Messages and Parts - JavaMail API - page 56

public Object getContent () throws IOException , MessagingException
This is reminiscent of the getContent() method of java.net.URL . However, rather
than relying on the poorly designed content handler mechanism, this getContent()
method uses the Java Activation Framework, so the behavior is a little more clearly
specified. Most of the time, if the content type is text/plain , a String will be returned.
If the content type is multipart, then regardless of the subtype, a javax.mail.Multi
part object is returned. If the content type is some other type that is recognized by the
underlying DataHandler , an appropriate Java object is returned. Finally, if the type is
unrecognized, an InputStream is returned.
Another way to read the contents of a part is by writing them onto an OutputStream
using the writeTo() method. If necessary, it will encode the content using Base64,
quoted-printable, or some other format as specified by the DataHandler :
public void writeTo ( OutputStream out )
throws IOException , MessagingException
In fact, this not only writes the content of this Part , it also writes the attributes and
headers of the part. Example 6-1 used this to provide a simple way of getting an entire
email message in one fell swoop. It's most convenient, though, when you want to send
an entire message to an SMTP server in one method call.
If the part is not just a part, but specifically a MimeBodyPart (and most attachments in
regular Internet email will be MimeBodyPart s) then you can also use the saveFile()
method to write the decoded contents of the part into a file:
public void saveFile ( File file ) throws IOException , MessagingException
public void saveFile ( String file ) throws IOException , MessagingException
Writing the contents of the part
When sending a message, you naturally must set the message's contents. Since email
messages are text, the most straightforward way is just to provide the text of the part
with setText() :
public void setText ( String text ) throws MessagingException ,
IllegalWriteException , IllegalStateException
The setText() method sets the MIME type to text/plain . Other objects can be made
into content as well, provided the part has a DataHandler that understands how to
convert them to encoded text. This is done with the setContent() method:
public void setContent ( Object o , String type ) throws
MessagingException , IllegalWriteException , IllegalStateException
Assuming you're sending Internet email, the concrete Part subclass will likely be Mime
BodyPart , and in that case then you can also use the attachFile() method to encode
the contents of a file into the message: