在java中创建一个email object并保存到文件中

Question

i need to backup the emails contained in a PST file (outlook storage). i'm using libpst which is the only free library i found on the web ( http://code.google.com/p/java-libpst/ )

so i can access all the information in each single email (subject, body, sender ecc..), but i need to put them on a file

here someone said you can create an EML file from a "javax.mail.Message" object: Create a.eml (email) file in Java

the problem is: how do i create this Message object? i don't have a server or an email session, just the information contained in the email

ps creating a.msg file would be fine too

Answer 1

Here's the code to create a valid eml file with java mail api. works fine with thunderbird and probably other email clients:

public static void createMessage(String to, String from, String subject, String body, List<File> attachments) {
    try {
        Message message = new MimeMessage(Session.getInstance(System.getProperties()));
        message.setFrom(new InternetAddress(from));
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to));
        message.setSubject(subject);
        // create the message part 
        MimeBodyPart content = new MimeBodyPart();
        // fill message
        content.setText(body);
        Multipart multipart = new MimeMultipart();
        multipart.addBodyPart(content);
        // add attachments
        for(File file : attachments) {
            MimeBodyPart attachment = new MimeBodyPart();
            DataSource source = new FileDataSource(file);
            attachment.setDataHandler(new DataHandler(source));
            attachment.setFileName(file.getName());
            multipart.addBodyPart(attachment);
        }
        // integration
        message.setContent(multipart);
        // store file
        message.writeTo(new FileOutputStream(new File("c:/mail.eml")));
    } catch (MessagingException ex) {
        Logger.getLogger(Mailkit.class.getName()).log(Level.SEVERE, null, ex);
    } catch (IOException ex) {
        Logger.getLogger(Mailkit.class.getName()).log(Level.SEVERE, null, ex);
    }
}

Answer 2

You create a Message object the same way you would create one for sending, but instead of sending it you write it to a file. You don't need an email server. There's lots of examples of creating messages in the demo programs included with the JavaMail download , and in the JavaMail FAQ . See the Message.writeTo method to write the message to a file (Message is a Part, and writeTo is on Part).

Answer 3

You can use mimeMessageHelper to create the message, as given below:

    import org.springframework.mail.javamail.MimeMessageHelper;
    
    public methodTocreateMessageObject(){
    MimeMessage message = mailSender.createMimeMessage();
    
    MimeMessageHelper mh= new MimeMessageHelper(message, true);
    mh.setSubject(subject);
    mh.setTo(toArray(to));
    if (CollectionUtils.isNotEmpty(cc)) {
    mh.setCc(toArray(cc));
    }
    mh.setFrom(from);
    
    mh.setText(body, true);
    
            if (attachmentFilenames != null) {
                for (String filename : attachmentFilenames) {
                    FileSystemResource file = new FileSystemResource(filename);
                    mh.addAttachment(file.getFilename(), file);
                }
            }
    
            if (inlineAttachments != null && contentType!=null) {
                for (Entry<String, byte[]> inlineAttach : inlineAttachments.entrySet()) {
    
                    String cId = inlineAttach.getKey();
                    byte[] attachInByteStream = inlineAttach.getValue();
                    InputStreamSource attachSource = new ByteArrayResource(attachInByteStream);
                    mh.addInline(cId, attachSource, contentType);
    
                }
            }
ByteArrayOutputStream output = new ByteArrayOutputStream();
        message.writeTo(output);

        Date lastUpdatetime = new Date();

        try(OutputStream outputStream = new FileOutputStream("D:/mail2.eml")) {
            output.writeTo(outputStream);
        }
    }