【Java Mail】 使用java mail发送邮件

465端口和587端口差异对比可参考：https://liaoxuefeng.com/books/java/spring/integration/javamail/index.html

 

 

特别注意写在最前面：

1.SMTP邮箱服务 有两个端口

SMTP 端口号（SSL）465
SMTP 端口号（starttls）587

所以，在发送邮件时，一定要注意 不同端口，配置Properties细节处的差异。
细节不正确，会导致
① null指针异常
② Transport.send(message)后线程卡死无响应

以下代码，就是以 465端口发送邮件的完整代码，特别注意标红部分。


2.properties.put("mail.transport.protocol", "smtp");
配置未指定，会导致 null指针异常

java.lang.NullPointerException: null
        at com.sun.mail.handlers.text_plain.writeTo(text_plain.java:133)
        at javax.activation.ObjectDataContentHandler.writeTo(DataHandler.java:889)
        at javax.activation.DataHandler.writeTo(DataHandler.java:317)
        at javax.mail.internet.MimeUtility.getEncoding(MimeUtility.java:340)
        at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1573)
        at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1172)
        at javax.mail.internet.MimeMultipart.updateHeaders(MimeMultipart.java:522)
        at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1531)
        at javax.mail.internet.MimeMessage.updateHeaders(MimeMessage.java:2271)
        at javax.mail.internet.MimeMessage.saveChanges(MimeMessage.java:2231)


3.properties.put("mail.smtp.ssl.enable", "false");
        properties.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
配置未指定，会导致 Transport.send(message); 执行后无响应，线程挂起

 

 

 

util核心代码：

import com.alibaba.fastjson.JSON;
import lombok.extern.slf4j.Slf4j;

import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.*;
import javax.mail.internet.*;
import java.io.File;
import java.util.Properties;

@Slf4j
public class MailUtils {

    public static void  sendMail() {
        // 邮件服务器配置
        String host = "smtp.XXX.cn"; // 邮件服务器地址
        String port = "465"; // 邮件服务器端口号
        String username = "marketingdata-noreply@XX.com"; // 发件人邮箱
        String password = "OLiafELfknqYtQ6x"; // 发件人邮箱密码


        // 邮件内容
        String to = "angel.sxd@XXX.com"; // 收件人邮箱
        String subject = "暂占邮件标题坑位之看我几分像从前";
        String body = "这是一封测试邮件，包含附件。";
        String attachmentPath = "/暂占邮件标题坑位之看我几分像从前.xlsx"; // 附件路径
        //List<String> filePaths  = ; //多个附件路径

        Properties properties = new Properties();
        properties.put("mail.transport.protocol", "smtp");
        properties.put("mail.smtp.host", host);
        properties.put("mail.smtp.socketFactory.port", port);
        properties.put("mail.smtp.auth", "true");
        properties.put("mail.smtp.starttls.enable", "true");
        properties.put("mail.smtp.ssl.enable", "false");
        properties.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");

        Session session = Session.getInstance(properties, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(username, password);
            }
        });
        session.setDebug(true);

        log.info("send mail info begin1  props:{} session:{}", JSON.toJSONString(properties), cn.hutool.json.JSONUtil.toJsonStr(session));
        try {
            // 创建邮件消息
            MimeMessage message = new MimeMessage(session);
            message.setFrom(new InternetAddress(username));
            message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
            message.setSubject(subject);

            // 创建邮件正文
            MimeBodyPart textPart = new MimeBodyPart();
            textPart.setText(body);

            // 创建单个附件
            MimeBodyPart attachmentPart = new MimeBodyPart();
            File attachmentFile = new File(attachmentPath);
            DataSource source = new FileDataSource(attachmentFile);
            attachmentPart.setDataHandler(new DataHandler(source));
            attachmentPart.setFileName(attachmentFile.getName());
　　　　　　　　
            
            
            
            // 创建多个附件
//            MimeBodyPart attachFileBodypart = new MimeBodyPart();
//            MimeMultipart attachFileMMP = new MimeMultipart("related");
//            if (!CollectionUtils.isEmpty(filePaths)) {
//                for (int i = 0; i < filePaths.size(); i++) {
//                    MimeBodyPart attachFileBody = new MimeBodyPart();
//                    FileDataSource fds = new FileDataSource(new File(filePaths.get(i)));// 附件文件
//                    attachFileBody.setDataHandler(new DataHandler(fds));// 得到附件本身并至入BodyPart
//                    // MimeUtility.encodeText()解决文件名乱码问题
//                    attachFileBody.setFileName(MimeUtility.encodeText(fds.getName()));// 得到文件名同样至入BodyPart
//                    attachFileMMP.addBodyPart(attachFileBody);// 放入BodyPart
//                }
//            }
//            attachFileBodypart.setContent(attachFileMMP, "text/html;charset=UTF-8");
            
            
            
            

            // 组合正文和附件
            Multipart multipart = new MimeMultipart();
            multipart.addBodyPart(textPart);
            multipart.addBodyPart(attachmentPart);
            //multipart.addBodyPart(attachFileBodypart);

            message.setContent(multipart);
            log.info("send mail info begin2  message:{} ", cn.hutool.json.JSONUtil.toJsonStr(message));
            // 发送邮件
            Transport.send(message);
            log.info("send mail info end  message:{} ", cn.hutool.json.JSONUtil.toJsonStr(message));
        } catch (AddressException e) {
            throw new RuntimeException(e);
        } catch (MessagingException e) {
            throw new RuntimeException(e);
        }
    }

}

 

 

邮件发送成功如图：