Google 帳戶。
本快速入門導覽課程假設您使用的是 Android Studio IDE (而非獨立的 SDK 工具)，且能輕鬆在 Studio 專案中尋找、建立及編輯檔案。
步驟 1：取得 SHA1 指紋
在終端機中，執行下方的 Keytool 公用程式指令，取得您將用來啟用 API 的 SHA1 指紋。
keytool -exportcert -alias androiddebugkey -keystore ~/.android/debug.keystore -list -v
系統要求您提供 KeyStore 密碼時，請輸入「android」。
Keytool 會將指紋列印至殼層。例如：
$ keytool -exportcert -alias androiddebugkey -keystore ~/.android/debug.keystore -list -v Enter keystore password: Type "android" if using debug.keystore Alias name: androiddebugkey Creation date: Dec 4, 2014 Entry type: PrivateKeyEntry Certificate chain length: 1 Certificate[1]: Owner: CN=Android Debug, O=Android, C=US Issuer: CN=Android Debug, O=Android, C=US Serial number: 503bd581 Valid from: Mon Aug 27 13:16:01 PDT 2012 until: Wed Aug 20 13:16:01 PDT 2042 Certificate fingerprints: MD5: 1B:2B:2D:37:E1:CE:06:8B:A0:F0:73:05:3C:A3:63:DD SHA1: D8:AA:43:97:59:EE:C5:95:26:6A:07:EE:1C:37:8E:F4:F0:C8:05:C8 SHA256: F3:6F:98:51:9A:DF:C3:15:4E:48:4B:0F:91:E3:3C:6A:A0:97:DC:0A:3F:B2:D2:E1:FE:23:57:F5:EB:AC:13:30 Signature algorithm name: SHA1withRSA Version: 3
複製在上述範例中醒目顯示的 SHA1 指紋。
步驟 2：啟用 YouTube Data API
-
使用這個精靈在 Google Developers Console 中建立或選取專案，並自動啟用這個 API。依序點選「繼續」和「前往憑證」。
-
在「建立憑證」頁面上，按一下「取消」按鈕。
-
選取頁面頂端的「OAuth 同意畫面」分頁標籤。選取「Email address」(電子郵件地址)，輸入「Product name」(產品名稱) (如果尚未設定)，然後按一下「Save」(儲存) 按鈕。
-
選取「憑證」分頁標籤，按一下「建立憑證」按鈕，然後選取「OAuth 用戶端 ID」。
- 選取「Android」應用程式類型。
- 將步驟 1 中的 SHA1 指紋複製到「簽署憑證指紋」欄位。
- 在「Package name」(套件名稱) 欄位中輸入
com.example.quickstart。 - 按一下「Create」(建立) 按鈕。
步驟 3：建立新的 Android 專案
- 開啟 Android Studio，然後開啟新的 Android Studio 專案。
- 在「New Project」畫面中，將應用程式命名為「quickstart」。
- 將「Company Domain」設為「example.com」，並確認自動產生的套件名稱與您在步驟 2 中在開發人員控制台輸入的名稱相符。按一下「Next」。
- 在「Target Android Devices」畫面中，勾選「Phone and Tablet」核取方塊，然後選擇「API 14: Android 4.0 (IceCreamSandwich)」的「Minimum SDK」。而不勾選其他核取方塊。按一下「Next」。
- 在「Add an activity to Mobile」畫面中，按一下「Add No Activity」。
- 按一下「Finish」。
此時，Android Studio 會建立並開啟專案。
步驟 4：準備專案
「專案」側欄會顯示 Android Studio 建立的預設專案檔案的可展開清單。在清單中展開 Gradle 指令碼清單，並開啟與「應用程式」模組 (而非專案) 相關聯的 build.gradle 檔案。
- 開啟應用程式
build.gradle檔案，並將內容替換為以下內容： - 在工具列中，依序選取「Tools」>「Android」>「Sync Project with Gradle Files」。藉此取得並提供專案所需的程式庫。
- 找出並開啟預設的
src/main/AndroidManifest.xml檔案。在「Project」側欄中，這個檔案以巢狀結構列於app下方，然後在manifests下方。將檔案內容替換成下列程式碼：<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.quickstart"> <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <uses-permission android:name="android.permission.GET_ACCOUNTS" /> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="YouTube Data API Android Quickstart" android:theme="@style/AppTheme" > <activity android:name=".MainActivity" android:label="YouTube Data API Android Quickstart" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
步驟 5：設定範例
建立新的 Java 類別。方法是先在「Project」側欄中選取 java 資料夾。這個資料夾會顯示在 app 個檔案群組中。按一下資料夾後，可以從選單列中依序選取.../app/src/main/java。
將類別命名為「MainActivity」，然後按一下「OK」。使用下列程式碼取代新檔案的內容。
package com.example.quickstart;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GoogleApiAvailability;
import com.google.api.client.extensions.android.http.AndroidHttp;
import com.google.api.client.googleapis.extensions.android.gms.auth.GoogleAccountCredential;
import com.google.api.client.googleapis.extensions.android.gms.auth.GooglePlayServicesAvailabilityIOException;
import com.google.api.client.googleapis.extensions.android.gms.auth.UserRecoverableAuthIOException;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.util.ExponentialBackOff;
import com.google.api.services.youtube.YouTubeScopes;
import com.google.api.services.youtube.model.*;
import android.Manifest;
import android.accounts.AccountManager;
import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.text.TextUtils;
import android.text.method.ScrollingMovementMethod;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import pub.devrel.easypermissions.AfterPermissionGranted;
import pub.devrel.easypermissions.EasyPermissions;
public class MainActivity extends Activity
implements EasyPermissions.PermissionCallbacks {
GoogleAccountCredential mCredential;
private TextView mOutputText;
private Button mCallApiButton;
ProgressDialog mProgress;
static final int REQUEST_ACCOUNT_PICKER = 1000;
static final int REQUEST_AUTHORIZATION = 1001;
static final int REQUEST_GOOGLE_PLAY_SERVICES = 1002;
static final int REQUEST_PERMISSION_GET_ACCOUNTS = 1003;
private static final String BUTTON_TEXT = "Call YouTube Data API";
private static final String PREF_ACCOUNT_NAME = "accountName";
private static final String[] SCOPES = { YouTubeScopes.YOUTUBE_READONLY };
/**
* Create the main activity.
* @param savedInstanceState previously saved instance data.
*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LinearLayout activityLayout = new LinearLayout(this);
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.MATCH_PARENT);
activityLayout.setLayoutParams(lp);
activityLayout.setOrientation(LinearLayout.VERTICAL);
activityLayout.setPadding(16, 16, 16, 16);
ViewGroup.LayoutParams tlp = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
mCallApiButton = new Button(this);
mCallApiButton.setText(BUTTON_TEXT);
mCallApiButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mCallApiButton.setEnabled(false);
mOutputText.setText("");
getResultsFromApi();
mCallApiButton.setEnabled(true);
}
});
activityLayout.addView(mCallApiButton);
mOutputText = new TextView(this);
mOutputText.setLayoutParams(tlp);
mOutputText.setPadding(16, 16, 16, 16);
mOutputText.setVerticalScrollBarEnabled(true);
mOutputText.setMovementMethod(new ScrollingMovementMethod());
mOutputText.setText(
"Click the \'" + BUTTON_TEXT +"\' button to test the API.");
activityLayout.addView(mOutputText);
mProgress = new ProgressDialog(this);
mProgress.setMessage("Calling YouTube Data API ...");
setContentView(activityLayout);
// Initialize credentials and service object.
mCredential = GoogleAccountCredential.usingOAuth2(
getApplicationContext(), Arrays.asList(SCOPES))
.setBackOff(new ExponentialBackOff());
}
/**
* Attempt to call the API, after verifying that all the preconditions are
* satisfied. The preconditions are: Google Play Services installed, an
* account was selected and the device currently has online access. If any
* of the preconditions are not satisfied, the app will prompt the user as
* appropriate.
*/
private void getResultsFromApi() {
if (! isGooglePlayServicesAvailable()) {
acquireGooglePlayServices();
} else if (mCredential.getSelectedAccountName() == null) {
chooseAccount();
} else if (! isDeviceOnline()) {
mOutputText.setText("No network connection available.");
} else {
new MakeRequestTask(mCredential).execute();
}
}
/**
* Attempts to set the account used with the API credentials. If an account
* name was previously saved it will use that one; otherwise an account
* picker dialog will be shown to the user. Note that the setting the
* account to use with the credentials object requires the app to have the
* GET_ACCOUNTS permission, which is requested here if it is not already
* present. The AfterPermissionGranted annotation indicates that this
* function will be rerun automatically whenever the GET_ACCOUNTS permission
* is granted.
*/
@AfterPermissionGranted(REQUEST_PERMISSION_GET_ACCOUNTS)
private void chooseAccount() {
if (EasyPermissions.hasPermissions(
this, Manifest.permission.GET_ACCOUNTS)) {
String accountName = getPreferences(Context.MODE_PRIVATE)
.getString(PREF_ACCOUNT_NAME, null);
if (accountName != null) {
mCredential.setSelectedAccountName(accountName);
getResultsFromApi();
} else {
// Start a dialog from which the user can choose an account
startActivityForResult(
mCredential.newChooseAccountIntent(),
REQUEST_ACCOUNT_PICKER);
}
} else {
// Request the GET_ACCOUNTS permission via a user dialog
EasyPermissions.requestPermissions(
this,
"This app needs to access your Google account (via Contacts).",
REQUEST_PERMISSION_GET_ACCOUNTS,
Manifest.permission.GET_ACCOUNTS);
}
}
/**
* Called when an activity launched here (specifically, AccountPicker
* and authorization) exits, giving you the requestCode you started it with,
* the resultCode it returned, and any additional data from it.
* @param requestCode code indicating which activity result is incoming.
* @param resultCode code indicating the result of the incoming
* activity result.
* @param data Intent (containing result data) returned by incoming
* activity result.
*/
@Override
protected void onActivityResult(
int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch(requestCode) {
case REQUEST_GOOGLE_PLAY_SERVICES:
if (resultCode != RESULT_OK) {
mOutputText.setText(
"This app requires Google Play Services. Please install " +
"Google Play Services on your device and relaunch this app.");
} else {
getResultsFromApi();
}
break;
case REQUEST_ACCOUNT_PICKER:
if (resultCode == RESULT_OK && data != null &&
data.getExtras() != null) {
String accountName =
data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
if (accountName != null) {
SharedPreferences settings =
getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putString(PREF_ACCOUNT_NAME, accountName);
editor.apply();
mCredential.setSelectedAccountName(accountName);
getResultsFromApi();
}
}
break;
case REQUEST_AUTHORIZATION:
if (resultCode == RESULT_OK) {
getResultsFromApi();
}
break;
}
}
/**
* Respond to requests for permissions at runtime for API 23 and above.
* @param requestCode The request code passed in
* requestPermissions(android.app.Activity, String, int, String[])
* @param permissions The requested permissions. Never null.
* @param grantResults The grant results for the corresponding permissions
* which is either PERMISSION_GRANTED or PERMISSION_DENIED. Never null.
*/
@Override
public void onRequestPermissionsResult(int requestCode,
@NonNull String[] permissions,
@NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
EasyPermissions.onRequestPermissionsResult(
requestCode, permissions, grantResults, this);
}
/**
* Callback for when a permission is granted using the EasyPermissions
* library.
* @param requestCode The request code associated with the requested
* permission
* @param list The requested permission list. Never null.
*/
@Override
public void onPermissionsGranted(int requestCode, List<String> list) {
// Do nothing.
}
/**
* Callback for when a permission is denied using the EasyPermissions
* library.
* @param requestCode The request code associated with the requested
* permission
* @param list The requested permission list. Never null.
*/
@Override
public void onPermissionsDenied(int requestCode, List<String> list) {
// Do nothing.
}
/**
* Checks whether the device currently has a network connection.
* @return true if the device has a network connection, false otherwise.
*/
private boolean isDeviceOnline() {
ConnectivityManager connMgr =
(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
return (networkInfo != null && networkInfo.isConnected());
}
/**
* Check that Google Play services APK is installed and up to date.
* @return true if Google Play Services is available and up to
* date on this device; false otherwise.
*/
private boolean isGooglePlayServicesAvailable() {
GoogleApiAvailability apiAvailability =
GoogleApiAvailability.getInstance();
final int connectionStatusCode =
apiAvailability.isGooglePlayServicesAvailable(this);
return connectionStatusCode == ConnectionResult.SUCCESS;
}
/**
* Attempt to resolve a missing, out-of-date, invalid or disabled Google
* Play Services installation via a user dialog, if possible.
*/
private void acquireGooglePlayServices() {
GoogleApiAvailability apiAvailability =
GoogleApiAvailability.getInstance();
final int connectionStatusCode =
apiAvailability.isGooglePlayServicesAvailable(this);
if (apiAvailability.isUserResolvableError(connectionStatusCode)) {
showGooglePlayServicesAvailabilityErrorDialog(connectionStatusCode);
}
}
/**
* Display an error dialog showing that Google Play Services is missing
* or out of date.
* @param connectionStatusCode code describing the presence (or lack of)
* Google Play Services on this device.
*/
void showGooglePlayServicesAvailabilityErrorDialog(
final int connectionStatusCode) {
GoogleApiAvailability apiAvailability = GoogleApiAvailability.getInstance();
Dialog dialog = apiAvailability.getErrorDialog(
MainActivity.this,
connectionStatusCode,
REQUEST_GOOGLE_PLAY_SERVICES);
dialog.show();
}
/**
* An asynchronous task that handles the YouTube Data API call.
* Placing the API calls in their own task ensures the UI stays responsive.
*/
private class MakeRequestTask extends AsyncTask<Void, Void, List<String>> {
private com.google.api.services.youtube.YouTube mService = null;
private Exception mLastError = null;
MakeRequestTask(GoogleAccountCredential credential) {
HttpTransport transport = AndroidHttp.newCompatibleTransport();
JsonFactory jsonFactory = JacksonFactory.getDefaultInstance();
mService = new com.google.api.services.youtube.YouTube.Builder(
transport, jsonFactory, credential)
.setApplicationName("YouTube Data API Android Quickstart")
.build();
}
/**
* Background task to call YouTube Data API.
* @param params no parameters needed for this task.
*/
@Override
protected List<String> doInBackground(Void... params) {
try {
return getDataFromApi();
} catch (Exception e) {
mLastError = e;
cancel(true);
return null;
}
}
/**
* Fetch information about the "GoogleDevelopers" YouTube channel.
* @return List of Strings containing information about the channel.
* @throws IOException
*/
private List<String> getDataFromApi() throws IOException {
// Get a list of up to 10 files.
List<String> channelInfo = new ArrayList<String>();
ChannelListResponse result = mService.channels().list("snippet,contentDetails,statistics")
.setForUsername("GoogleDevelopers")
.execute();
List<Channel> channels = result.getItems();
if (channels != null) {
Channel channel = channels.get(0);
channelInfo.add("This channel's ID is " + channel.getId() + ". " +
"Its title is '" + channel.getSnippet().getTitle() + ", " +
"and it has " + channel.getStatistics().getViewCount() + " views.");
}
return channelInfo;
}
@Override
protected void onPreExecute() {
mOutputText.setText("");
mProgress.show();
}
@Override
protected void onPostExecute(List<String> output) {
mProgress.hide();
if (output == null || output.size() == 0) {
mOutputText.setText("No results returned.");
} else {
output.add(0, "Data retrieved using the YouTube Data API:");
mOutputText.setText(TextUtils.join("\n", output));
}
}
@Override
protected void onCancelled() {
mProgress.hide();
if (mLastError != null) {
if (mLastError instanceof GooglePlayServicesAvailabilityIOException) {
showGooglePlayServicesAvailabilityErrorDialog(
((GooglePlayServicesAvailabilityIOException) mLastError)
.getConnectionStatusCode());
} else if (mLastError instanceof UserRecoverableAuthIOException) {
startActivityForResult(
((UserRecoverableAuthIOException) mLastError).getIntent(),
MainActivity.REQUEST_AUTHORIZATION);
} else {
mOutputText.setText("The following error occurred:\n"
+ mLastError.getMessage());
}
} else {
mOutputText.setText("Request cancelled.");
}
}
}
}
步驟 6：執行應用程式
- 如要測試應用程式，請依序點選「Run」>「Run app」選單項目。
- 系統會提示您選取用來執行應用程式的已連線裝置 (建議) 或模擬。如果您要執行模擬，請確定設定為使用其中一個「使用 Google API 的」系統映像檔。如果您嘗試在尚未安裝 Google Play 服務的裝置上執行快速入門導覽課程，快速入門導覽課程會產生對話方塊讓您安裝。
- 如果是在模擬器上執行，請允許模擬器完全啟動並建立網路連線。
- 如果是首次啟動模擬器，您可能需要解鎖螢幕。無論如何，快速入門導覽課程應用程式應會自動啟動。
- 首次執行應用程式時，系統會提示您指定帳戶。完成登入流程，選擇要連結的帳戶。
- 選取帳戶後，應用程式會提示您授予存取權。按一下「OK」進行授權。
附註
- 授權資訊會儲存在應用程式，因此後續的執行作業不會提示使用者進行授權。
延伸閱讀
- Google Developers Console 說明文件
- 適用於 Java 的 Google API 用戶端說明文件
- Android API 指南
- Google Play 服務
- YouTube Data API 參考說明文件
疑難排解
未註冊的 Android 應用程式
如果 OAuth 對話方塊中包含「未註冊的 Android 應用程式」項目，表示找不到您在步驟 2 建立的 OAuth2 用戶端 ID，而 Android 將改回預設用戶端。預設用戶端不會設為使用此 API，因此如 accessNotConfigured. 等錯誤導致要求失敗，這些錯誤也可能提及預設專案編號 608941808256。
如要修正這個問題，請確認您在步驟 1 中擷取的 SHA1 指紋與 build.gradle 檔案中列出的 applicationId，與您在 Google Developers Console 中設定的值完全一致。