@DoNotMock("Use Escapers.nullEscaper() or another methods from the *Escapers classes") @GwtCompatible public abstract class Escaper extends java.lang.ObjectAn object that converts literal text into a format safe for inclusion in a particular context (such as an XML document). Typically (but not always), the inverse process of "unescaping" the text is performed automatically by the relevant parser.
For example, an XML escaper would convert the literal string
"<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
Escaperinstance 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
charvalues, 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
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.
- David Beaumont
Constructors Modifier Constructor Description
Escaper()Constructor for use by subclasses.
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description
escape(java.lang.String string)Returns the escaped form of a given literal string.
protected Escaper()Constructor for use by subclasses.
public abstract java.lang.String escape(java.lang.String string)Returns the escaped form of a given literal string.
Note that this method may treat input characters differently depending on the specific escaper implementation.
UnicodeEscaperhandles UTF-16 correctly, including surrogate character pairs. If the input is badly formed the escaper should throw
CharEscaperhandles Java characters independently and does not verify the input for well formed characters. A
CharEscapershould 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 escaped
- the escaped form of
stringcontains badly formed UTF-16 or cannot be escaped for any other reason