Java quickstart

Quickstarts explain how to set up and run an app that calls a Google Workspace API.

Google Workspace quickstarts use the API client libraries to handle some details of the authentication and authorization flow. We recommend that you use the client libraries for your own apps. This quickstart uses a simplified authentication approach that is appropriate for a testing environment. For a production environment, we recommend learning about authentication and authorization before choosing the access credentials that are appropriate for your app.

Create a Java command-line application that makes requests to the Google Meet API.

Objectives

  • Set up your environment.
  • Set up the sample.
  • Run the sample.

Prerequisites

  • A Google Workspace account with Google Meet enabled.

Set up your environment

To complete this quickstart, set up your environment.

Enable the API

Before using Google APIs, you need to turn them on in a Google Cloud project. You can turn on one or more APIs in a single Google Cloud project.

  • In the Google Cloud console, enable the Google Meet API.

    Enable the API

If you're using a new Google Cloud project to complete this quickstart, configure the OAuth consent screen and add yourself as a test user. If you've already completed this step for your Cloud project, skip to the next section.

  1. In the Google Cloud console, go to Menu > APIs & Services > OAuth consent screen.

    Go to OAuth consent screen

  2. For User type select Internal, then click Create.
  3. Complete the app registration form, then click Save and Continue.

  4. For now, you can skip adding scopes and click Save and Continue. In the future, when you create an app for use outside of your Google Workspace organization, you must change the User type to External, and then, add the authorization scopes that your app requires.

  5. Review your app registration summary. To make changes, click Edit. If the app registration looks OK, click Back to Dashboard.

Authorize credentials for a desktop application

To authenticate end users and access user data in your app, you need to create one or more OAuth 2.0 Client IDs. A client ID is used to identify a single app to Google's OAuth servers. If your app runs on multiple platforms, you must create a separate client ID for each platform.
  1. In the Google Cloud console, go to Menu > APIs & Services > Credentials.

    Go to Credentials

  2. Click Create Credentials > OAuth client ID.
  3. Click Application type > Desktop app.
  4. In the Name field, type a name for the credential. This name is only shown in the Google Cloud console.
  5. Click Create. The OAuth client created screen appears, showing your new Client ID and Client secret.
  6. Click OK. The newly created credential appears under OAuth 2.0 Client IDs.
  7. Save the downloaded JSON file as credentials.json, and move the file to your working directory.

Prepare the workspace

  1. In your working directory, create a new project structure:

    gradle init --type basic
mkdir -p src/main/java src/main/resources

  2. In the src/main/resources/ directory, copy the credentials.json file that you previously downloaded.

  3. Open the default build.gradle file and replace its contents with the following code:

    meet/quickstart/build.gradle
    apply plugin: 'java'
apply plugin: 'application'

mainClassName = 'MeetQuickstart'
sourceCompatibility = 11
targetCompatibility = 11
version = '1.0'

repositories {
    mavenCentral()
}

dependencies {
    implementation 'com.google.cloud:google-cloud-meet:0.3.0'
    implementation 'com.google.auth:google-auth-library-oauth2-http:1.19.0'
    implementation 'com.google.oauth-client:google-oauth-client-jetty:1.34.1'
}

Set up the sample

  1. In the src/main/java/ directory, create a new Java file with a name that matches the mainClassName value in your build.gradle file.

  2. Include the following code in your new Java file:

    meet/quickstart/src/main/java/MeetQuickstart.java
    import java.awt.Desktop;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Collections;
import java.util.List;

import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.google.api.gax.core.FixedCredentialsProvider;
import com.google.apps.meet.v2.CreateSpaceRequest;
import com.google.apps.meet.v2.Space;
import com.google.apps.meet.v2.SpacesServiceClient;
import com.google.apps.meet.v2.SpacesServiceSettings;
import com.google.auth.Credentials;
import com.google.auth.oauth2.ClientId;
import com.google.auth.oauth2.DefaultPKCEProvider;
import com.google.auth.oauth2.TokenStore;
import com.google.auth.oauth2.UserAuthorizer;

/* class to demonstrate use of Drive files list API */
public class MeetQuickstart {
  /**
   * Directory to store authorization tokens for this application.
   */
  private static final String TOKENS_DIRECTORY_PATH = "tokens";

  /**
   * Global instance of the scopes required by this quickstart.
   * If modifying these scopes, delete your previously saved tokens/ folder.
   */
  private static final List<String> SCOPES = Collections
      .singletonList("https://www.googleapis.com/auth/meetings.space.created");

  private static final String CREDENTIALS_FILE_PATH = "/credentials.json";

  private static final String USER = "default";

  // Simple file-based token storage for storing oauth tokens
  private static final TokenStore TOKEN_STORE = new TokenStore() {
    private Path pathFor(String id) {
      return Paths.get(".", TOKENS_DIRECTORY_PATH, id + ".json");
    }

    @Override
    public String load(String id) throws IOException {
      if (!Files.exists(pathFor(id))) {
        return null;
      }
      return Files.readString(pathFor(id));
    }

    @Override
    public void store(String id, String token) throws IOException {
      Files.createDirectories(Paths.get(".", TOKENS_DIRECTORY_PATH));
      Files.writeString(pathFor(id), token);
    }

    @Override
    public void delete(String id) throws IOException {
      if (!Files.exists(pathFor(id))) {
        return;
      }
      Files.delete(pathFor(id));
    }
  };

  /**
   * Initialize a UserAuthorizer for local authorization.
   * 
   * @param callbackUri
   * @return
   */
  private static UserAuthorizer getAuthorizer(URI callbackUri) throws IOException {
    // Load client secrets.
    try (InputStream in = MeetQuickstart.class.getResourceAsStream(CREDENTIALS_FILE_PATH)) {
      if (in == null) {
        throw new FileNotFoundException("Resource not found: " + CREDENTIALS_FILE_PATH);
      }

      ClientId clientId = ClientId.fromStream(in);

      UserAuthorizer authorizer = UserAuthorizer.newBuilder()
          .setClientId(clientId)
          .setCallbackUri(callbackUri)
          .setScopes(SCOPES)
          .setPKCEProvider(new DefaultPKCEProvider() {
            // Temporary fix for https://github.com/googleapis/google-auth-library-java/issues/1373
            @Override
            public String getCodeChallenge() {
              return super.getCodeChallenge().split("=")[0];
            }
          })
          .setTokenStore(TOKEN_STORE).build();
      return authorizer;
    }
  }

  /**
   * Run the OAuth2 flow for local/installed app.
   * 
   * @return An authorized Credential object.
   * @throws IOException If the credentials.json file cannot be found.
   */
  private static Credentials getCredentials()
      throws Exception {

    LocalServerReceiver receiver = new LocalServerReceiver.Builder().build();
    try {
      URI callbackUri = URI.create(receiver.getRedirectUri());
      UserAuthorizer authorizer = getAuthorizer(callbackUri);

      Credentials credentials = authorizer.getCredentials(USER);
      if (credentials != null) {
        return credentials;
      }

      URL authorizationUrl = authorizer.getAuthorizationUrl(USER, "", null);
      if (Desktop.isDesktopSupported() && 
          Desktop.getDesktop().isSupported(Desktop.Action.BROWSE)) {
        Desktop.getDesktop().browse(authorizationUrl.toURI());
      } else {
        System.out.printf("Open the following URL to authorize access: %s\n",
            authorizationUrl.toExternalForm());
      }

      String code = receiver.waitForCode();
      credentials = authorizer.getAndStoreCredentialsFromCode(USER, code, callbackUri);
      return credentials;
    } finally {
      receiver.stop();
    }
  }

  public static void main(String... args) throws Exception {
    // Override default service settings to supply user credentials.
    Credentials credentials = getCredentials();
    SpacesServiceSettings settings = SpacesServiceSettings.newBuilder()
        .setCredentialsProvider(FixedCredentialsProvider.create(credentials))
        .build();

    try (SpacesServiceClient spacesServiceClient = SpacesServiceClient.create(settings)) {
      CreateSpaceRequest request = CreateSpaceRequest.newBuilder()
          .setSpace(Space.newBuilder().build())
          .build();
      Space response = spacesServiceClient.createSpace(request);
      System.out.printf("Space created: %s\n", response.getMeetingUri());
    } catch (IOException e) {
      // TODO(developer): Handle errors
      e.printStackTrace();
    }
  }
}

Run the sample

  1. Run the sample:

    gradle run
  1. The first time you run the sample, it prompts you to authorize access:
    1. If you're not already signed in to your Google Account, sign in when prompted. If you're signed in to multiple accounts, select one account to use for authorization.
    2. Click Accept.

    Your Java application runs and calls the Google Meet API.

    Authorization information is stored in the file system, so the next time you run the sample code, you aren't prompted for authorization.

Next steps