What is getDocumetBase() ?

Question

and how it is different from getCodeBase()?

Answer 1

getDocumentBase() gets the URL of the document in which an applet is embedded.

getCodeBase() gets the base URL. This is the URL of the directory which contains the applet.

Source: http://stackoverflow.com/questions/23817796/how-do-you-use-getdocumentbase-and-getcodebase-correctly-in-java-applets

Remark: All credit to Braj from StackOverflow who has explained what you are looking for in a similar question there.