Setting MimeType for Unknown Attachment

Question

Hi,
I have a file called FileDataSource (implements DataSource) which does the job of setting / Checking Mime Type (Sending / received) and also getting Input Stream / Output Stream for the same.
Sending:
When I call this class from out side I pass the complete file name as parameter to the constructor. I have a method inside of it which extracts the file extension and depending on that it returns the content Type. Previously I was checking it manually for each known extensions now I have an XML file with all the mime mappings. Give the extension it returns the content Type. What if the extension is unknown type????? What should I return as content Type?????
Note: In the following method I am returning text/plain if it is un-known. I don't think this correct way of doing. Any HELP could be appreciated.
i.e
     public String getContentType(){
     int i = name.lastIndexOf(".");
     String s = name.substring(i+1);
     s = s.trim();
     cat.debug("          getContentType()----------->extension =="+s);
     if(s.equalsIgnoreCase("zip")){
     cat.info("          ******* ZIP ******");
          return "application/x-bolero-doc";
     else if(s.equalsIgnoreCase("doc")){
     cat.info("          ******* DOC ******");
          return "application/msword";
     else if(s.equalsIgnoreCase("txt")){
     cat.info("          ******* TXT ******");
          return "text/plain";
     else if(s.equalsIgnoreCase("htm")||s.equalsIgnoreCase("html")){
     cat.info("          ******* HTM ******");
          return "text/html";
     else if(s.equalsIgnoreCase("xls")){
     cat.info("          ******* XLS ******");
          return "application/excel";
     else if(s.equalsIgnoreCase("pdf")){
cat.info("          ******* pdf ******");
return "application/pdf";
     else {
     cat.info("          ******* ELSE part(getContentType()) ******");
          return "text/plain";

Answer 1

Thanks I just got that and i implemented that. I saw this in the message generated by Outlook for .BAT file.
Once again thanks for the reply.