环境准备
Spring的邮件模块底层依赖于JavaMail，它主要目的是为应用提供一个便捷有用的发邮件工具包。邮件模块的代码在spring-context-support的jar包里，所在的package为org.springframework.mail。
Maven的pom.xm需要添加javax.mail jar包的依赖
<dependency>
<groupId>com.sun.mail</groupId>
<artifactId>javax.mail</artifactId>
<version>1.5.6</version>
</dependency>
如果spring环境里没有加入spring-context-support，也需要添加到依赖里。
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>4.3.9.RELEASE</version>
</dependency>
核心接口和类
在org.springframework.mail package下有几个核心的接口：
- MailSender：发邮件的核心接口
- MailMessage：表示邮件模型的接口，包含to，from等等，Spring提供里一个SimpleMailMessage类实现此接口，用于发送简单的邮件内容。
- JavaMailSender：使用JavaMail相关类的发送邮件类。其默认实现类为JavaMailSenderImpl
- MailException：邮件异常的*类
使用MailSender和SimpleMailMessage发送简单的邮件
public class MailSenderService {
private MailSender mailSender;
private SimpleMailMessage templateMessage;
public void setMailSender(MailSender mailSender) {
this.mailSender = mailSender;
}
public void setTemplateMessage(SimpleMailMessage templateMessage) {
this.templateMessage = templateMessage;
}
public void sendSimpleMail(String to,String mailContent) {
SimpleMailMessage msg = new SimpleMailMessage(this.templateMessage); //接收模板信息
msg.setTo(to);
msg.setText(mainContent);
try{
this.mailSender.send(msg);
} catch (MailException ex) {
System.err.println(ex.getMessage());
}
}
}
xml配置
<bean class="org.springframework.mail.javamail.JavaMailSenderImpl">
<property name="host" value="${mail.host}"/>
<property name="username" value="${mail.username}"></property>
<property name="password" value="${mail.password}"></property>
</bean>
<!-- 配置发邮件的模板，设置了from，主题 -->
<bean class="org.springframework.mail.SimpleMailMessage">
<property name="from" value="${mail.from}"/>
<property name="subject" value="${mail.defaultSubject}"/>
</bean>
<bean class="com.mycompany.service.MailSenderService ">
<property name="mailSender" ref="mailSender"/>
<property name="templateMessage" ref="templateMessage"/>
</bean>
使用JavaMailSender和MimeMessagePreparator发送邮件
使用MailSender和SimpleMailMessage只能文本这些简单的邮件，如果需要发送html或者添加附件，我们需要使用JavaMail的相关接口和类。Spring邮件模块提供JavaMailSender和MimeMessagePreparator两个类，它们暴露了JavaMail的MimeMessage用于发送复杂的邮件内容。
public class MailSenderService {
private JavaMailSender mailSender;
public void setMailSender(JavaMailSender mailSender) {
this.mailSender = mailSender;
}
public void sendMail(String from,String to,String mailContent) {
MimeMessagePreparator preparator = new MimeMessagePreparator() {
public void prepare(MimeMessage mimeMessage) throws Exception {
mimeMessage.setRecipient(Message.RecipientType.TO,
new InternetAddress(to));
mimeMessage.setFrom(new InternetAddress(from));
mimeMessage.setText(text);
}
};
try{
this.mailSender.send(preparator );
} catch (MailException ex) {
System.err.println(ex.getMessage());
}
}
}
MimemessagePreparator接口提供了prepare方法用于暴露JavaMail的MimeMessage，这样我们就可以对邮件内容做一些灵活的定制。
使用MimeMessageHelper
如果觉得直接使用JavaMail的MimeMessage设置邮件很麻烦，Spring提供了MimeMessageHelper类来封装对MimeMessage的操作。
上面的例子可以改为:
public class MailSenderService {
private JavaMailSender mailSender;
public void setMailSender(JavaMailSender mailSender) {
this.mailSender = mailSender;
}
public void sendMail(String to,String mailContent) {
MimeMessage message = sender.createMimeMessage(); //现创建MimeMesssage
MimeMessageHelper helper = new MimeMessageHelper(message);// 对MimeMessage包装
helper.setTo(to);
helper.setText(mailContent);
try{
this.mailSender.send(message); //最后发送的还是MimeMessage
} catch (MailException ex) {
System.err.println(ex.getMessage());
}
}
}
发送附件
使用JavaMail的MimeMessage可以发送丰富的邮件内容，如附件。这里基于MimeMessageHelper实现发送附件（当然，你也可以直接操作MimeMessage发送附件）。
public class MailSenderService {
private JavaMailSender mailSender;
public void setMailSender(JavaMailSender mailSender) {
this.mailSender = mailSender;
}
public void sendMail(String to,String mailContent,File attachment) {
MimeMessage message = sender.createMimeMessage(); //现创建MimeMesssage
MimeMessageHelper helper = new MimeMessageHelper(message);// 对MimeMessage包装
helper.setTo(to);
helper.setText(mailContent);
FileSystemResource file = new FileSystemResource(attachment);
helper.addAttachment(attachment.getName(), file);//添加附件
try{
this.mailSender.send(message); //最后发送的还是MimeMessage
} catch (MailException ex) {
System.err.println(ex.getMessage());
}
}
}
发送html
MimeMessageHelper发送html的设置很简单，如下：
public class MailSenderService {
private JavaMailSender mailSender;
public void setMailSender(JavaMailSender mailSender) {
this.mailSender = mailSender;
}
public void sendHtmlMail(String to,String html) {
MimeMessage message = sender.createMimeMessage(); //现创建MimeMesssage
MimeMessageHelper helper = new MimeMessageHelper(message);// 对MimeMessage包装
helper.setTo(to);
helper.setText(html,true); //只要对setText的第二个参数设置为true即可
try{
this.mailSender.send(message); //最后发送的还是MimeMessage
} catch (MailException ex) {
System.err.println(ex.getMessage());
}
}
}
处理乱码
如果发送中文相关内容，你可能会碰到乱码的情况。有几个地方会出现乱码：from,subject和邮件内容
下面以utf8编码为例
- 内容：在构建MimeMessageHelper设置编码格式，(mimeMessage,"utf8");
- from：使用MimeMessageHelper的setFrom(InternetAddress)方法，对InternetAddress设置utf8。
- subject：使用MimeUtility对主题编码，MimeUtility.encodeWord(subject, "UTF-8", "Q")
示例
MimeMessageHelper message = new MimeMessageHelper(mimeMessage,"utf8");
message.setTo(to);
message.setFrom(new InternetAddress(from,personName,"UTF-8"));
message.setSubject(MimeUtility.encodeWord(subject, "UTF-8", "Q"));