java - Convert content-type from text/plain to text/html in an email with attachment -

i'm trying display email messages gotten server. prior letting know issue, take @ code:

public filemailextended getsinglemessage(integer filemailid) throws mailsystemexception, ioexception,         messagingexception, boserviceexception {     filemail email = retrieve(filemailid.intvalue());      mailerscopedef scope = email.gettype();     boolean outbound = email.getdirection() == emailconstants.direction_sent;     long uid = long.valueof(email.getuid());      string folder = null;     if (outbound) {         folder = configurationservice.getsentfolder(scope);     } else {         folder = configurationservice.getreadfolder(scope);     }      filemailconfig filemailconfig = getfilemailconfig(folder);     long uidvalidity = 0;     if (filemailconfig != null) {         uidvalidity = filemailconfig.getversionid();     }      imapfoldermanager ifm;     if (outbound) {         ifm = ((imapsender) configurationservice.getmailsender(scope)).getimapfoldermger();     } else {         ifm = configurationservice.getimapfoldermanagerreader(scope);     }      filemailextended emailextended = new filemailextended();     mapfilemailtofilemailextended(email, emailextended);     try {         imapmessage message = (imapmessage) ifm.getmessage(uid, uidvalidity);         if (message == null) {             logger.error("could not read message uid:" + uid + " server.");             return null;         }          internetaddress intadress = (internetaddress) message.getsender();         string unicodestring = intadress.tounicodestring().replace("\"", "");         emailextended.setfrom(unicodestring);         emailextended.setto(appendaddresses(message.getrecipients(recipienttype.to)));         emailextended.setcc(appendaddresses(message.getrecipients(recipienttype.cc)));         emailextended.setcci(appendaddresses(message.getrecipients(recipienttype.bcc)));         emailextended.setsubject(message.getsubject());          string content = "";          if (message.getcontent() instanceof string) {             content += (string) message.getcontent();         } else if (message.getcontent() instanceof multipart) {             multipart multipart = (multipart) message.getcontent();             stringbuffer buf = new stringbuffer();             (int x = 0; x < multipart.getcount(); x++) {                 bodypart bodypart = multipart.getbodypart(x);                 if (bodypart == null || bodypart.getcontenttype() == null) {                     continue;                 }                 if (bodypart.ismimetype(text_html)) {                     buf.append((string) bodypart.getcontent());                 } else if (bodypart.getcontent() instanceof multipart) {                     multipart multipart2 = (multipart) bodypart.getcontent();                     (int xx = 0; xx < multipart2.getcount(); xx++) {                         bodypart bodypart2 = multipart2.getbodypart(xx);                         if (bodypart2 != null && bodypart2.ismimetype("text/html") {                             buf.append((string) bodypart2.getcontent());                         }                     }                 }             }             content = buf.tostring();         }         emailextended.setcontent(content);          if (message.getcontent() instanceof multipart) {             multipart multipart = (multipart) message.getcontent();             (int = 0; < multipart.getcount(); i++) {                 bodypart bodypart = multipart.getbodypart(i);                 if (!part.attachment.equalsignorecase(bodypart.getdisposition())) {                     // dealing attachments                     continue;                 }                 emailextended.addattachmentnames(bodypart.getfilename());             }         }      } {         closefoldermanager(ifm);     }      return emailextended; } 

this code works fine when email doesn't have attachments. emailcontent, formatted in html, readable without efforts.
problem is, once email contains attachment file, nothing displayed.
discovered because of content-type, "text/plain" when sending message attachments when "text/html" simple mail. changed condition take in account content-type, result displayed is..uh..just raw text.
planned force content-type "text/html" code bodypart2.setheader("content-type", "text/html"); , ended exception. clue why content-type of email attachments has "text/plain"? googled it, no significant answers.
how can change it?
many thanks.

whether content text/plain or text/html has nothing whether or not message has attachments.

in cases, messages have multipart/alternative content contains both text/plain , text/html parts. in case can choose text/html part. this example code in javamail faq might help.

if message has text/plain part, it's format , display think best.