public abstract class Escaper extends Object
For example, an XML escaper would convert the literal string "Foo<Bar>" into "Foo<Bar>" to prevent "<Bar>" from being confused with an XML tag. When the
resulting XML document is parsed, the parser API will return this text as the original literal
string "Foo<Bar>".
An Escaper instance is required to be stateless, and safe when used concurrently by
multiple threads.
Because, in general, escaping operates on the code points of a string and not on its
individual char values, it is not safe to assume that escape(s) is equivalent to
escape(s.substring(0, n)) + escape(s.substring(n)) for arbitrary n. This is
because of the possibility of splitting a surrogate pair. The only case in which it is safe to
escape strings and concatenate the results is if you can rule out this possibility, either by
splitting an existing long string into short strings adaptively around surrogate pairs, or by starting
with short strings already known to be free of unpaired surrogates.
The two primary implementations of this interface are CharEscaper and UnicodeEscaper. They are heavily optimized for performance and greatly simplify the task of
implementing new escapers. It is strongly recommended that when implementing a new escaper you
extend one of these classes. If you find that you are unable to achieve the desired behavior
using either of these classes, please contact the Java libraries team for advice.
Popular escapers are defined as constants in classes like HtmlEscapers and XmlEscapers. To create
your own escapers, use CharEscaperBuilder, or extend CharEscaper or UnicodeEscaper.
| 限定符 | 构造器和说明 |
|---|---|
protected |
Escaper()
Constructor for use by subclasses.
|
public abstract String escape(String string)
Note that this method may treat input characters differently depending on the specific escaper implementation.
UnicodeEscaper handles UTF-16
correctly, including surrogate character pairs. If the input is badly formed the escaper
should throw IllegalArgumentException.
CharEscaper handles Java characters independently and does not verify the input
for well formed characters. A CharEscaper should not be used in situations where
input is not guaranteed to be restricted to the Basic Multilingual Plane (BMP).
string - the literal string to be escapedstringNullPointerException - if string is nullIllegalArgumentException - if string contains badly formed UTF-16 or cannot be
escaped for any other reasonpublic final Function<String,String> asFunction()
Function that invokes escape(String) on this escaper.Copyright © 2019. All rights reserved.