java - Processing a Raw Email Data using Java

Question

I'm having a DB which stores raw email contents. My requirement is to fetch individual mails from the DB and process that data to fetch the basic details of that particular email (such as FROM, TO, SUBJECT, etc..) and also to get all the attachments saved to the file system using Core Java. Currently I'm able to fetch the raw email data from DB as a String, but not able to process that data.

How to process this raw email data (String data type) using Java?

Edit: In the DB level the data is stored as NCLOB. After fetching the data from the DB, it is then stored as a Java String data type.

A sample email data is:

From: Support-BPM-CholaMS <support.bpm@mydomain>
To: "faxhealthuat@mydomain.com" <faxhealthuat@mydomain.com>
Subject: Test From Mail
Thread-Topic: Test From Mail
Thread-Index: AdFuHx8uv6VR8hDtQvKILSCahVrrMg==
Date: Tue, 23 Feb 2016 09:46:39 +0000
Message-ID: <B8C5C607CDD50E4D84DACA129D4CFD64C7299C49@CHNMURROOTMBX2.murugappa.com>
Accept-Language: en-US
Content-Language: en-US
Content-Type: multipart/alternative;
    boundary="_000_B8C5C607CDD50E4D84DACA129D4CFD64C7299C49CHNMURROOTMBX2m_"
MIME-Version: 1.0

--_000_B8C5C607CDD50E4D84DACA129D4CFD64C7299C49CHNMURROOTMBX2m_
Content-Type: text/plain; charset="us-ascii"
content-transfer-encoding: quoted-printable

Testing for from mail fetch

--_000_B8C5C607CDD50E4D84DACA129D4CFD64C7299C49CHNMURROOTMBX2m_
Content-Type: text/html; charset="us-ascii"
content-transfer-encoding: quoted-printable
--_000_B8C5C607CDD50E4D84DACA129D4CFD64C7299C49CHNMURROOTMBX2m_--

score 0 · Accepted Answer

Assuming the string you are fetching contains the new line delimiter

String rawEmail = "YOUR EMAIL CONTENTS";
String [] lines =  rawEmail.split("\\r?\\n");
Map<String, String> attributes = new HashMap<>();
for(String line : lines)
{
    String [] tokens = line.split(":");
    if(!tokens[0].isEmpty()) 
    {
        attributes.put(tokens[0].trim(), tokens[1].isEmpty()? null : tokens[1].trim());
    }
}

Further processing for nested attributes would be done the same way

score 0 · Accepted Answer

Well if you want to parse an email message, you just need to know the format of an email message. This was once defined in RFC822, obsoleted by RFC2822, obsoleted by RFC5322. You should read those documents first, and choose what part of them you want to be able to process.

At the highest level, a message in composed of lines. Those lines should be terminated with \r\n (CrLf), but you should not rely on that since you a getting your messages from a DB without knowing whether any pre-processing has occured. First comes a header (containing header lines) and optionaly a body separated from the header by an empty line.

Header lines or of the form HEADER_NAME:HEADER_VALUE where the header name must not begin with a space. In the header part, any line beginning with a space is a continuation line and must be concatenated to the value of previous line.

For more details, just refere to RFC 5322.

score 0 · Accepted Answer

Well, after doing some research based on your answers & comments, I got what I needed. Thank you all for your efforts.

Just sharing the same here. The below Java method will fetch the email raw data from the database, find and save all the attachments contained in the email data to the file system, and finally returns either a success or a failure message.

public static String saveAttachments(String EMAIL_ID)
{
    try
    {
        String saveDirectory = "C:\\Email\\Attachements\\";

        //Get email record from DB
        EMAIL newEMAILObj = EMAIL.getEmailDetailsForEmailId(EMAIL_ID);

        //Get email raw data into a String variable
        String emailRawData = newEMAILObj.getCONTENT();

        Session newSession = Session.getDefaultInstance(new Properties());
        InputStream inputStreamObj = new ByteArrayInputStream(emailRawData.getBytes());
        MimeMessage mimeMessageObj = new MimeMessage(newSession, inputStreamObj);
        String contentType = mimeMessageObj.getContentType();

        if (contentType.contains("multipart")) //Content may contain attachments
        {
            Multipart multiPart = (Multipart) mimeMessageObj.getContent();
            int numberOfParts = multiPart.getCount();
            for (int partCount = 0; partCount < numberOfParts; partCount++)
            {
                MimeBodyPart part = (MimeBodyPart) multiPart.getBodyPart(partCount);
                if (Part.ATTACHMENT.equalsIgnoreCase(part.getDisposition())) //This part is an attachment
                {
                    File file = new File(saveDirectory+part.getFileName());
                    part.saveFile(file);
                }
            }
        }
    }
    catch (MessagingException ex) 
    {
        return "FAILED: "+ex.getLocalizedMessage();
    }
    catch (IOException ex)
    {
        return "FAILED: "+ex.getLocalizedMessage();
    } 
    return "SUCCESS";
}

java - Processing a Raw Email Data using Java

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