GoogleGmailProvider.java

package orchi.HHCloud.mail;


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.repackaged.org.apache.commons.codec.binary.Base64;
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.Message;
import orchi.HHCloud.Start;
import orchi.HHCloud.mail.Exceptions.SendEmailException;

import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.SocketTimeoutException;
import java.security.GeneralSecurityException;
import java.util.Arrays;
import java.util.List;
import java.util.Properties;

public class GoogleGmailProvider implements MailProvider {
    private static final String APPLICATION_NAME = Start.conf.getString("app.name");
    private static final String APPLICATION_ADMIN = Start.conf.getString("mail.mailmanager.mail.admin");
    private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    private static final String TOKENS_DIRECTORY_PATH = "tokens";

    private static final List<String> SCOPES = Arrays.asList(GmailScopes.GMAIL_SEND, GmailScopes.GMAIL_LABELS);
    private static final String CREDENTIALS_FILE_PATH = "/credentials.json";
    private static Gmail service;

    private static Credential getCredentials(final NetHttpTransport HTTP_TRANSPORT) throws IOException {
        // Load client secrets.
        InputStream in = GoogleGmailProvider.class.getResourceAsStream(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();
        return new AuthorizationCodeInstalledApp(flow, new LocalServerReceiver()).authorize("user");
    }

    private static MimeMessage createEmail(String from, String to, String subject, String bodyText)
            throws MessagingException {
        Properties props = new Properties();
        Session session = Session.getDefaultInstance(props, null);

        MimeMessage email = new MimeMessage(session);

        email.setFrom(new InternetAddress(from));
        email.addRecipient(javax.mail.Message.RecipientType.TO, new InternetAddress(to));
        email.setSubject(subject);
        email.setContent(bodyText, "text/html; charset=\"UTF-8\"");
        return email;
    }

    private static Message createMessageWithEmail(MimeMessage emailContent) throws MessagingException, IOException {
        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
        emailContent.writeTo(buffer);
        byte[] bytes = buffer.toByteArray();
        String encodedEmail = Base64.encodeBase64URLSafeString(bytes);
        Message message = new Message();
        message.setRaw(encodedEmail);
        return message;
    }

    private static Message sendMessage(Gmail service, String userId, MimeMessage emailContent)
            throws MessagingException, IOException {
        Message message = createMessageWithEmail(emailContent);
        message = service.users().messages().send(userId, message).execute();

        System.out.println("Message id: " + message.getId());
        System.out.println(message.toPrettyString());
        return message;
    }

    public void init() {

        try {
            final NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
            service = new Gmail.Builder(HTTP_TRANSPORT, JSON_FACTORY, getCredentials(HTTP_TRANSPORT))
                    .setApplicationName(APPLICATION_NAME)
                    .build();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (GeneralSecurityException e) {
            e.printStackTrace();
        }

    }

    @Override
    public void sendEmail(String from, String to, String subject, String body) throws SendEmailException {
        try {
            sendMessage(service, APPLICATION_ADMIN, createEmail(from, to, subject, body));
        } catch (SocketTimeoutException e) {
            e.printStackTrace();
            throw new SendEmailException(e);
        } catch (MessagingException e) {
            e.printStackTrace();
            throw new SendEmailException(e);
        } catch (IOException e) {
            e.printStackTrace();
            throw new SendEmailException(e);
        }

    }
}