Messages and Parts - JavaMail API - page 57

public void attachFile ( File file ) throws IOException , MessagingException
public void attachFile ( String file ) throws IOException , MessagingException
public void attachFile ( File file , String contentType , String encoding )
throws IOException , MessagingException
public void attachFile ( String file , String contentType , String encoding )
throws IOException , MessagingException
Finally, multiple parts can be added to a part by wrapping them in a Multipart object
and passing that to setContent() :
public void setContent ( Multipart mp ) throws MessagingException ,
IllegalWriteException , IllegalStateException
In this case, the entire message typically has a content type such as multipart/mixed ,
multipart/signed , or multipart/alternative . The individual parts of the message
are all enclosed in one envelope but each part of the message has its own content type,
content encoding, and data. The multiple parts may be used to present different forms
of the same document (e.g., HTML and plain-text mail), a document and metainfor‐
mation about the document (e.g., a message and the MD5 digest of the message), or
several different documents (e.g., a message and several attached files). The next section
expands on this process.
Multipart Messages and File Attachments
The way all the different text and binary file types are encoded into raw text that can be
passed through 7-bit email gateways is fairly ingenious and rather detailed. Fortunately,
the JavaMail API shields you from those details, interesting as they are. To send a mul‐
tipart message using the JavaMail API, all you have to do is add the parts to a
MimeMultipart object, then pass that object to the Message 's setContent() method. To
receive a multipart message, you simply process each of the parts individually.
Most of the methods for building and deconstructing multipart messages are in the
abstract javax.mail.Multipart class:
public abstract class Multipart extends Object
However, since this class is abstract, you'll generally start with a javax.mail.inter‐
net.MimeMultipart object instead:
public class MimeMultipart extends Multipart
Each part you add to a Multipart is an instance of the abstract javax.mail.Body
Part class that implements the Part interface of the last section:
public abstract class BodyPart extends Object implements Part
In Internet email, the concrete subclass of BodyPart you'll use is javax.mail.inter‐
net.MimeBodyPart:
public class MimeBodyPart extends BodyPart implements MimePart