com.isti.util

Class URLRefDecoder

java.lang.Object

com.isti.util.URLRefDecoder

public class URLRefDecoder
extends java.lang.Object

Utility class for HTML form decoding. This class contains static methods for decoding a String from the application/x-www-form-urlencoded MIME format.

The 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.

Since:

1.2

Author:

Mark Chamness, Michael McCloskey

Field Summary

Fields

Modifier and Type	Field and Description
static java.nio.charset.Charset	DEFAULT_ENCODING The default encoding

Constructor Summary

Constructors

Constructor and Description
URLRefDecoder()

Method Summary

Modifier and Type	Method and Description
static boolean	decode(java.lang.Appendable out, java.lang.CharSequence cs, java.nio.charset.Charset charset) Decodes an application/x-www-form-urlencoded string using a specific Charset.
static java.lang.String	decode(java.lang.CharSequence cs) Decodes a x-www-form-urlencoded string.
static java.lang.String	decode(java.lang.CharSequence cs, java.nio.charset.Charset charset) Decodes an application/x-www-form-urlencoded string using a specific Charset.
static java.lang.String	decode(java.lang.CharSequence cs, java.lang.String enc) Decodes an application/x-www-form-urlencoded string using a specific encoding scheme.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_ENCODING

public static java.nio.charset.Charset DEFAULT_ENCODING

The default encoding

Constructor Detail

URLRefDecoder

public URLRefDecoder()

Method Detail

decode

public static boolean decode(java.lang.Appendable out,
                             java.lang.CharSequence cs,
                             java.nio.charset.Charset charset)
                      throws java.io.IOException

Decodes an application/x-www-form-urlencoded string using a specific Charset. The supplied charset is used to determine what characters are represented by any consecutive sequences of the form "%xy".

Note: The World Wide Web Consortium Recommendation states that UTF-8 should be used. Not doing so may introduce incompatibilities.

Parameters:

out - the output.

cs - the CharSequence to decode

charset - the given charset

Returns:

true if changed, false otherwise.

Throws:

java.lang.NullPointerException - if s or charset is null

java.lang.IllegalArgumentException - if the implementation encounters illegal characters

java.io.IOException - If an I/O error occurs.

See Also:

URLEncoder#encode(java.lang.String, java.nio.charset.Charset)

decode

public static java.lang.String decode(java.lang.CharSequence cs)

Decodes a x-www-form-urlencoded string. The UTF-8 encoding is used to determine what characters are represented by any consecutive sequences of the form "%xy".

Parameters:

s - the CharSequence to decode

Returns:

the newly decoded String

decode

public static java.lang.String decode(java.lang.CharSequence cs,
                                      java.nio.charset.Charset charset)

Decodes an application/x-www-form-urlencoded string using a specific Charset. The supplied charset is used to determine what characters are represented by any consecutive sequences of the form "%xy".

Note: The World Wide Web Consortium Recommendation states that UTF-8 should be used. Not doing so may introduce incompatibilities.

Parameters:

cs - the CharSequence to decode

charset - the given charset

Returns:

the newly decoded String

Throws:

java.lang.NullPointerException - if s or charset is null

java.lang.IllegalArgumentException - if the implementation encounters illegal characters

See Also:

URLEncoder#encode(java.lang.String, java.nio.charset.Charset)

decode

public static java.lang.String decode(java.lang.CharSequence cs,
                                      java.lang.String enc)
                               throws java.io.UnsupportedEncodingException

Decodes an application/x-www-form-urlencoded string using a specific encoding scheme.

This method behaves the same as decode(String s, Charset charset) except that it will look up the charset using the given encoding name.

Parameters:

s - the CharSequence to decode

enc - The name of a supported character encoding.

Returns:

the newly decoded String

Throws:

java.io.UnsupportedEncodingException - If character encoding needs to be consulted, but named character encoding is not supported

Since:

1.4

See Also:

URLEncoder#encode(java.lang.String, java.lang.String)