[Java] JavaMail 发送带图片的 html 格式的邮件

JavaMail 发送的邮件正文和附件是相互独立的，但是内置图片需要定位图片在正文中的位置，所以内置图片和邮件正文是互相依赖的。

发送带附件的邮件可参考 JavaMail 发送 html 格式、带附件的邮件。

发送纯文本的邮件可参照 JavaMail 简单案例。

具体例子

EmailHelper, Email 的帮助类，向帮助类提供 SMTP 服务器域名、用户名、密码、发送人邮箱、收件人邮箱、邮件主题、html 格式的内容、图片的路径，便可发送一份内置图片的邮件。在创建 MimeMultipart 时， 需要传入参数 related，并在正文中声明图片的位置。

SendEmailDemo, 演示发送邮件。

EmailHelper.java

package mail;

import java.util.Properties;

import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.BodyPart;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;

public class EmailHelper {
    
    private String host;
    private String username;
    private String password;
    private String from;
    
    private String to;
    private String subject;
    private String htmlContent;
    private String imagePath;
    
    public EmailHelper(String host, String username, String password, String from) throws AddressException, MessagingException{
        this.host = host;
        this.username = username;
        this.password = password;
        this.from = from;
    }
    
    public void sendWithImage() throws Exception {

        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.host", host);

        final String username1 = username;
        final String password1 = password;

        Session session = Session.getInstance(props, new javax.mail.Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(username1, password1);
            }
        });

        Message message = new MimeMessage(session);

        message.setFrom(new InternetAddress(from));

        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to));

        message.setSubject(subject);

        Multipart multipart = new MimeMultipart("related");

        System.out.println(" html ");
        BodyPart htmlPart = new MimeBodyPart();
        htmlContent = "<img src="cid:image">" + htmlContent;
        htmlPart.setContent(htmlContent, "text/html");
        multipart.addBodyPart(htmlPart);
        
        System.out.println(" image ");
        System.out.println("image path : " + imagePath);
        BodyPart imgPart = new MimeBodyPart();
        DataSource fds = new FileDataSource(this.imagePath);

        imgPart.setDataHandler(new DataHandler(fds));
        imgPart.setHeader("Content-ID", "<image>");

        multipart.addBodyPart(imgPart);
        message.setContent(multipart);
        Transport.send(message);

        System.out.println(" Sent -| ");
    }

    public void setTo(String to) {
        this.to = to;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }

    public void setHtmlContent(String htmlContent) {
        this.htmlContent = htmlContent;
    }
    
    public String getImagePath() {
        return imagePath;
    }

    public void setImagePath(String imagePath) {
        this.imagePath = imagePath;
    }
}

SendEmailDemo.java

public class SendEmailDemo {
    
    public static void main(){
        
        String host = "smtp.163.com";　　　　　　　　// use your smtp server host

        final String username = "sender@163.com"; // use your username
        final String password = "password"; 　　// use your password

        String from = "sender@163.com"; 　　　　// use your sender email address

        String to = "reciever@foxmail.com";　　// use your reciever email address
        try {
            EmailHelper emailHelper = new EmailHelper(host, username, password, from);
            emailHelper.setTo(to);
            emailHelper.setSubject("subject ttt test");
            emailHelper.setHtmlContent("<h1> This is html </h1>");
            emailHelper.setImagePath("/Users/grs/Documents/Java/mavenEmail/test/src/main/resource/promises.png");
            
            emailHelper.send();
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

参考资料

JavaMail API - Sending Email With Inline Imagess