You may also get mime type of a file stored on web.

Java Code:
import java.net.*;

public class FileUtils{
  public static String getMimeType(String fileUrl)
    throws java.io.IOException, MalformedURLException 
  {
    String type = null;
    URL u = new URL(fileUrl);
    URLConnection uc = null;
    uc = u.openConnection();
    type = uc.getContentType();
    return type;
  }

  public static void main(String args[]) throws Exception {
    System.out.println(FileUtils.getMimeType("file://c:/temp/test.TXT"));
    // output :  text/plain
  }
}