tinyXML100120：tinyXML备忘

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tinyXML是一个小巧实用的xml解析工具，简简单单的，由两个头文件和四个cpp文件组成，直接用在自己的代码中或者生成库使用都很方便。tinyXML是采用top-down的方式解析xml，简洁明了。当然tinyXML的个头也决定了它的功能有限，例如不支持DTD&XSL，但应付简单场景也就足够了。

 

按照DOM的思想，xml被看成各个节点(元素)的嵌套和排列，TiXmlNode是节点基类，由此派生出TiXmlDocument，代表整个xml文档；TiXmlComment，TiXmlDeclaration，TiXmlElement，TiXmlText，和TiXmlUnknow是各种节点的类。

              TiXmlNode

                     TiXmlComment

                     TiXmlDeclaration

                     TiXmlDocument

                     TiXmlElement

                     TiXmlText

                     TiXmlUnknow

节点的属性(attribute)则用TiXmlAttribute来表示。

特别一提的是TiXmlHandle类，它的引入是专门为了解决累赘的空指针检查问题的。下面粘贴的是tinyXML文档中的一段解释。

A TiXmlHandle is a class that wraps a node pointer with null checks; this is an incredibly useful thing.

Note that TiXmlHandle is not part of the TinyXml DOM structure. It is a separate utility class.

Take an example:

       

              

                      

                      

              

       

       

Assuming you want the value of "attributeB" in the 2nd "Child" element, it's very easy to write a *lot* of code that looks like:

        TiXmlElement* root = document.FirstChildElement( "Document" );

        if ( root )

        {

               TiXmlElement* element = root->FirstChildElement( "Element" );

               if ( element )

               {

                       TiXmlElement* child = element->FirstChildElement( "Child" );

                       if ( child )

                       {

                               TiXmlElement* child2 = child->NextSiblingElement( "Child" );

                               if ( child2 )

                               {

                                      // Finally do something useful.

       

And that doesn't even cover "else" cases. TiXmlHandle addresses the verbosity of such code. A TiXmlHandle checks for null pointers so it is perfectly safe and correct to use:

        TiXmlHandle docHandle( &document );

        TiXmlElement* child2 = docHandle.FirstChild( "Document" ).FirstChild( "Element" ).Child( "Child", 1 ).ToElement();

        if ( child2 )

        {

               // do something useful

       

Which is MUCH more concise and useful.