Chapter 19 Using the JavaMail API

This chapter describes how to use the JavaMail^TM API, which provides a set of abstract classes defining objects that comprise a mail system.

This chapter contains the following sections:

• Introducing JavaMail

• Creating a JavaMail Session

• JavaMail Session Properties

• Looking Up a JavaMail Session

• Sending and Reading Messages Using JavaMail

Introducing JavaMail

The JavaMail API defines classes such as Message, Store, and Transport. The API can be extended and can be subclassed to provide new protocols and to add functionality when necessary. In addition, the API provides concrete subclasses of the abstract classes. These subclasses, including MimeMessage and MimeBodyPart, implement widely used Internet mail protocols and conform to the RFC822 and RFC2045 specifications. The JavaMail API includes support for the IMAP4, POP3, and SMTP protocols.

The JavaMail architectural components are as follows:

• The abstract layer declares classes, interfaces, and abstract methods intended to support mail handling functions that all mail systems support.

• The internet implementation layer implements part of the abstract layer using the RFC822 and MIME internet standards.

• JavaMail uses the JavaBeans Activation Framework (JAF) to encapsulate message data and to handle commands intended to interact with that data.

For more information, see Chapter 5, Configuring JavaMail Resources, in Sun Java System Application Server 9.1 Administration Guide and the JavaMail specification at http://java.sun.com/products/javamail/. A useful JavaMail tutorial is located at http://java.sun.com/developer/onlineTraining/JavaMail/.

Creating a JavaMail Session

You can create a JavaMail session in the following ways:

• In the Admin Console, open the Resources component and select JavaMail Sessions. For details, click the Help button in the Admin Console.

• Use the asadmin create-javamail-resource command. For details, see the Sun Java System Application Server 9.1 Reference Manual.

JavaMail Session Properties

You can set properties for a JavaMail Session object. Every property name must start with a mail- prefix. The Application Server changes the dash (-) character to a period (.) in the name of the property and saves the property to the MailConfiguration and JavaMail Session objects. If the name of the property doesn’t start with mail-, the property is ignored.

For example, if you want to define the property mail.from in a JavaMail Session object, first define the property as follows:

• Name – mail-from

• Value – john.doe@sun.com

Looking Up a JavaMail Session

The standard Java Naming and Directory Interface (JNDI) subcontext for JavaMail sessions is java:comp/env/mail.

Registering JavaMail sessions in the mail naming subcontext of a JNDI namespace, or in one of its child subcontexts, is standard. The JNDI namespace is hierarchical, like a file system’s directory structure, so it is easy to find and nest references. A JavaMail session is bound to a logical JNDI name. The name identifies a subcontext, mail, of the root context, and a logical name. To change the JavaMail session, you can change its entry in the JNDI namespace without having to modify the application.

The resource lookup in the application code looks like this:

InitialContext ic = new InitialContext();
String snName = "java:comp/env/mail/MyMailSession";
Session session = (Session)ic.lookup(snName);

For more information about the JNDI API, see Chapter 17, Using the Java Naming and Directory Interface.

Sending and Reading Messages Using JavaMail

The following sections describe how to send and read messages using the JavaMail API:

• To Send a Message Using JavaMail

• To Read a Message Using JavaMail

To Send a Message Using JavaMail

1. Import the packages that you need.

   import java.util.*;
   import javax.activation.*;
   import javax.mail.*;
   import javax.mail.internet.*;
   import javax.naming.*;

2. Look up the JavaMail session.

   InitialContext ic = new InitialContext();
   String snName = "java:comp/env/mail/MyMailSession";
   Session session = (Session)ic.lookup(snName);

   For more information, see Looking Up a JavaMail Session.

3. Override the JavaMail session properties if necessary.

   For example:

   Properties props = session.getProperties();
   props.put("mail.from", "user2@mailserver.com");

4. Create a MimeMessage.

   The msgRecipient, msgSubject, and msgTxt variables in the following example contain input from the user:

   Message msg = new MimeMessage(session);
   msg.setSubject(msgSubject);
   msg.setSentDate(new Date());
   msg.setFrom();
   msg.setRecipients(Message.RecipientType.TO, 
      InternetAddress.parse(msgRecipient, false));
   msg.setText(msgTxt);

5. Send the message.

   Transport.send(msg);

To Read a Message Using JavaMail

1. Import the packages that you need.

   import java.util.*;
   import javax.activation.*;
   import javax.mail.*;
   import javax.mail.internet.*;
   import javax.naming.*;

2. Look up the JavaMail session.

   InitialContext ic = new InitialContext();
   String snName = "java:comp/env/mail/MyMailSession";
   Session session = (javax.mail.Session)ic.lookup(snName);

   For more information, see Looking Up a JavaMail Session.

3. Override the JavaMail session properties if necessary.

   For example:

   Properties props = session.getProperties();
   props.put("mail.from", "user2@mailserver.com");

4. Get a Store object from the Session, then connect to the mail server using the Store object’s connect() method.

   You must supply a mail server name, a mail user name, and a password.

   Store store = session.getStore();
   store.connect("MailServer", "MailUser", "secret");

5. Get the INBOX folder.

   Folder folder = store.getFolder("INBOX");

6. It is efficient to read the Message objects (which represent messages on the server) into an array.

   Message[] messages = folder.getMessages();