发送邮件报错javax.activation.UnsupportedDataTypeException: no object DCH for MIME type text/plain; charset=UTF-8

用javamail发送附件出错：javax.activation.UnsupportedDataTypeException: no object DCH for MIME type text/plain; charset=UTF-8
javax.activation.UnsupportedDataTypeException: no object DCH for MIME type multipart

在Transport.send 语句执行发送前增加以下代码：

MailcapCommandMap mc = (MailcapCommandMap)CommandMap.getDefaultCommandMap();
mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html");
mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml");
mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain");
mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed");
mc.addMailcap("message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822");
CommandMap.setDefaultCommandMap(mc);
Thread.currentThread().setContextClassLoader(getClass().getClassLoader());