Java 解析XML

解析xml方式

Java解析xml常用方式DOM4j

DOM4j解析

package com.cxx.xml;
import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

import java.io.File;
import java.util.Iterator;
import java.util.List;

/**
 * @Author: cxx
 * Dom4j解析xml
 * @Date: 2018/5/30 12:21
 */
public class Dom4JDemo {
    public static void main(String[] args) throws Exception {
        //1.创建Reader对象
        SAXReader reader = new SAXReader();
        //2.加载xml
        Document document = reader.read(new File("src/main/resources/demo.xml"));
        //3.获取根节点
        Element rootElement = document.getRootElement();
        Iterator iterator = rootElement.elementIterator();
        while (iterator.hasNext()){
            Element stu = (Element) iterator.next();
            List<Attribute> attributes = stu.attributes();
            System.out.println("======获取属性值======");
            for (Attribute attribute : attributes) {
                System.out.println(attribute.getValue());
            }
            System.out.println("======遍历子节点======");
            Iterator iterator1 = stu.elementIterator();
            while (iterator1.hasNext()){
                Element stuChild = (Element) iterator1.next();
                System.out.println("节点名："+stuChild.getName()+"---节点值："+stuChild.getStringValue());
            }
        }
    }
}

XPath

概述

XPath 是一门在 XML 文档中查找信息的语言， 可用来在 XML 文档中对元素和属性进行遍历。XPath 是 W3C XSLT 标准的主要元素，并且 XQuery 和 XPointer 同时被构建于 XPath 表达之上。因此，对 XPath 的理解是很多高级 XML 应用的基础
XPath非常类似对数据库操作的SQL语言，或者说JQuery，它可以方便开发者抓起文档中需要的东西(dom4j也支持xpath)

案例:

import java.io.IOException;
import java.io.InputStream;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
public class TestXPath {
  public static void main(String[] args) {
    read();
  }
  public static void read() {
    try {
      DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
      DocumentBuilder builder = dbf.newDocumentBuilder();
      InputStream in = TestXPath.class.getClassLoader().getResourceAsStream("test.xml");
      Document doc = builder.parse(in);
      XPathFactory factory = XPathFactory.newInstance();
      XPath xpath = factory.newXPath();
      // 选取所有class元素的name属性
      // XPath语法介绍： http://w3school.com.cn/xpath/
      XPathExpression expr = xpath.compile("//class/@name");
      NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
      for (int i = 0; i < nodes.length();i++){
        System.out.println("name = " + nodes.item(i).getNodeValue());
      }
    } catch (XPathExpressionException e) {
      e.printStackTrace();
    } catch (ParserConfigurationException e) {
      e.printStackTrace();
    } catch (SAXException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}