Java novice learning guide [day24] ---xml parsing

1、xml

XML (eXtensible Markup Language), is an extensible markup language

grammar:

a. The document statement must be on the first line (development environment: project environment, system environment; encoding character set in the current file)

b. There is one and only one root label, with a beginning and an end

c. Can not be nested between tags

d. CDATA area<![CDATA[Data with special characters]]>

e. Strictly case sensitive

effect:

a. Used to make configuration files

b. The format used for data exchange

2. DOM model

DOM: Document Object Model (convert every node in a document into a Java corresponding object)

D	Document	Document (XML document): xml file on the disk
THE	Object	Object (Java object): encapsulate the xml file into a Java object
M	Model	model

Some of these types describe xml documents

Node, Element, Attribute-Attr, Text

3. xml parsing

Tool: third-party tool dom4j

//使用
①：导包
②：创建Document对象
			new SAXReader().read(File file) 
③：获取根标签
			Element getRootElement();
④：获取根下面标签元素
			获取单个：Element element(String tagName);
			获取多个：List elements(String tagName);
常用方法：
			创建一个 标签： addElement(String tagName)
			获取标签文本： Text getText();
			设置文本： void setText(String value);
			移除标签： void remove(Element e);
			获取父节点元素：Element getParent();
//将对象里面的数据同步到xlm			
		XMLWriter writer = new XMLWriter(new FileWriter(file));
		writer.write(document);
		writer.close();