Step 1: Acquire a SHA1 fingerprint
Step 2: Turn on the Google Calendar API
Step 3: Create a new Android project
Step 4: Prepare the project
Open the app build.gradle file and add dependencies content with the following:
compile('com.google.api-client:google-api-client-android:1.23.0') { exclude group: 'org.apache.httpcomponents' } compile('com.google.apis:google-api-services-calendar:v3-rev273-1.23.0') { exclude group: 'org.apache.httpcomponents' } Create a new Java class called "MainActivity" and replace the contents of the new file with the following code.
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.calendar.CalendarScopes; import com.google.api.client.util.DateTime; import com.google.api.services.calendar.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 Google Calendar API"; private static final String PREF_ACCOUNT_NAME = "accountName"; private static final String[] SCOPES = { CalendarScopes.CALENDAR_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 Google Calendar 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 Google Calendar 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.calendar.Calendar mService = null; private Exception mLastError = null; MakeRequestTask(GoogleAccountCredential credential) { HttpTransport transport = AndroidHttp.newCompatibleTransport(); JsonFactory jsonFactory = JacksonFactory.getDefaultInstance(); mService = new com.google.api.services.calendar.Calendar.Builder( transport, jsonFactory, credential) .setApplicationName("Google Calendar API Android Quickstart") .build(); } /** * Background task to call Google Calendar 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 a list of the next 10 events from the primary calendar. * @return List of Strings describing returned events. * @throws IOException */ private List<String> getDataFromApi() throws IOException { // List the next 10 events from the primary calendar. DateTime now = new DateTime(System.currentTimeMillis()); List<String> eventStrings = new ArrayList<String>(); Events events = mService.events().list("primary") .setMaxResults(10) .setTimeMin(now) .setOrderBy("startTime") .setSingleEvents(true) .execute(); List<Event> items = events.getItems(); for (Event event : items) { DateTime start = event.getStart().getDateTime(); if (start == null) { // All-day events don't have start times, so just use // the start date. start = event.getStart().getDate(); } eventStrings.add( String.format("%s (%s)", event.getSummary(), start)); } return eventStrings; } @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 Google Calendar 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."); } } } }
Step 5: Run the app
