Running on Google App Engine

App Engine-specific helpers make quick work of authenticated calls to APIs, andyou do not need to worry about exchanging code for tokens.

For example:

@OverrideprotectedvoiddoGet(HttpServletRequestreq,HttpServletResponseresp)throwsIOException{AppIdentityCredentialcredential=newAppIdentityCredential(Arrays.asList(UrlshortenerScopes.URLSHORTENER));Urlshortenershortener=newUrlshortener.Builder(newUrlFetchTransport(),newJacksonFactory(),credential).build();UrlHistoryhistory=shortener.URL().list().execute();...}

Auth helpers

If you are building a web app that interacts with a user’s data via an OAuth 2.0-enabled API, we’ve created some helpers to assist you with the process. Thehelpers aim to:

• Simplify the process of obtaining access tokens(AuthorizationCodeFlow).
• Manage tokens, after they are obtained, by marking them asPersistenceCapable.
• Simplify the process of making authenticated calls using the access token’scredential.
• Insulate you from the details of authentication when writing servlets.

Getting started

1. Install the Google API Client Library for Java:
   • Follow thedownload instructions and put the library jar filesinto your war/WEB-INF/lib directory.
   • Alternatively, you can useMaven.
2. Learn about usingOAuth 2.0 with the authorization code flow for Google App Engine applications.
3. Learn about usingOAuth 2.0 with the Google App Engine Identity API.
4. Take a look at theCalendar App Engine sample. This samplecombines our Java library and auth helpers to show you how to access end-userdata from within a Google App Engine web app. The sample also usesGWTfor the user interface.