Java 实现 SMTP 协议邮件发送：完整实战指南

<dependency>
    <groupId>com.sun.mail</groupId>
    <artifactId>javax.mail</artifactId>
    <version>1.6.2</version>
</dependency>

import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.util.Properties;

public class SmtpMailSender {

    private static final String SMTP_HOST = "smtp.qq.com";
    private static final String SMTP_PORT = "587";
    private static final String USERNAME = "your_email@qq.com";
    private static final String AUTH_CODE = "your_auth_code"; // 授权码，非登录密码

    /**
     * 发送简单文本邮件
     * @param recipient 收件人地址
     * @param subject   邮件主题
     * @param content   邮件正文
     */
    public void sendTextEmail(String recipient, String subject, String content) {
        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.host", SMTP_HOST);
        props.put("mail.smtp.port", SMTP_PORT);
        props.put("mail.smtp.starttls.enable", "true");

        Session session = Session.getInstance(props, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(USERNAME, AUTH_CODE);
            }
        });
        // 生产环境建议关闭 debug
        session.setDebug(false);

        try {
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress(USERNAME));
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(recipient));
            message.setSubject(subject);
            message.setText(content);
            Transport.send(message);
            System.out.println("邮件发送成功: " + recipient);
        } catch (MessagingException e) {
            System.err.println("邮件发送失败: " + e.getMessage());
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        new SmtpMailSender().sendTextEmail(
            "recipient@example.com", 
            "体系架构验证测试", 
            "这是一封通过 SMTP 协议发送的测试邮件。"
        );
    }
}

import javax.mail.*;
import javax.mail.internet.*;
import java.io.File;
import java.util.Properties;

public class AdvancedMailSender {

    public void sendHtmlWithAttachment(String recipient, String subject, String htmlContent, File attachment) {
        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.host", "smtp.qq.com");
        props.put("mail.smtp.port", "465");
        props.put("mail.smtp.ssl.enable", "true");

        Session session = Session.getInstance(props, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication("your_email@qq.com", "your_auth_code");
            }
        });

        try {
            MimeMessage message = new MimeMessage(session);
            message.setFrom(new InternetAddress("your_email@qq.com"));
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(recipient));
            message.setSubject(subject);

            // 构建多部分内容
            MimeMultipart multipart = new MimeMultipart();

            // HTML 正文部分
            MimeBodyPart htmlPart = new MimeBodyPart();
            htmlPart.setContent(htmlContent, "text/html; charset=utf-8");
            multipart.addBodyPart(htmlPart);

            // 附件部分
            if (attachment != null && attachment.exists()) {
                MimeBodyPart attachmentPart = new MimeBodyPart();
                attachmentPart.attachFile(attachment);
                attachmentPart.setFileName(MimeUtility.encodeText(attachment.getName()));
                multipart.addBodyPart(attachmentPart);
            }

            message.setContent(multipart);
            Transport.send(message);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}