XML之DOM解析文档 Day24

TestDom.java

package com.sxt.dom;

import java.io.File;
import java.io.IOException;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

/*
 * DOM解析文档：DOM把XML文档映射成一个倒挂的树，每个节点都是一个对象
 * DOM:document object model  文档对象模型
 * 缺点：1.前三步不能省略
 *         2.空白节点没有过滤
 */
public class TestDom {
    public static void main(String[] args) throws Exception {
        //创建解析工厂       DocumentBuilderFactory
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        //创建解析器
        DocumentBuilder builder = factory.newDocumentBuilder();
        //解析文档 获取文档内容
        Document document = builder.parse(new File("product2.xml"));
        //拿到dom树 属性  元素
        NodeList nodeList = document.getElementsByTagName("product");
        //拿到根节点
        Node node = nodeList.item(0);//Node  getNodeType为1
        System.out.println(node.getNodeName());
        //拿到所有子节点
        NodeList childNodes = node.getChildNodes();
        //System.out.println(childNodes.getLength());//5 包括空白  空白也是子节点
        //遍历子节点 包括空格
        for(int i=0; i<childNodes.getLength(); i++){
            Node childNode = childNodes.item(i);
            //System.out.println(childNode.getNodeType());//3表示空白
            //如果节点不是空白    空白：TEXT_NODE
            if(childNode.getNodeType() == Node.ELEMENT_NODE){
                String nodeName = childNode.getNodeName();
                System.out.println(nodeName);
                //拿到属性的值
                //Element是可以有属性和子节点的node。 getAttribute(String)
                Element childElem = (Element)childNode;//易错！！w3c下的Element
                String attribute = childElem.getAttribute("id");
                System.out.println(attribute);
                //以根节点为例  继续找儿子节点
                NodeList nodeList2 = childElem.getChildNodes();
                for(int j=0; j<nodeList2.getLength(); j++){
                    Node node2 = nodeList2.item(j);
                    if(node2.getNodeType() == Node.ELEMENT_NODE){
                        Element sonElem = (Element)node2;
                        String name = sonElem.getNodeName();
                        String value = sonElem.getTextContent();
                        System.out.println(name +"\t"+ value);
                    }
                }
                System.out.println();
            }
        }
    }
}

product2.xml (工程文件上右键  新建  other  XML)

<?xml version="1.0" encoding="UTF-8"?>
<!-- 外部DTD约束 -->
<!DOCTYPE product SYSTEM "product2.dtd">
<product>
    <item id = "P001">
        <name>蜘蛛王皮鞋</name>
        <price>268</price>
        <color>黑色</color>
        <size>42</size>
        <stock>500</stock>
    </item>
    <item id = "P002">
        <name>好皮鞋</name>
        <price>88</price>
        <color>蓝色</color>
        <size>42</size>
        <stock>100</stock>
    </item>
</product>

product2.dtd 新建  XML dtd

<?xml version="1.0" encoding="UTF-8"?>
    <!ELEMENT product (item+)>
    <!ELEMENT item (name,price,color,size,stock)>
    <!ATTLIST item id CDATA #REQUIRED>
    <!ELEMENT name (#PCDATA)>
    <!ELEMENT price (#PCDATA)>
    <!ELEMENT color (#PCDATA)>
    <!ELEMENT size (#PCDATA)>
    <!ELEMENT stock (#PCDATA)>