gistfile1.java

import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.drive.DriveScopes;
import com.google.code.samples.oauth2.OAuth2Authenticator;
import com.sun.mail.imap.IMAPStore;
import java.io.File;
import java.io.IOException;
import java.security.GeneralSecurityException;

/**
 *
 * Usage explanied here:
 * http://code.google.com/p/java-gmail-imap/wiki/GmailAndXOAUTH2
 *
 */
public class GMailExample {
    
     
    private static final HttpTransport HTTP_TRANSPORT = new NetHttpTransport();
    private static final JsonFactory JSON_FACTORY = new JacksonFactory();
    private static final String GMAIL_SCOPE = "https://mail.google.com/";

    public static void main(String[] args) throws Exception {
        
        String authToken = getAccessToken(SingleUserCredentials.EMAIL);

        OAuth2Authenticator.initialize();

        IMAPStore imapSslStore = OAuth2Authenticator.connectToImap("imap.gmail.com",
                993,
                "[email protected]",
                authToken,
                true);

        System.out.println("Successfully authenticated to IMAP.\n");
    }

    public static String getAccessToken() throws GeneralSecurityException, IOException {
                HttpTransport httpTransport = new NetHttpTransport();
        JacksonFactory jsonFactory = new JacksonFactory();
        
        GoogleCredential credential = new GoogleCredential.Builder()
                .setTransport(httpTransport)
                .setJsonFactory(jsonFactory)
                .setServiceAccountId(SingleUserCredentials.SERVICE_ACCOUNT_EMAIL)
                .setServiceAccountScopes(GMAIL_SCOPE)
                .setServiceAccountPrivateKeyFromP12File(
                new java.io.File(SingleUserCredentials.SERVICE_ACCOUNT_PKCS12_FILE_PATH))
                .build();
        
        credential.refreshToken();
        return credential.getAccessToken();
    }
}