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();

            }

        }

    }

}

<?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>

<?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)>