24.2 Usage

Let's assume there is a business interface called OrderManager:

public interface OrderManager {

    void placeOrder(Order order);
}

Let us also assume that there is a requirement stating that an email message with an order number needs to be generated and sent to a customer placing the relevant order.

24.2.1 Basic MailSender and SimpleMailMessage usage

import org.springframework.mail.MailException;
import org.springframework.mail.MailSender;
import org.springframework.mail.SimpleMailMessage;

public class SimpleOrderManager implements OrderManager {

    private MailSender mailSender;
    private SimpleMailMessage templateMessage;

    public void setMailSender(MailSender mailSender) {
        this.mailSender = mailSender;
    }

    public void setTemplateMessage(SimpleMailMessage templateMessage) {
        this.templateMessage = templateMessage;
    }

    public void placeOrder(Order order) {

        // Do the business calculations...

        // Call the collaborators to persist the order...

        // Create a thread safe "copy" of the template message and customize it
        SimpleMailMessage msg = new SimpleMailMessage(this.templateMessage);
        msg.setTo(order.getCustomer().getEmailAddress());
        msg.setText(
            "Dear " + order.getCustomer().getFirstName()
                + order.getCustomer().getLastName()
                + ", thank you for placing order. Your order number is "
                + order.getOrderNumber());
        try{
            this.mailSender.send(msg);
        }
        catch(MailException ex) {
            // simply log it and go on...
            System.err.println(ex.getMessage());            
        }
    }
}

Find below the bean definitions for the above code:

<bean id="mailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">
  <property name="host" value="mail.mycompany.com"/>
</bean>

<!-- this is a template message that we can pre-load with default state -->
<bean id="templateMessage" class="org.springframework.mail.SimpleMailMessage">
  <property name="from" value="[email protected]"/>
  <property name="subject" value="Your order"/>
</bean>

<bean id="orderManager" class="com.mycompany.businessapp.support.SimpleOrderManager">
  <property name="mailSender" ref="mailSender"/>
  <property name="templateMessage" ref="templateMessage"/>
</bean>

24.2.2 Using the JavaMailSender and the MimeMessagePreparator

Here is another implementation of OrderManager using the MimeMessagePreparator callback interface. Please note in this case that the mailSender property is of type JavaMailSender so that we are able to use the JavaMail MimeMessage class:

import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

import javax.mail.internet.MimeMessage;
import org.springframework.mail.MailException;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessagePreparator;

public class SimpleOrderManager implements OrderManager {

    private JavaMailSender mailSender;
    
    public void setMailSender(JavaMailSender mailSender) {
        this.mailSender = mailSender;
    }

    public void placeOrder(final Order order) {

        // Do the business calculations...

        // Call the collaborators to persist the order...
        
        MimeMessagePreparator preparator = new MimeMessagePreparator() {
        
            public void prepare(MimeMessage mimeMessage) throws Exception {
        
                mimeMessage.setRecipient(Message.RecipientType.TO, 
                        new InternetAddress(order.getCustomer().getEmailAddress()));
                mimeMessage.setFrom(new InternetAddress("[email protected]"));
                mimeMessage.setText(
                    "Dear " + order.getCustomer().getFirstName() + " "
                        + order.getCustomer().getLastName()
                        + ", thank you for placing order. Your order number is "
                        + order.getOrderNumber());
            }
        };
        try {
            this.mailSender.send(preparator);
        }
        catch (MailException ex) {
            // simply log it and go on...
            System.err.println(ex.getMessage());            
        }
    }
}
[Note]Note

The mail code is a crosscutting concern and could well be a candidate for refactoring into a custom Spring AOP aspect, which then could be executed at appropriate joinpoints on the OrderManager target.

The Spring Framework's mail support ships with two MailSender implementations. The standard JavaMail implementation and the implementation on top of Jason Hunter's MailMessage class that is included in the com.oreilly.servlet package. Please refer to the relevant Javadocs for more information.