VTD-XML -- XPath Evaluation Performance

Question

Konstantinos Sofos 2014-7-3

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/140075-vtd-xml-xpath-evaluation-performance

回答： Koen 2014-11-14

For a lot of years i use DOM oblects (JDK) to read XML files (XPath). Since some weeks i found the * VTD-XML * and i would like to ask if anyone has arleady use it, if yes how and what is your opinion. Thanks in advance.

classdef XPath 
  % xpath.XPath Class for using xpath on Java DOM objects
  %
  %    This class is a small wrapper for the XPATH functionality packaged
  %    in javax.xml.parsers.* and javax.xml.xpath.*
  %    
  properties
     domFactory
     builder
     doc
     factory
     xpath
  end
    methods
        function this = XPath( xmlFile )
            % XPath Constructor
            %
            %    The constructor only takes one argument, an xml file.
            %    It returns a handle to the object created.
            import javax.xml.parsers.*;
            import javax.xml.xpath.*;
            this.domFactory = DocumentBuilderFactory.newInstance();
            this.builder = this.domFactory.newDocumentBuilder();
            this.doc = this.builder.parse(xmlFile);
            this.factory = XPathFactory.newInstance();
            this.xpath = this.factory.newXPath();
        end
        function result = evaluateExpression( this, expressionStr )
            % evaluateExpression Evaluate XPATH expression on doc object
            %
            %    This is the general function, which will perform an xpath
            %    search on the top level object.
            %
            %    See also xpath.XPath/setBaseDoc
            import javax.xml.xpath.*;
            expression = this.xpath.compile(expressionStr);
            result = expression.evaluate(this.doc, XPathConstants.NODESET);
        end
        function result = evaluateExpressionInElem( this, expressionStr, elem )
            import javax.xml.xpath.*;
            expression = this.xpath.compile(expressionStr);
            result = expression.evaluate(elem, XPathConstants.NODESET);
        end
        function newDoc = setBaseDoc( this, expressionStr )
            % setBaseDoc Change what the doc attribute points to
           elem = evaluateExpression( this, expressionStr );
           if ~isempty( elem ) && elem.getLength==1
               this.doc = elem.item(0);
           end
           if nargout > 0
               newDoc = this.doc;
           end
        end
    end
 end