Gets the named parameter value as a boolean, with true indicated by
"true", "on", or "yes" in any letter case, false indicated by "false",
"off", or "no" in any letter case.
Returns the original filesystem name of the specified file (before any
renaming policy was applied), or null if the file was not included in
the upload.
Gets a reference to the given resource within the given context,
making sure not to serve the contents of WEB-INF, META-INF, or to
display .jsp file source.
Returns the value of the parameter in as a string (using the
parser-specified encoding to convert from bytes) or the empty string
if the user entered no value for this parameter.