使用javamail生成带附件的html邮件

一般来说，带附件并且有图片的html的mime邮件形如以下的格式：

 multipart/mixed

    multipart/related

        multipart/alternative

但JavaMail的FAQ没有详细解释如何发送这种多重嵌套multipart的mime邮件。关键是设置content-type为"message/rfc822",见下面示例代码的黑体部分。

public void createMail() {

 ......

 //这里只示例生成Multipart的代码，其他代码请参考JavaMail的相关文档

 Multipart mmp = null;

 mmp = getHtmlPart(plaintext, html);

 mmp = getRelatedPart(mmp, image);

 mmp = getMixedPart(mmp, attachment);

 ......

}

private Multipart getHtmlPart(String plaintext, String html) throws MessagingException {
 MimeMultipart mmp_alt = new MimeMultipart("alternative");
 MimeBodyPart mbp_text = new MimeBodyPart();
 mbp_text.setContent(plaintext, "text/plain;charset=UTF-8");
 mmp_alt.addBodyPart(mbp_text);
 MimeBodyPart mbp_html = new MimeBodyPart();
 mbp_html.setContent(html, "text/html;charset=UTF-8");
 mmp_alt.addBodyPart(mbp_html);

 return mmp_alt;

}

private Multipart getRelatedPart(Multipart aPart, String imagesPath) throws MessagingException, UnsupportedEncodingException {

 MimeMultipart mmp = new MimeMultipart("related");

 MimeBodyPart mbp = new MimeBodyPart();
 mbp.setContent(aPart, "message/rfc822");
 mmp.addBodyPart(mbp);

 String[] imageFiles = imagesPath.split(",");
 if (imageFiles.length != 0) {
  for (String file : imageFiles) {
   MimeBodyPart mbp_file = new MimeBodyPart();
   FileDataSource fds = new FileDataSource(file);
    mbp_file.setDataHandler(new DataHandler(fds));
   mbp_file.setFileName(MimeUtility.encodeText(fds.getName(), "gbk", "B"));
   File f = new File(file);
   mbp_file.setContentID("<" + f.getName() + ">");
   mmp.addBodyPart(mbp_file);
  }
 }
 return mmp;
}

private Multipart getMixedPart(Multipart aPart, String attachPath) throws MessagingException, IOException {
 MimeMultipart mmp = new MimeMultipart("mixed");

 MimeBodyPart mbp = new MimeBodyPart();
 mbp.setContent(aPart, "message/rfc822");
 mmp.addBodyPart(mbp);

 String[] files = attachPath.split(",");
 if (files.length != 0) {
  for (String file : files) {
   MimeBodyPart mbp_file = new MimeBodyPart();
   mbp_file.attachFile(file);
   mbp_file.setHeader("Content-Transfer-Encoding", "base64");
   mmp.addBodyPart(mbp_file);
  }
 }

 return mmp;
}