Introduction to JAXP parsing of xml parsing methods

 XML解析	
		1 引入
		xml文件除了给开发者看，更多的情况使用[程序读取xml文件]的内容。这叫做xml解析
		2 XML解析方式（原理不同）
			DOM解析
			SAX解析
		3 XML解析工具
				DOM解析原理:
						1）JAXP （oracle-Sun公司官方）
						2）JDOM工具（非官方）
						3）Dom4J工具（非官方）
							三大框架（默认读取xml的工具就是Dom4j）
						.......

				SAX解析原理：
						1）Sax解析工具（oracle-sun公司官方）

The following introduces the parsing principle of JAXP:

lJAXP: (Java API for XML Processing)The development package is part of JavaSE, which consists of the following packages and their sub-packages:

•org.w3c.dom:Provides a standard interface for parsing XML##DOM

•

org.xml.sax: Provides SAX way to parseXML's standard interface

•

javax.xml:provides parsing XMLDocument class

l

javax.xml.parsersIn the package, several are defined Factory class. We can get the DOM and SAX## that parse the XML document by calling these factory classes. #Parser object. •

DocumentBuilderFactory•

SAXParserFactoryl

javax.xml.parsers#DocumentBuilderFactory in the package is used to create DOMPattern parser object , DocumentBuilderFactory is an abstract factory class, which cannot be instantiated directly, but this class provides a newInstance method, which will According to the parser installed by default on the local platform, a factory object is automatically created and returned. Process:

##

调用 DocumentBuilderFactory.newInstance() 方法得到创建 DOM 解析器的工厂。

调用工厂对象的 newDocumentBuilder方法得到 DOM 解析器对象。

调用 DOM 解析器对象的 parse() 方法解析 XML 文档，得到代表整个文档的 Document 对象，进而可以利用DOM特性对整个XML文档进行操作了。

The specific code to obtain the document object is as follows:

//1. 获得工厂 
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		
		// 2. 拿到 builder 对象
		DocumentBuilder builder = factory.newDocumentBuilder();
		
		//3. 拿到 代表book.xml文件的document 对象 
		// ctrl+1 --- 提示 快速  分配一个变量值 
		Document document = builder.parse("src/book.xml");

##The next article will include an interlude - unit Test the framework, and then introduce some CRUD examples to have an intuitive understanding of JAXP parsing xml.

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