This sample shows how to implement an OAuth 2.0 flow using the Google OAuth Client Library for Java to access protected data stored on Google services. OAuth 2.0 is a standard specification for allowing end users to securely authorize a client application to access protected server-side resources.

• Make sure gcloud is installed and initialized:

   gcloud init

• If this is the first time you are creating an App Engine project

   gcloud app create

• Copy the sample apps to your local machine:

  git clone https://github.com/GoogleCloudPlatform/java-docs-samples

• Add the appengine-simple-jetty-main Main class to your classpath:

  cd java-docs-samples/appengine-java11/appengine-simple-jetty-main
  mvn install

• In the Cloud Developers Console > API Manager > Credentials, create a OAuth Client ID for a Web Application. You will need to provide an authorized redirect URI origin: https://<PROJECT_ID>.appspot.com/oauth2callback.

• Replace CLIENT_ID and CLIENT_SECRET with these values in your app.yaml

• Move into the appengine-java11/oauth2 directory and compile the app:

  cd ../oauth2
  mvn package

mvn clean package appengine:deploy

To view your app, use command:

gcloud app browse

Or navigate to https://<your-project-id>.appspot.com.