title: Flex SDK 3.5 - Check file mimetype
body: <p>Is there a way to get a file's mimetype in Flex SDK 3.5 without using its extension? </p>
  
  <p>I need to validate if an uploaded file is of a certain kind. This is for images, or documents (PDF, ODT, etc.)</p>
  
  <p>All the solutions I've found are by checking its extension. What if I rename a .odt file as a .jpg? Then I can upload it as an image...</p>
  
  <p>I should add, we are using an <strong>AIR desktop client</strong> and a Java EE server. File checking is solved on the Java side, but the idea is not to go to the server, validate the file so if it's not valid, there's no network traffic at all.</p>