在java中获取谷歌的电子邮件/用户名？

import com.google.api.client.auth.oauth2.AuthorizationCodeFlow;
import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp;
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
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.client.util.store.FileDataStoreFactory;
import com.google.api.services.plus.Plus;
import com.google.api.services.plus.model.Person;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.GeneralSecurityException;
import java.util.Collections;

public class GoogleEmailExample {

    private static final String APPLICATION_NAME = "Google Email Example";
    private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    private static final String TOKENS_DIRECTORY_PATH = "tokens";

    private static final List<String> SCOPES = Collections.singletonList("https://www.googleapis.com/auth/plus.me");
    private static final String CREDENTIALS_FILE_PATH = "/path/to/your/credentials.json";

    public static void main(String[] args) throws IOException, GeneralSecurityException {
        // Load client secrets.
        InputStream in = new FileInputStream(CREDENTIALS_FILE_PATH);
        GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));

        // Build flow and trigger user authorization request.
        NetHttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
        FileDataStoreFactory dataStoreFactory = new FileDataStoreFactory(new File(TOKENS_DIRECTORY_PATH));
        AuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(httpTransport, JSON_FACTORY, clientSecrets, SCOPES)
                .setDataStoreFactory(dataStoreFactory)
                .build();
        Credential credential = new AuthorizationCodeInstalledApp(flow, new LocalServerReceiver()).authorize("user");

        // Build Plus service and get user's email.
        Plus plusService = new Plus.Builder(httpTransport, JSON_FACTORY, credential)
                .setApplicationName(APPLICATION_NAME)
                .build();
        Person person = plusService.people().get("me").execute();
        String email = person.getEmails().get(0).getValue();
        System.out.println("User's email: " + email);
    }
}