matlab.io.xml.dom.EntityResolver Class
Namespace: matlab.io.xml.dom
Description
matlab.io.xml.dom.EntityResolver
is an abstract base class for deriving
entity resolvers that resolve entity references encountered by a parser while parsing an XML
file or string.
The matlab.io.xml.dom.EntityResolver
class is a handle
class.
Class Attributes
Abstract | true |
ConstructOnLoad | true |
HandleCompatible | true |
For information on class attributes, see Class Attributes.
Methods
Public Methods
resolveEntity |
The |
Examples
Resolve an XML Entity
This example creates an entity resolver, configures a parser to use the resolver, and parses an XML file that includes an entity reference.
If the path of a file that contains an entity is specified relative to the location of the main XML document, a parser can use a default entity resolver to resolve the path. In this case, you do not have to define your own resolver. To make sure that a resolver is required for this example, the example saves the file that contains the entity and the main XML file in different folders at the same level.
In a subfolder chapters
of the current folder, create a file
chapter.xml
that contains this markup for a chapter:
<?xml version="1.0" encoding="UTF-8"?> <chapter><title color="red">Introduction</title></chapter>
In a subfolder books
that is at the same level as the
chapters
folder, create a file books.xml
that
contains this markup for a book:
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE book [ <!ENTITY chapter SYSTEM "chapters/chapter.xml"> ]> <book> &chapter; </book>
book.xml
contains the entity reference
&chapter;
and declares that the resource for the entity is
chapters/chapter.xml
.
Define a subclass of the abstract class
matlab.io.xml.dom.EntityResolver
and name it
BookEntityResolver
. Save BookEntityResolver.m
in
the folder that contains the chapters
and books
folder.
classdef BookEntityResolver < matlab.io.xml.dom.EntityResolver properties BaseDir end methods function obj = BookEntityResolver(baseDir) obj@matlab.io.xml.dom.EntityResolver() obj.BaseDir = baseDir; end function res = resolveEntity(obj,ri) import matlab.io.xml.dom.ResourceIdentifierType if getResourceIdentifierType(ri) == ResourceIdentifierType.ExternalEntity res = fullfile(obj.BaseDir, ri.SystemID); end end end end
Create an entity resolver as an instance of the
BookEntityResolver
class.
import matlab.io.xml.dom.*
resolver = BookEntityResolver(pwd);
Create a parser and configure it to use the resolver.
p = Parser(); p.Configuration.EntityResolver = resolver; p.Configuration.AllowDoctype = true;
Parse the file book.xml
into a
matlab.io.xml.dom.Document
object.
filePath = "books/book.xml";
domDoc = parseFile(p,filePath);
To see that the chapter
entity was resolved, find the
chapter
element node in the document.
nl = getElementsByTagName(domDoc,"chapter");
ch = node(nl,1)
ch = Element with properties: TagName: 'chapter' HasAttributes: 0 TextContent: 'Introduction' Children: [1×1 matlab.io.xml.dom.Element]
Version History
Introduced in R2021a
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