介绍

发送邮件是一个很常见的需求，如用户注册，用户密码修改，密码找回等。今天我们看一下使用JavaSE和Spring实现发送邮件的功能。

邮件协议

SMTP协议是基于TCP/IP的一个应用层协议，类似于HTTP，全称为 Simple Mail Transfer Protocol，译作简单邮件传输协议，它定义了邮件客户端软件与SMTP 服务器之间，以及 SMTP 服务器与 SMTP 服务器之间的通信规则。我们通过邮件客户端或程序发送邮件时就用到了该协议。

而 POP3 协议全称为 Post Office Protocol ，译作邮局协议，它定义了邮件客户端与 POP3服务器之间的通信规则。我们通过邮件客户端查看邮件时就用到了该协议。

IMAP(Internet Message Access Protocol)协议是对POP3协议的一种扩展，功能更强，作用类似。

发送前准备

发送前需要获取邮箱的授权码，以网易126邮箱为例

使用JavaSE发送简单邮件

添加maven依赖

com.sun.mail

javax.mail

1.6.2

发送邮件

public class Client {

public static void main(String[] args) throws Exception {

Properties props = new Properties();

//设置邮件地址

props.put("mail.smtp.host", "smtp.126.com");

//开启认证

props.put("mail.smtp.auth", "true");

Session session = Session.getDefaultInstance(props, null);

Transport transport = session.getTransport();

//用户名

String user = "xxx@126.com";

//授权码

String password = "xxx";

transport.connect(user, password);

//创建邮件消息

MimeMessage msg = new MimeMessage(session);

msg.setSentDate(new Date());

//邮件发送人

InternetAddress fromAddress = new InternetAddress(user, "邮件服务");

msg.setFrom(fromAddress);

//邮件接收人

String to = "xxx@163.com";

InternetAddress[] toAddress = new InternetAddress[]{new InternetAddress(to)};

msg.setRecipients(Message.RecipientType.TO, toAddress);

//邮件主题

msg.setSubject("测试邮件发送", "UTF-8");

//邮件内容和格式

msg.setContent("this is a test mail", "text/html;charset=UTF-8");

msg.saveChanges();

//发送

transport.sendMessage(msg, msg.getAllRecipients());

}

}

发送带附件的邮件

public class Client {

public static void main(String[] args) throws Exception {

Properties props = new Properties();

//设置邮件地址

props.put("mail.smtp.host", "smtp.126.com");

//开启认证

props.put("mail.smtp.auth", "true");

Session session = Session.getDefaultInstance(props, null);

Transport transport = session.getTransport();

//用户名

String user = "xxx@126.com";

//授权码

String password = "xxx";

transport.connect(user, password);

//创建邮件消息

MimeMessage msg = new MimeMessage(session);

msg.setSentDate(new Date());

//邮件发送人

InternetAddress fromAddress = new InternetAddress(user, "邮件服务");

msg.setFrom(fromAddress);

//邮件接收人

String to = "xxx@163.com";

InternetAddress[] toAddress = new InternetAddress[]{new InternetAddress(to)};

msg.setRecipients(Message.RecipientType.TO, toAddress);

//邮件主题

msg.setSubject("测试邮件发送", "UTF-8");

//内容和附件

Multipart multipart = new MimeMultipart();

//内容

BodyPart contentBodyPart = new MimeBodyPart();

contentBodyPart.setContent("this also is a test mail", "text/html;charset=UTF-8");

multipart.addBodyPart(contentBodyPart);

//附件

BodyPart fileBody = new MimeBodyPart();

DataSource source = new FileDataSource("D:/a.png");

fileBody.setDataHandler(new DataHandler(source));

fileBody.setFileName("测试附件.png");

multipart.addBodyPart(fileBody);

//邮件内容

msg.setContent(multipart);

msg.saveChanges();

//发送

transport.sendMessage(msg, msg.getAllRecipients());

}

}

使用Spring发送简单邮件

spring在原有的基础上又封装了一层，简化了开发。

org.springframework

spring-context-support

5.1.2.RELEASE

com.sun.mail

javax.mail

1.6.2

public class Client {

public static void main(String[] args) throws Exception {

JavaMailSender mailSender = createJavaMailSender();

//创建邮件消息

MimeMessage mimeMessage = mailSender.createMimeMessage();

MimeMessageHelper messageHelper = new MimeMessageHelper(mimeMessage);

//发送人

messageHelper.setFrom("xxx@126.com", "邮件服务");

//收件人

messageHelper.setTo("xxx@163.com");

//主题

messageHelper.setSubject("测试邮件发送");

//发送时间

messageHelper.setSentDate(new Date());

//发送内容

messageHelper.setText("this is a test mail by spring");

mailSender.send(mimeMessage);

}

private static JavaMailSender createJavaMailSender() {

JavaMailSenderImpl mailSender = new JavaMailSenderImpl();

mailSender.setDefaultEncoding(StandardCharsets.UTF_8.name());

String username = "xxx@126.com";

//设置用户名

mailSender.setUsername(username);

//设置授权码

mailSender.setPassword("xxx");

Properties props = new Properties();

//设置邮件地址

props.put("mail.smtp.host", "smtp.126.com");

//开启认证

props.put("mail.smtp.auth", "true");

mailSender.setJavaMailProperties(props);

return mailSender;

}

}

使用Spring发送带附件的邮件

public class Client {

public static void main(String[] args) throws Exception {

JavaMailSender mailSender = createJavaMailSender();

//创建邮件消息

MimeMessage mimeMessage = mailSender.createMimeMessage();

//multipart为true表示可以带附件

MimeMessageHelper messageHelper = new MimeMessageHelper(mimeMessage, true);

//发送人

messageHelper.setFrom("xxx@126.com", "邮件服务");

//收件人

messageHelper.setTo("xxx@163.com");

//主题

messageHelper.setSubject("测试邮件发送");

//发送时间

messageHelper.setSentDate(new Date());

//发送内容

messageHelper.setText("this is a test mail by spring");

//添加附件

messageHelper.addAttachment("测试附件.png", new FileDataSource("D:/a.png"));

mailSender.send(mimeMessage);

}

private static JavaMailSender createJavaMailSender() {

JavaMailSenderImpl mailSender = new JavaMailSenderImpl();

mailSender.setDefaultEncoding(StandardCharsets.UTF_8.name());

String username = "xxx@126.com";

//设置用户名

mailSender.setUsername(username);

//设置授权码

mailSender.setPassword("xxx");

Properties props = new Properties();

//设置邮件地址

props.put("mail.smtp.host", "smtp.126.com");

//开启认证

props.put("mail.smtp.auth", "true");

mailSender.setJavaMailProperties(props);

return mailSender;

}

}