tutorial0.html - Android社区 - https://www.androidos.net.cn/

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head><meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1">
<title>TinyXml: TinyXML Tutorial</title>
<link href="doxygen.css" rel="stylesheet" type="text/css">
</head><body>
<!-- Generated by Doxygen 1.4.4 -->
<div class="qindex"><a class="qindex" href="index.html">Main&nbsp;Page</a> | <a class="qindex" href="hierarchy.html">Class&nbsp;Hierarchy</a> | <a class="qindex" href="annotated.html">Class&nbsp;List</a> | <a class="qindex" href="files.html">File&nbsp;List</a> | <a class="qindex" href="functions.html">Class&nbsp;Members</a></div>
<div class="nav">
<a class="el" href="index.html">index</a></div>
<h1><a class="anchor" name="tutorial0">TinyXML Tutorial</a></h1><h1>Tutorial Preliminary </h1>
<p>
These pages contains a bunch of examples of using TinyXml.<p>
Each demo is written in a standalone function. If you want to try the code, all you need to do is copy/paste the code into a file, then have a main to call it.<p>
So if the example has a function:<p>
<div class="fragment"><pre class="fragment">	void write_simple_doc()
	{
		...
	}
	</pre></div><p>
then the *complete* program you need to try it is:<p>
<div class="fragment"><pre class="fragment">	#include "stdafx.h" // &lt;-- you MIGHT need this
	#include "tinyxml.h" // &lt;-- you definitely need this ;)

	void write_simple_doc()
	{
		...
	}

	void main( void )
	{
		write_simple_doc();
	}
	</pre></div><p>
Two example XML datasets/files will be used. The first looks like this:<p>
<div class="fragment"><pre class="fragment">	&lt;?xml version="1.0" ?&gt;
	&lt;Hello&gt;World&lt;/Hello&gt;
	</pre></div><p>
The other:<p>
<div class="fragment"><pre class="fragment">	&lt;?xml version="1.0" ?&gt;
	&lt;poetry&gt;
		&lt;verse&gt;
			Alas
			  Great Whatever
				Alas (again)
		&lt;/verse&gt;
	&lt;/poetry&gt;
	</pre></div><p>
<h1>Getting Started </h1>
<p>
<h2>Load XML from a file </h2>
<p>
Loading a file is as simple as:<p>
<div class="fragment"><pre class="fragment">	void load_file( )
	{
		TiXmlDocument doc( "demo.xml" );
		bool loadOkay = doc.LoadFile();

		if ( loadOkay )
		{
			// Your document is loaded - do what you like
			// with it.
			//
			// Here we'll dump the structure to STDOUT,
			// just for example
			dump_to_stdout( &amp;doc );
		}
		else
		{
			// load failed
		}
	}
	</pre></div><p>
The ``dump_to_stdout`` function is defined in the section `Dump structure of a Document to STDOUT` below. If you run this program with this XML:<p>
<div class="fragment"><pre class="fragment">	&lt;?xml version="1.0" ?&gt;
	&lt;Hello&gt;World&lt;/Hello&gt;
	</pre></div><p>
You'll see this:<p>
<div class="fragment"><pre class="fragment">	DOCUMENT
	+ DECLARATION
	+ ELEMENT Hello
	  + TEXT[World]
	</pre></div><p>
<h2>Building Documents Programatically </h2>
<p>
Example:<p>
<div class="fragment"><pre class="fragment">	void write_simple_doc( )
	{
		// Make xml: &lt;?xml ..&gt;&lt;Hello&gt;World&lt;/Hello&gt;
		TiXmlDocument doc;
		TiXmlDeclaration * decl = new TiXmlDeclaration( "1.0", "", "" );
		TiXmlElement * element = new TiXmlElement( "Hello" );
		TiXmlText * text = new TiXmlText( "World" );
		element-&gt;LinkEndChild( text );
		doc.LinkEndChild( decl );
		doc.LinkEndChild( element );
		
		dump_to_stdout( &amp;doc );
		doc.SaveFile( "madeByHand.xml" );
	}
	</pre></div><p>
Alternatively:<p>
<div class="fragment"><pre class="fragment">	void write_simple_doc2( )
	{
		// same as write_simple_doc1 but add each node
		// as early as possible into the tree.
	
		TiXmlDocument doc;
		TiXmlDeclaration * decl = new TiXmlDeclaration( "1.0", "", "" );
		doc.LinkEndChild( decl );
		
		TiXmlElement * element = new TiXmlElement( "Hello" );
		doc.LinkEndChild( element );
		
		TiXmlText * text = new TiXmlText( "World" );
		element-&gt;LinkEndChild( text );
		
		dump_to_stdout( &amp;doc );
		doc.SaveFile( "madeByHand2.xml" );
	}
	</pre></div><p>
Both of these produce the same XML, namely:<p>
<div class="fragment"><pre class="fragment">	&lt;?xml version="1.0" ?&gt;
	&lt;Hello&gt;World&lt;/Hello&gt;
	</pre></div><p>
Or in structure form:<p>
<div class="fragment"><pre class="fragment">	DOCUMENT
	+ DECLARATION
	+ ELEMENT Hello
	  + TEXT[World]
	</pre></div><p>
<h2>Saving Documents to File </h2>
<p>
This function:<p>
<div class="fragment"><pre class="fragment">	void write_simple_doc3( )  
	{  
		// This example courtesy of polocolege
	 
		TiXmlDocument doc;  
		TiXmlDeclaration * decl = new TiXmlDeclaration( "1.0", "", "" );  
		doc.LinkEndChild( decl );  
	 
		TiXmlElement * element = new TiXmlElement( "Hello" );  
		doc.LinkEndChild( element );  
	 
		TiXmlText * text = new TiXmlText( "Opening a new salutation" );  
		element-&gt;LinkEndChild( text );  
	 
		TiXmlElement * element2 = new TiXmlElement( "Greeting" );  
		element-&gt;LinkEndChild( element2 );  
	 
		TiXmlText * text2 = new TiXmlText( "How are you?" );  
		element2-&gt;LinkEndChild( text2 );  
	 
		TiXmlElement * element3 = new TiXmlElement( "Language" );  
		element2-&gt;LinkEndChild( element3 );  
	 
		TiXmlText * text3 = new TiXmlText( "English" );  
		element3-&gt;LinkEndChild( text3 );  
	 
		TiXmlElement * element4 = new TiXmlElement( "Exclamation" );  
		element-&gt;LinkEndChild( element4 );  
	 
		TiXmlText * text4 = new TiXmlText( "You have children!" );  
		element4-&gt;LinkEndChild( text4 );  
	 
		dump_to_stdout( &amp;doc );
		doc.SaveFile( "madeByHand3.xml" );  
	}  
	</pre></div><p>
Produces this structure:<p>
<div class="fragment"><pre class="fragment">	Document
	+ Declaration
	+ Element "Hello"
	  + Text: [Opening a new salutation]
	  + Element "Greeting"
		+ Text: [How are you?]
		+ Element "Language"
		  + Text: [English]
	  + Element "Exclamation"
		+ Text: [You have children!]
	</pre></div><p>
The file ``madeByHand3.xml`` looks exactly like this (including indents):<p>
<div class="fragment"><pre class="fragment">	&lt;?xml version="1.0" ?&gt;
	&lt;Hello&gt;Opening a new salutation
	    &lt;Greeting&gt;How are you?
	        &lt;Language&gt;English&lt;/Language&gt;
	    &lt;/Greeting&gt;
	    &lt;Exclamation&gt;You have children!&lt;/Exclamation&gt;
	&lt;/Hello&gt;
	</pre></div><p>
I was surprised that TinyXml, by default, writes the XML in what other APIs call a "pretty" format - it modifies the whitespace of text of elements that contain other nodes so that writing the tree includes an indication of nesting level.<p>
I haven't looked yet to see if there is a way to turn off indenting when writing a file - its bound to be easy.<p>
[Lee: It's easy in STL mode, just use cout &lt;&lt; myDoc. Non-STL mode is always in "pretty" format. Adding a switch would be a nice feature and has been requested.]<p>
<h1>Iterating Over Documents </h1>
<p>
<h2>Dump structure of a Document to STDOUT </h2>
<p>
Often when you're starting its helpful and reassuring to know that you're document got loaded as you expect it to.<p>
Below I've defined a function to walk a document and write contents to STDOUT:<p>
<div class="fragment"><pre class="fragment">	// a utility function defining a very simple method to indent a line of text
	const char * getIndent( unsigned int numIndents )
	{
		static const char * pINDENT = "                                      + ";
		static const unsigned int LENGTH = strlen( pINDENT );
	
		if ( numIndents &gt; LENGTH ) numIndents = LENGTH;
	
		return &amp;pINDENT[ LENGTH-numIndents ];
	}
	
	void dump_to_stdout( TiXmlNode * pParent, unsigned int indent = 0 )
	{
		if ( !pParent ) return;
	
		TiXmlText *pText;
		int t = pParent-&gt;Type();
		printf( "%s", getIndent( indent));
	
		switch ( t )
		{
		case TiXmlNode::DOCUMENT:
			printf( "Document" );
			break;
	
		case TiXmlNode::ELEMENT:
			printf( "Element \"%s\"", pParent-&gt;Value() );
			break;
	
		case TiXmlNode::COMMENT:
			printf( "Comment: \"%s\"", pParent-&gt;Value());
			break;
	
		case TiXmlNode::UNKNOWN:
			printf( "Unknown" );
			break;
	
		case TiXmlNode::TEXT:
			pText = pParent-&gt;ToText();
			printf( "Text: [%s]", pText-&gt;Value() );
			break;
	
		case TiXmlNode::DECLARATION:
			printf( "Declaration" );
			break;
		default:
			break;
		}
		printf( "\n" );
	
		TiXmlNode * pChild;
	
		for ( pChild = pParent-&gt;FirstChild(); pChild != 0; pChild = pChild-&gt;NextSibling()) 
		{
			dump_to_stdout( pChild, indent+2 );
		}
	}
	</pre></div><p>
To load a file and dump its structure:<p>
<div class="fragment"><pre class="fragment">	void load_and_display( )
	{
		// important for the poetry demo, but you may not need this 
		// in your own projects
		TiXmlBase::SetCondenseWhiteSpace( false );
	
		TiXmlDocument doc( "demo.xml" );
		bool loadOkay = doc.LoadFile();
	
		if ( loadOkay )
		{
			dump_to_stdout( &amp;doc );
		}
		else
		{
			printf( "Something went wrong\n" );
		}
	}
	</pre></div><p>
If you run this with the first XML file you'll see this on STDOUT:<p>
<div class="fragment"><pre class="fragment">	DOCUMENT
	+ DECLARATION
	+ ELEMENT Hello
	  + TEXT[World]
	</pre></div><p>
and on the second XML file:<p>
<div class="fragment"><pre class="fragment">	DOCUMENT
	+ DECLARATION
	+ ELEMENT poetry
	  + COMMENT:  my great work of art
	  + ELEMENT verse
	    + TEXT[
	Alas
	  Great Whatever
	    Alas (again)
	]
	</pre></div><p>
Note that if you call dump_to_stdout like this:<p>
<div class="fragment"><pre class="fragment">	dump_to_stdout( doc.RootElement());
	</pre></div><p>
You'll see this instead:<p>
<div class="fragment"><pre class="fragment">	ELEMENT Hello
	+ TEXT[World]
	</pre></div><p>
and:<p>
<div class="fragment"><pre class="fragment">	ELEMENT poetry
	+ COMMENT:  my great work of art
	+ ELEMENT verse
  	+ TEXT[
	Alas
	  Great Whatever
	    Alas (again)
	] 
	</pre></div><p>
<em> Authors and Changes <ul>
<li>
Written by Ellers, April 2005  </li>
<li>
Minor edits and integration into doc system, Lee Thomason September 2005  </li>
</ul>
</em> <hr size="1"><address style="align: right;"><small>Generated on Sat Oct 8 14:15:30 2005 for TinyXml by&nbsp;
<a href="http://www.doxygen.org/index.html">
<img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.4.4 </small></address>
</body>
</html>