Spring邮件抽象层的主要包为org.springframework.mail。它包括了发送电子邮件的主要接口MailSender，和值对象SimpleMailMessage，它封装了简单邮件的属性如from, to,cc, subject,text。 包里还包含一棵以MailException为根的checked Exception继承树，它们提供了对底层邮件系统异常的高级别抽象。 要获得关于邮件异常层次的更丰富的信息，请参考Javadocs。
为了使用JavaMail中的一些特色, 比如MIME类型的信件, Spring提供了MailSender的一个子接口, 即org.springframework.mail.javamail.JavaMailSender。Spring还提供了一个回调接口org.springframework.mail.javamail.MimeMessagePreparator, 用于准备JavaMail的MIME信件。
public interface MailSender {
/**
* Send the given simple mail message.
* @param simpleMessage message to send
* @throws MailException in case of message, authentication, or send errors
*/
public void send(SimpleMailMessage simpleMessage) throws MailException;
/**
* Send the given array of simple mail messages in batch.
* @param simpleMessages messages to send
* @throws MailException in case of message, authentication, or send errors
*/
public void send(SimpleMailMessage[] simpleMessages) throws MailException;
}public interface JavaMailSender extends MailSender {
/**
* Create a new JavaMail MimeMessage for the underlying JavaMail Session
* of this sender. Needs to be called to create MimeMessage instances
* that can be prepared by the client and passed to send(MimeMessage).
* @return the new MimeMessage instance
* @see #send(MimeMessage)
* @see #send(MimeMessage[])
*/
public MimeMessage createMimeMessage();
/**
* Send the given JavaMail MIME message.
* The message needs to have been created with createMimeMessage.
* @param mimeMessage message to send
* @throws MailException in case of message, authentication, or send errors
* @see #createMimeMessage
*/
public void send(MimeMessage mimeMessage) throws MailException;
/**
* Send the given array of JavaMail MIME messages in batch.
* The messages need to have been created with createMimeMessage.
* @param mimeMessages messages to send
* @throws MailException in case of message, authentication, or send errors
* @see #createMimeMessage
*/
public void send(MimeMessage[] mimeMessages) throws MailException;
/**
* Send the JavaMail MIME message prepared by the given MimeMessagePreparator.
* Alternative way to prepare MimeMessage instances, instead of createMimeMessage
* and send(MimeMessage) calls. Takes care of proper exception conversion.
* @param mimeMessagePreparator the preparator to use
* @throws MailException in case of message, authentication, or send errors
*/
public void send(MimeMessagePreparator mimeMessagePreparator) throws MailException;
/**
* Send the JavaMail MIME messages prepared by the given MimeMessagePreparators.
* Alternative way to prepare MimeMessage instances, instead of createMimeMessage
* and send(MimeMessage[]) calls. Takes care of proper exception conversion.
* @param mimeMessagePreparators the preparator to use
* @throws MailException in case of message, authentication, or send errors
*/
public void send(MimeMessagePreparator[] mimeMessagePreparators) throws MailException;
}public interface MimeMessagePreparator {
/**
* Prepare the given new MimeMessage instance.
* @param mimeMessage the message to prepare
* @throws MessagingException passing any exceptions thrown by MimeMessage
* methods through for automatic conversion to the MailException hierarchy
*/
void prepare(MimeMessage mimeMessage) throws MessagingException;
}假设某个业务接口名为 OrderManager:
public interface OrderManager {
void placeOrder(Order order);
}同时有一个用例为：需要生成带有订单号的email信件, 并向客户发送该订单。 为此，我们会使用MailSender接口和SimpleMailMessage类。
请注意,通常情况下,我们在业务代码中使用接口而让Spring ioc容器负责组装我们需要的合作者。
以下是OrderManager的实现:
import org.springframework.mail.MailException;
import org.springframework.mail.MailSender;
import org.springframework.mail.SimpleMailMessage;
public class OrderManagerImpl implements OrderManager {
private MailSender mailSender;
private SimpleMailMessage message;
public void setMailSender(MailSender mailSender) {
this.mailSender = mailSender;
}
public void setMessage(SimpleMailMessage message) {
this.message = message;
}
public void placeOrder(Order order) {
// Do the business calculations...
// Call the collaborators to persist the order...
//Create a thread safe "sandbox" of the message
SimpleMailMessage msg = new SimpleMailMessage(this.message);
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{
mailSender.send(msg);
}
catch(MailException ex) {
//log it and go on
System.err.println(ex.getMessage());
}
}
}上面的代码的bean定义应该是这样的:
<bean id="mailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl"> <property name="host" value="mail.mycompany.com"/> </bean> <bean id="mailMessage" class="org.springframework.mail.SimpleMailMessage"> <property name="from" value="customerservice@mycompany.com"/> <property name="subject" value="Your order"/> </bean> <bean id="orderManager" class="com.mycompany.businessapp.support.OrderManagerImpl"> <property name="mailSender" ref="mailSender"/> <property name="message" ref="mailMessage"/> </bean>
下面是OrderManager接口的实现，使用了MimeMessagePreparator回调接口。 请注意这里的mailSender属性的类型为JavaMailSender,这样做是为了能够使用JavaMail的MimeMessage：
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 OrderManagerImpl 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 MessagingException {
mimeMessage.setRecipient(Message.RecipientType.TO,
new InternetAddress(order.getCustomer().getEmailAddress()));
mimeMessage.setFrom(new InternetAddress("mail@mycompany.com"));
mimeMessage.setText(
"Dear "
+ order.getCustomer().getFirstName()
+ order.getCustomer().getLastName()
+ ", thank you for placing order. Your order number is "
+ order.getOrderNumber());
}
};
try {
mailSender.send(preparator);
}
catch (MailException ex) {
//log it and go on
System.err.println(ex.getMessage());
}
}
}如果你想获得JavaMail MimeMessage的全部能力，你可以使用MimeMessagePreparator。
![[Note]](../images/admons/note.png) | Note |
|---|---|
以上的邮件代码是一个横切关注点，是重构为定制SpringAOP advice的完美候选者,这样就可以在目标对象OrderManager合适的joinpoint中运行。请参阅Chapter 6, 使用Spring进行面向切面编程（AOP）章节。 | |
Spring直接提供两种MailSender的实现:标准的JavaMail实现,和基于Jason Hunter 编写的MailMessage类之上的实现,后者位于http://servlets.com/cos (com.oreilly.servlet)。进一步的资料请查阅相关Javadocs。
org.springframework.mail.javamail.MimeMessageHelper是处理JavaMail邮件常用的顺手组件之一。它可以让你摆脱繁复的javax.mail.internetAPI类。下面是一些通常的场景：
使用MimeMessageHelper来创建和发送 MimeMessage消息是非常容易的:
// of course you would use DI in any real-world cases
JavaMailSenderImpl sender = new JavaMailSenderImpl();
sender.setHost("mail.host.com");
MimeMessage message = sender.createMimeMessage();
MimeMessageHelper helper = new MimeMessageHelper(message);
helper.setTo("test@host.com");
helper.setText("Thank you for ordering!");
sender.send(message);Email允许添加附件，也允许在multipart信件中内嵌资源。内嵌资源可能是你在信件中希望使用的图像，或者样式表，但是又不想把它们作为附件。下面的例子演示如何使用MimeMessageHelper来发送带有内嵌图像的email。
JavaMailSenderImpl sender = new JavaMailSenderImpl();
sender.setHost("mail.host.com");
MimeMessage message = sender.createMimeMessage();
// use the true flag to indicate you need a multipart message
MimeMessageHelper helper = new MimeMessageHelper(message, true);
helper.setTo("test@host.com");
// use the true flag to indicate the text included is HTML
helper.setText("<html><body><img src='cid:identifier1234'></body></html>", true);
// let's include the infamous windows Sample file (this time copied to c:/)
FileSystemResource res = new FileSystemResource(new File("c:/Sample.jpg"));
helper.addInline("identifier1234", res);
// if you would need to include the file as an attachment, use
// the various addAttachment() methods on the MimeMessageHelper
sender.send(message);![[Warning]](../images/admons/warning.png) | Warning |
|---|---|
如你所见，嵌入式资源使用Content-ID(上例中是identifier1234)来插入到mime信件中去。你加入文本或者资源的顺序是非常重要的。首先，你加入文本，随后是资源。如果你弄反了顺序，它将无法正常运作！ | |