Java Reference
In-Depth Information
• The plus sign “+”/“%20” is converted into a space character “ ”.
• Asequenceoftheform%
xy
willbetreatedasrepresentingabytewhere
xy
is
thetwo-digithexadecimalrepresentationofthe8bits.Then,allsubstringscon-
tainingoneormoreofthesebytesequencesconsecutivelywillbereplacedby
the character(s) whose encoding would result in those consecutive bytes. The
encoding scheme used to decode these characters may be specified; when un-
specified, the platform's default encoding is used.
URLDecoder
declares the following class method for decoding an encoded string:
String decode(String s, String enc)
This method decodes an
application/x-www-form-urlencoded
string us-
ing the specified encoding scheme. The supplied encoding is used to determine what
charactersarerepresentedbyanyconsecutivesequencesoftheform%
xy
.
Unsuppor-
tedEncodingException
is thrown when
enc
's value isn't supported.
Therearetwopossiblewaysinwhichthedecodercoulddealwithillegallyencoded
strings.Itcouldeitherleaveillegalcharactersaloneoritcouldthrow
IllegalArgu-
mentException
. Which approach the decoder takes is left to the implementation.
Note
The World Wide Web Consortium Recommendation (
ht-
schemefor
encode()
and
decode()
.Notdoingsomayintroduceincompatibilities.
I've created an application that demonstrates
URLEncoder
and
URLDecoder
in
the context of the previous
"the string ü@foo-bar"
and
"the+string+%c3%bc%40foo-bar"
example.
Listing 9-9
presents the applica-
tion's source code.
Listing 9-9.
Encoding and decoding an encoded string
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
class EncDec
{
public static void main(String[] args) throws Unsuppor-
