Class PercentEscaper (1.45.3)

A UnicodeEscaper that escapes some set of Java characters using the URI percent encoding scheme. The set of safe characters (those which remain unescaped) is specified on construction.

For details on escaping URIs for use in web pages, see RFC 3986 - section 2.4 and RFC 3986 - appendix A

When encoding a String, the following rules apply:

• The alphanumeric characters "a" through "z", "A" through "Z" and "0" through "9" remain the same.
• Any additionally specified safe characters remain the same.
• If plusForSpace is true, the space character " " is converted into a plus sign "+".
• All other characters are converted into one or more bytes using UTF-8 encoding. Each byte is then represented by the 3-character string "%XY", where "XY" is the two-digit, uppercase, hexadecimal representation of the byte value.

RFC 3986 defines the set of unreserved characters as "-", "_", "~", and "." It goes on to state:

URIs that differ in the replacement of an unreserved character with its corresponding percent-encoded US-ASCII octet are equivalent: they identify the same resource. However, URI comparison implementations do not always perform normalization prior to comparison (see Section 6). For consistency, percent-encoded octets in the ranges of ALPHA (%41-%5A and %61-%7A), DIGIT (%30-%39), hyphen (%2D), period (%2E), underscore (%5F), or tilde (%7E) should not be created by URI producers and, when found in a URI, should be decoded to their corresponding unreserved characters by URI normalizers.

Note: This escaper produces uppercase hexadecimal sequences. From RFC 3986:
"URI producers and normalizers should use uppercase hexadecimal digits for all percent-encodings."

A string of safe characters that mimics the behavior of java.net.URLEncoder.

A string of characters that do not need to be encoded when used in URI path segments, as specified in RFC 3986. Note that some of these characters do need to be escaped when used in other parts of the URI.

A string of characters that do not need to be encoded when used in URI query strings, as specified in RFC 3986. Note that some of these characters do need to be escaped when used in other parts of the URI.

A string of characters that do not need to be encoded when used in URI user info part, as specified in RFC 3986. Note that some of these characters do need to be escaped when used in other parts of the URI.

A string of characters that do not need to be encoded when used in URI Templates reserved expansion, as specified in RFC 6570. This includes the safe characters plus all reserved characters.

For details on escaping URI Templates using the reserved expansion, see RFC 6570 - section 3.2.3.

Constructs a URI escaper with the specified safe characters. The space character is escaped to %20 in accordance with the URI specification.

Deprecated. use PercentEscaper(String safeChars) instead which is the same as invoking this method with plusForSpace set to false. Escaping spaces as plus signs does not conform to the URI specification.

Constructs a URI escaper that converts all but the specified safe characters into hexadecimal percent escapes. Optionally space characters can be converted into a plus sign + instead of %20. and optional handling of the space

Escapes the given Unicode code point in UTF-8.

Returns the escaped form of a given literal string.

If you are escaping input in arbitrary successive chunks, then it is not generally safe to use this method. If an input string ends with an unmatched high surrogate character, then this method will throw IllegalArgumentException. You should ensure your input is valid UTF-16 before calling this method.

Scans a sub-sequence of characters from a given CharSequence, returning the index of the next character that requires escaping.

Note: When implementing an escaper, it is a good idea to override this method for efficiency. The base class implementation determines successive Unicode code points and invokes #escape(int) for each of them. If the semantics of your escaper are such that code points in the supplementary range are either all escaped or all unescaped, this method can be implemented more efficiently using CharSequence#charAt(int).

Note however that if your escaper does not escape characters in the supplementary range, you should either continue to validate the correctness of any surrogate characters encountered or provide a clear warning to users that your escaper does not validate its input.

See PercentEscaper for an example.