Java Web基础之XML入门

<hr>
	<employee no="3309">
		<name>张三</name>
		<age>31</age>
		<salary>4000</salary>
		<department>
			<dname>会计部</dname>
			<address>xx大厦-B103</address>
		</department>
	</employee>
	<employee no="3310">
		<name>李四</name>
		<age>23</age>
		<salary>34000</salary>
		<department>
			<dname>工程部</dname>
			<address>xx大厦-B103</address>
		</department>
	</employee>
</hr>

<!DOCTYPE hr SYSTEM "hr.dtd">

<?xml version="1.0" encoding="UTF-8"?>
<!ELEMENT hr (employee+)>
<!ELEMENT employee (name,age,salary,department)>
<!ATTLIST employee no CDATA "">
<!ELEMENT name (#PCDATA)>
<!ELEMENT age (#PCDATA)>
<!ELEMENT salary (#PCDATA)>
<!ELEMENT department (dname,address)>
<!ELEMENT dname (#PCDATA)>
<!ELEMENT address (#PCDATA)>
记住加空格，否则失效

<hr xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="hr.xsd">

<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema">
	<element name="hr">
		<!-- complexType标签含义是复杂节点，包含子节点时必须使用这个标签 -->
		<complexType>
			<sequence>
				<element name="employee" minOccurs="1" maxOccurs="999">
					<complexType>
						<sequence>
							<element name="name" type="string"></element>
							<element name="age">
								<simpleType>
									<restriction base="integer">
										<minInclusive value="18"></minInclusive>
										<maxInclusive value="60"></maxInclusive>
									</restriction>
								</simpleType>
							</element>
							<element name="salary" type="integer"></element>
							<element name="department">
								<complexType>
									<sequence>
										<element name="dname" type="string"></element>
										<element name="address" type="string"></element>
									</sequence>
								</complexType>
							</element>
						</sequence>
						<attribute name="no" type="string" use="required"></attribute>
					</complexType>
				</element>
			</sequence>
		</complexType>
	</element>
</schema>

Dom4j遍历XML

记得导入jar包

package com.imooc.dom4j;

import java.awt.List;

import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class HrReader {
	public void readXml() {
		String file="d:/eclipse/xml/src/hr.xml";
		//SAXReader类是读取XML文件的核心类，用于将XML解析后以树的形式保存在内存中
		SAXReader reader=new SAXReader();
		try {
			Document document=reader.read(file);
			//获取XML文档的根节点，即hr标签
			Element root=document.getRootElement();
			//elements方法用于获取指定的标签集合
			java.util.List<Element> employees = root.elements("employee");
			for(Element employee:employees) {
				//element方法用于获取唯一的子节点对象
				Element name=employee.element("name");
				//getText()方法用于获取标签文本
				String empName=name.getText();
				System.out.println(empName);
				System.out.println(employee.elementText("age"));
				System.out.println(employee.elementText("salary"));
				Element department=employee.element("department");
				System.out.println(department.element("dname").getText());
				System.out.println(department.element("address").getText());
				Attribute att=employee.attribute("no");
				System.out.println(att.getText());
			}
		} catch (DocumentException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public static void main(String[] args) {
		HrReader reader=new HrReader();
		reader.readXml();
	}
}

Dom4j更新XML（插入数据）

package com.imooc.dom4j;

import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class HrWriter {
	public void writerXml() {
		String file="d:/eclipse/xml/src/hr.xml";
		SAXReader reader=new SAXReader();
		try {
			Document document=reader.read(file);
			Element root=document.getRootElement();
			Element employee=root.addElement("employee");
			employee.addAttribute("no", "3331");
			Element name =employee.addElement("name");
			name.setText("李铁柱");
			employee.addElement("age").setText("34");
			employee.addElement("salary").setText("3600");
			Element department=employee.addElement("department");
			department.addElement("dname").setText("人事部");
			department.addElement("address").setText("XX大厦-B105");
			Writer writer=new OutputStreamWriter(new FileOutputStream(file),"UTF-8");
			document.write(writer);
			writer.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public static void main(String[] args) {
		HrWriter hrWriter=new HrWriter();
		hrWriter.writerXml();
	}
}

XPath表达式

package com.imooc.dom4j;

import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;

public class XPathTest {
	public void xpath(String xpathExp){
		String file="d:/eclipse/xml/src/hr.xml";
		SAXReader reader=new SAXReader();
		try {
			Document document=reader.read(file);
			//核心
			List<Node> nodes=document.selectNodes(xpathExp);
			for(Node node : nodes){
				//node是Element和属性的父类，需要强制转换
				Element emp=(Element)node;
				System.out.println(emp.attributeValue("no"));
				System.out.println(emp.elementText("name"));
				System.out.println(emp.elementText("age"));
				System.out.println(emp.elementText("salary"));
				System.out.println("=========================");
				
			}
		} catch (DocumentException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public static void main(String[] args) {
		XPathTest testor=new XPathTest();
		//testor.xpath("/hr/employee");
		//testor.xpath("//employee");
		//testor.xpath("//employee[salary<4000]");
		//testor.xpath("//employee[name='李铁柱']");
		//testor.xpath("//employee[@no=3309]");
		//第一位出现的employee节点
		//testor.xpath("//employee[1]");
		//testor.xpath("//employee[last()]");
		//testor.xpath("//employee[position()<3]");
		testor.xpath("//employee[2]|//employee[1]");
	}
}