使用javamail發送包含圖片的html格式郵件

使用JavaMail可以很方便的發送html格式的郵件，只需要將content-type設置為"text/html"即可。要在郵件中包含圖片簡單辦法是使用image標簽，src指向服務器上圖片的位置。但是有些郵件客戶端會把是否包含有服務器端圖片作為垃圾郵件的判斷機制。我們可以將圖片內嵌到郵件中，然后用cid加content-id引用內嵌的圖片。

import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;

import java.util.Properties;

class SimpleMail2 {
    public static void main(String[] args) throws Exception{
        System.out.println("Sending mail...");
        Properties props = new Properties();
        props.setProperty("mail.transport.protocol", "smtp");
        props.setProperty("mail.host", "smtp.mymailserver.com");
        props.setProperty("mail.user", "myuser");
        props.setProperty("mail.password", "mypwd");

        Session mailSession = Session.getDefaultInstance(props, null);
        mailSession.setDebug(true);
        Transport transport = mailSession.getTransport();

        MimeMessage message = new MimeMessage(mailSession);
        message.setSubject("HTML  mail with images");
        message.setFrom(new InternetAddress("me@sender.com"));
        message.addRecipient(Message.RecipientType.TO,
             new InternetAddress("you@receiver.com"));

        //
        // This HTML mail have to 2 part, the BODY and the embedded image
        //
        MimeMultipart multipart = new MimeMultipart("related");

        // first part  (the html)
        BodyPart messageBodyPart = new MimeBodyPart();
        String htmlText = "<H1>Hello</H1><img src=\"cid:image\">";
        messageBodyPart.setContent(htmlText, "text/html");

        // add it
        multipart.addBodyPart(messageBodyPart);

        // second part (the image)
        messageBodyPart = new MimeBodyPart();
        DataSource fds = new FileDataSource
          ("C:\\images\\jht.gif");
        messageBodyPart.setDataHandler(new DataHandler(fds));
        messageBodyPart.setHeader("Content-ID","<image>");

        // add it
        multipart.addBodyPart(messageBodyPart);

        // put everything together
        message.setContent(multipart);

        transport.connect();
        transport.sendMessage(message,
            message.getRecipients(Message.RecipientType.TO));
        transport.close();
        }
}