Editor

IdTokenActivity.java

package com.google.samples.quickstart.signin;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
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.auth.api.signin.GoogleSignIn;
import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
import com.google.android.gms.auth.api.signin.GoogleSignInClient;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
import com.google.android.gms.common.api.ApiException;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;

/**
 * Demonstrates retrieving an ID token for the current Google user.
 */
public class IdTokenActivity extends AppCompatActivity implements
        View.OnClickListener {

private static final String TAG = "IdTokenActivity";
    private static final int RC_GET_TOKEN = 9002;

private GoogleSignInClient mGoogleSignInClient;
    private TextView mIdTokenTextView;
    private Button mRefreshButton;

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

// Views
        mIdTokenTextView = findViewById(R.id.detail);
        mRefreshButton = findViewById(R.id.button_optional_action);
        mRefreshButton.setText(R.string.refresh_token);

// Button click listeners
        findViewById(R.id.sign_in_button).setOnClickListener(this);
        findViewById(R.id.sign_out_button).setOnClickListener(this);
        findViewById(R.id.disconnect_button).setOnClickListener(this);
        mRefreshButton.setOnClickListener(this);

// For sample only: make sure there is a valid server client ID.
        validateServerClientID();

// [START configure_signin]
        // Request only the user's ID token, which can be used to identify the
        // user securely to your backend. This will contain the user's basic
        // profile (name, profile picture URL, etc) so you should not need to
        // make an additional call to personalize your application.
        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.server_client_id))
                .requestEmail()
                .build();
        // [END configure_signin]

// Build GoogleAPIClient with the Google Sign-In API and the above options.
        mGoogleSignInClient = GoogleSignIn.getClient(this, gso);
    }

private void getIdToken() {
        // Show an account picker to let the user choose a Google account from the device.
        // If the GoogleSignInOptions only asks for IDToken and/or profile and/or email then no
        // consent screen will be shown here.
        Intent signInIntent = mGoogleSignInClient.getSignInIntent();
        startActivityForResult(signInIntent, RC_GET_TOKEN);
    }

private void refreshIdToken() {
        // Attempt to silently refresh the GoogleSignInAccount. If the GoogleSignInAccount
        // already has a valid token this method may complete immediately.
        //
        // If the user has not previously signed in on this device or the sign-in has expired,
        // this asynchronous branch will attempt to sign in the user silently and get a valid
        // ID token. Cross-device single sign on will occur in this branch.
        mGoogleSignInClient.silentSignIn()
                .addOnCompleteListener(this, new OnCompleteListener<GoogleSignInAccount>() {
                    @Override
                    public void onComplete(@NonNull Task<GoogleSignInAccount> task) {
                        handleSignInResult(task);
                    }
                });
    }

// [START handle_sign_in_result]
    private void handleSignInResult(@NonNull Task<GoogleSignInAccount> completedTask) {
        try {
            GoogleSignInAccount account = completedTask.getResult(ApiException.class);
            String idToken = account.getIdToken();

// TODO(developer): send ID Token to server and validate

updateUI(account);
        } catch (ApiException e) {
            Log.w(TAG, "handleSignInResult:error", e);
            updateUI(null);
        }
    }
    // [END handle_sign_in_result]

private void signOut() {
        mGoogleSignInClient.signOut().addOnCompleteListener(this, new OnCompleteListener<Void>() {
            @Override
            public void onComplete(@NonNull Task<Void> task) {
                updateUI(null);
            }
        });
    }

private void revokeAccess() {
        mGoogleSignInClient.revokeAccess().addOnCompleteListener(this,
                new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task) {
                        updateUI(null);
                    }
                });
    }

@Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

if (requestCode == RC_GET_TOKEN) {
            // [START get_id_token]
            // This task is always completed immediately, there is no need to attach an
            // asynchronous listener.
            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
            handleSignInResult(task);
            // [END get_id_token]
        }
    }

private void updateUI(@Nullable GoogleSignInAccount account) {
        if (account != null) {
            ((TextView) findViewById(R.id.status)).setText(R.string.signed_in);

String idToken = account.getIdToken();
            mIdTokenTextView.setText(getString(R.string.id_token_fmt, idToken));

findViewById(R.id.sign_in_button).setVisibility(View.GONE);
            findViewById(R.id.sign_out_and_disconnect).setVisibility(View.VISIBLE);
            mRefreshButton.setVisibility(View.VISIBLE);
        } else {
            ((TextView) findViewById(R.id.status)).setText(R.string.signed_out);
            mIdTokenTextView.setText(getString(R.string.id_token_fmt, "null"));

findViewById(R.id.sign_in_button).setVisibility(View.VISIBLE);
            findViewById(R.id.sign_out_and_disconnect).setVisibility(View.GONE);
            mRefreshButton.setVisibility(View.GONE);
        }
    }

/**
     * Validates that there is a reasonable server client ID in strings.xml, this is only needed
     * to make sure users of this sample follow the README.
     */
    private void validateServerClientID() {
        String serverClientId = getString(R.string.server_client_id);
        String suffix = ".apps.googleusercontent.com";
        if (!serverClientId.trim().endsWith(suffix)) {
            String message = "Invalid server client ID in strings.xml, must end with " + suffix;

Log.w(TAG, message);
            Toast.makeText(this, message, Toast.LENGTH_LONG).show();
        }
    }

@Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.sign_in_button:
                getIdToken();
                break;
            case R.id.sign_out_button:
                signOut();
                break;
            case R.id.disconnect_button:
                revokeAccess();
                break;
            case R.id.button_optional_action:
                refreshIdToken();
                break;
        }
    }
}