Parsing of XML files

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Catalog

Knowledge required

1、Java Three configuration locations and reading methods of configuration files in

2、dome4j Common methods

3、xpath grammar

analysis XML Code operation

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Knowledge required

1、Java Three configuration locations and reading methods of configuration files in

Class name .class.getResourceAsStream("xxx")： Get the documents under the same package

Class name .class.getResourceAsStream("/xxx")： Get the file under the root directory

context.getResourceAsStream("/WIN-INF/xxx")： Get WIN-INF Safe path

2、dome4j Common methods

selectNodes： Get multiple elements

selectSingleNode： Get a single element

getRootElement()： Get the root element

attributeValue： Only elements can click this method to get values

getText： Get the element text

notes ： Elements can be nodes , But the attribute in the element is a node, not an element

3、xpath grammar

/： Positioning path

@： attribute

analysis XML Code operation

1、 It needs to be parsed XML Case study （config.xml file ）

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE config[
	<!ELEMENT config (action*)>
	<!ELEMENT action (forward*)>
	<!ELEMENT forward EMPTY>
	<!ATTLIST action
	  path CDATA #REQUIRED
	  type CDATA #REQUIRED
	>
	<!ATTLIST forward
	  name CDATA #REQUIRED
	  path CDATA #REQUIRED
	  redirect (true|false) "false"
	>
]>
<config>
	<action path="/studentAction" type="org.lisen.mvc.action.StudentAction">
		<forward name="students" path="/students/studentList.jsp" redirect="false"/>
	</action>
	<action path="/studentAction02" type="org.lisen.mvc.action.StudentAction">
		<forward name="students02" path="/students/studentList.jsp" redirect="false"/>
	</action>
</config>

2、 Before writing parsing code, you need to import jar package

3、 Write the code of parsing operation

public class XmlReader {
	
	public static void main(String[] args) throws Exception {
		InputStream in = XmlReader.class.getResourceAsStream("/config.xml");
		SAXReader reader = new SAXReader();
		Document doc = reader.read(in);

		Element rootElement = doc.getRootElement();
		List<Element> actions = rootElement.selectNodes("action");
		
		for(Element e:  actions) {
			String path = e.attributeValue("path");
			String type = e.attributeValue("type");
			
			System.out.println("action path = "+path);
			System.out.println("action type = "+type);
			
			List<Element> forwards = e.selectNodes("forward");
			for(Element f:  forwards) {
				String name = f.attributeValue("name");
				String fPath = f.attributeValue("path");
				String redirect = f.attributeValue("redirect");
				
				System.out.println("forward name = "+name);
				System.out.println("forward fPath = "+fPath);
				System.out.println("forward redirect = "+redirect);
			}
			System.out.println(" Parsing ended ");
		}
	}
}

Output results （ You can see that you have obtained the information provided above XML Relevant elements and nodes in the file ）