Este es un ejemplo:
/**
* The query parameters for this servlet are:
* <ol>
* <li>data, required, example: "1234567890"
* <li>type, optional, examples: "Code128A", "Code128B", "Code128C", if left blank will default to Code 128 B.
* Note that the type here must be <b>exactly</b> the name of one of the createX methods on BarcodeFactory without
* the "create" prefix. This is case sensitive.
* <li>appid, required for UCC128 type, ignored for all other types - specifies the application identifier to use with
* the UCC128 barcode, example: "420" for a US postal service barcode
* <li>width, optional, in pixels
* <li>height, optional, in pixels
* <li>resolution, optional, in dpi
* <li>headless, optional, set to "false" to force non-headless mode for the servlet - default is "true"
* <li>drawText, optional and only takes effect if headless is "false", set to "false" for no text
* </ol>
*
* <p>Example URL: <code>http://hostname:80/myapp/BarcodeServlet?data=12345&type=Code128A</code>
* </p>
*
* <p>Contributed by Robert Chou <rchou at users.sourceforge.net></p>