Utility class for HTML form decoding. This class contains static methods
for decoding a String from the
application/x-www-form-urlencoded
MIME format.
To conversion process is the reverse of that used by the URLEncoder class. It is assumed
that all characters in the encoded string are one of the following:
"a
" through "z
",
"A
" through "Z
",
"0
" through "9
", and
"-
", "_
",
".
", and "*
". The
character "%
" is allowed but is interpreted
as the start of a special escaped sequence.
The following rules are applied in the conversion:
- The alphanumeric characters "
a
" through
"z
", "A
" through
"Z
" and "0
"
through "9
" remain the same.
- The special characters "
.
",
"-
", "*
", and
"_
" remain the same.
- The plus sign "
+
" is converted into a
space character "
" .
- A sequence of the form "
%xy
" will be
treated as representing a byte where xy is the two-digit
hexadecimal representation of the 8 bits. Then, all substrings
that contain one or more of these byte sequences consecutively
will be replaced by the character(s) whose encoding would result
in those consecutive bytes.
The encoding scheme used to decode these characters may be specified,
or if unspecified, the default encoding of the platform will be used.
There are two possible ways in which this decoder could deal with
illegal strings. It could either leave illegal characters alone or
it could throw an IllegalArgumentException
.
Which approach the decoder takes is left to the
implementation.