Java Reference
In-Depth Information
Next, you'll want to create an instance of the
javax.mail.Authenticator
class (more
properly, an instance of a concrete subclass of the abstract
Authenticator
class) that
can ask the user for a password. For now, we'll simply hardcode those values and pass
null
instead of an actual
Authenticator
:
Authenticator
a
=
null
;
We'll fill this piece in later when we discuss authentication.
Next, use these
Properties
and
Authenticator
objects to get a
Session
instance, like
this:
Session
session
=
Session
.
getInstance
(
props
,
a
);
Ask the session for a store for the provider. Here, we want a provider for POP3:
Store
store
=
session
.
getStore
(
"pop3"
);
Finally, you're ready to connect to the store using the
connect()
method. You'll need
to provide the host to connect to and the username and password to use:
store
.
connect
(
"mail.cloud9.net"
,
"elharo"
,
"my_password"
);
You can pass
null
for the password to indicate that the previously specified
Authenti
cator
should be queried for the password.
Now that the store is connected, you're ready to open a folder in the store. This step is
really more oriented to IMAP than POP, since POP servers don't keep track of different
folders. They simply provide all of a user's incoming mail as one undifferentiated amal‐
gam. For purposes of the JavaMail API, POP3 providers use the folder name INBOX:
Folder
inbox
=
store
.
getFolder
(
"INBOX"
);
The folder is closed when you get it. You can perform some operations on a closed folder
including deleting or renaming it, but you can't get the messages out of a closed folder.
First you have to open it. You can open a folder for read access by passing the mnemonic
constant
Folder.READ_WRITE
to the
open()
method for read access, or
Folder.READ_ONLY
for read/write access:
inbox
.
open
(
Folder
.
READ_ONLY
);
Now you're ready to retrieve the messages with the
getMessages()
method, which
returns an array containing pointers to all the messages in the folder:
Message
[]
messages
=
inbox
.
getMessages
();
This call is lazy. That is, it does not actually download the message headers and content.
That will be retrieved later when you ask each message for its data.
The
Message
class provides many methods for working with individual messages. It has
methods to get the various header fields of the message, get the content of the message,
reply to the message, and more. We'll discuss these soon, when we talk about the
Message
