Dom4j使用入门
1. 导包
目前使用的是第三方工具,不是原生的JDK
导入第三方Jar包
2. 设置IDEA
3. Dom4j涉及到的方法
SAXReader();
解析XML文件使用的核心类
read() --> XML文件Document对象
Document document = new SAXReader().read(new File("./xml/User.xml"));
Document对象中可以使用方法
Element getRootElement();
获取当前XML文件的根节点对象
Element对象中可以使用方法
List elements();
当前节点下的所有子节点
List elements(String name);
当前节点下所有指定名字的子节点
Element element();
获取当前节点下的第一个子节点
Element element(String name);
获取当前节点下指定名字的第一个子节点
Attribute getAttribute(String name);
根据属性名获取对应的属性对象Attribute
Attribute节点中可以使用String getValue()来获取对应的节点数据
String getName();
获取当前节点的名字
String getText();
获取当前节点对应的文本数据
package com.qfedu.d_xmlparse;
import jdk.nashorn.internal.ir.CallNode;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import java.io.File;
import java.util.List;
public class Demo1 {
public static void main(String[] args) throws DocumentException {
Document document = new SAXReader().read(new File("./xml/User.xml"));
Element rootElement = document.getRootElement();
List<Element> elements = rootElement.elements();
Element teacher = rootElement.element("teacher");
System.out.println(teacher.attribute("id").getValue());
List<Element> elements1 = teacher.elements();
for (Element element : elements1) {
System.out.println(element.getName() + ":" + element.getText());
}
}
}
Dom4j Xpath解析读取XML文件
package com.qfedu.d_xmlparse;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
import java.io.File;
import java.util.List;
public class Demo2 {
public static void main(String[] args) throws DocumentException {
Document document = new SAXReader().read(new File("./xml/User.xml"));
Element rootElement = document.getRootElement();
List list = rootElement.selectNodes("//user");
for (Object o : list) {
Element element = (Element) o;
int id = Integer.parseInt(element.attributeValue("id"));
String name = element.element("name").getText();
int age = Integer.parseInt(element.element("age").getText());
String gender = element.element("gender").getText();
System.out.println("User[id=" + id + ", name=" + name
+ ", age=" + age + ", gender=" + gender + "]");
}
System.out.println("--------------------------------------");
System.out.println();
Node node = rootElement.selectSingleNode("//user[1]");
System.out.println(node);
System.out.println("--------------------------------------");
System.out.println();
Node node1 = rootElement.selectSingleNode("//user[@id=9]");
System.out.println(node1);
System.out.println("--------------------------------------");
System.out.println();
List list1 = rootElement.selectNodes("//user[gender='male']");
for (Object o : list1) {
System.out.println(o);
}
System.out.println("--------------------------------------");
System.out.println();
List list2 = rootElement.selectNodes("//user[age<20]");
for (Object o : list2) {
System.out.println(o);
}
}
}
package com.qfedu.d_xmlparse;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
import java.io.File;
import java.util.List;
public class Demo3 {
public static void main(String[] args) throws DocumentException {
Document document = new SAXReader().read(new File("./xml/User.xml"));
Element rootElement = document.getRootElement();
System.out.println("--------------------------------------");
System.out.println();
Node node = rootElement.selectSingleNode("//user[last()]");
System.out.println(node);
System.out.println("--------------------------------------");
System.out.println();
List list = rootElement.selectNodes("//user[position() < 3]");
for (Object o : list) {
System.out.println(o);
}
System.out.println("--------------------------------------");
System.out.println();
List list1 = rootElement.selectNodes("//name | // age");
for (Object o : list1) {
Element element = (Element) o;
System.out.println(element.getText());
}
}
}
XML文件保存
流程:
1. 创建Document对象
2. 通过Document对象来添加元素
addElment();
addAttribute();
package com.qfedu.e_xmlwrite;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import java.io.FileWriter;
import java.io.IOException;
public class Demo1 {
public static void main(String[] args) throws IOException {
Document document = DocumentHelper.createDocument();
Element root = document.addElement("students");
Element element = root.addElement("student").addAttribute("id", "qf1");
element.addElement("name").addText("骚磊");
element.addElement("age").addText("16");
element.addElement("sex").addText("male");
FileWriter fileWriter = new FileWriter("./xml/student.xml");
document.write(fileWriter);
fileWriter.close();
}
}