Java第23堂: Read Gmail

package org.hkprog.reademail;

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.gson.GsonFactory;
import com.google.api.client.util.store.FileDataStoreFactory;
import com.google.api.services.gmail.Gmail;
import com.google.api.services.gmail.GmailScopes;
import com.google.api.services.gmail.model.ListMessagesResponse;
import com.google.api.services.gmail.model.Message;
import com.google.api.services.gmail.model.MessagePartHeader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.GeneralSecurityException;
import java.util.ArrayList;
import java.util.List;


/* class to demonstrate use of Gmail list labels API */
public class GmailQuickstart {

	/**
	 * Application name.
	 */
	private static final String APPLICATION_NAME = "Gmail API Java Quickstart";
	/**
	 * Global instance of the JSON factory.
	 */
	private static final JsonFactory JSON_FACTORY = GsonFactory.getDefaultInstance();
	/**
	 * 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(GmailScopes.GMAIL_LABELS);
	private static final List<String> SCOPES = List.of(GmailScopes.MAIL_GOOGLE_COM, GmailScopes.GMAIL_MODIFY, GmailScopes.GMAIL_READONLY);

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

	/**
	 * Creates an authorized Credential object.
	 *
	 * @param HTTP_TRANSPORT The network HTTP Transport.
	 * @return An authorized Credential object.
	 * @throws IOException If the credentials.json file cannot be found.
	 */
	private static Credential getCredentials(final NetHttpTransport HTTP_TRANSPORT)
			throws IOException {
		// Load client secrets.
		InputStream in = GmailQuickstart.class.getResourceAsStream(CREDENTIALS_FILE_PATH);
		if (in == null) {
			throw new FileNotFoundException("Resource not found: " + CREDENTIALS_FILE_PATH);
		}
		GoogleClientSecrets clientSecrets
				= GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));

		// Build flow and trigger user authorization request.
		GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
				HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
				.setDataStoreFactory(new FileDataStoreFactory(new java.io.File(TOKENS_DIRECTORY_PATH)))
				.setAccessType("offline")
				.build();
		LocalServerReceiver receiver = new LocalServerReceiver.Builder().setPort(8888).build();
		Credential credential = new AuthorizationCodeInstalledApp(flow, receiver).authorize("5user");
		//returns an authorized Credential object.
		return credential;
	}

	public static void main(String... args) throws IOException, GeneralSecurityException {
		// Build a new authorized API client service.
		final NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
		Gmail service = new Gmail.Builder(HTTP_TRANSPORT, JSON_FACTORY, getCredentials(HTTP_TRANSPORT))
				.setApplicationName(APPLICATION_NAME)
				.build();

		// Print the labels in the user's account.
		String user = "me";

		ListMessagesResponse response = service.users().messages().list(user).execute();
		for (int x = 0; x < 3; x++) {
			Message message = response.getMessages().get(x);
			Message test = service.users().messages().get("me", message.getId()).execute();
			String subject = null;
			if (test.getPayload() != null) {
				List<MessagePartHeader> headers = test.getPayload().getHeaders();
				for (MessagePartHeader header : headers) {
//					System.out.println("    " + header.getName() + " = " + header.getValue());
					if (header.getName().equals("Subject")) {
						subject = header.getValue();
					}
				}
			}
			System.out.println(subject);
			System.out.println(test.getSnippet());
			System.out.println("---------");
		}
	}
}