<?xml version="1.0" encoding="gbk" ?>
<person>
    <name>张三</name>
    <age>23</age>
</person>  

<?xml version="1.0" encoding="utf-8" ?>
<?xml-stylesheet type="text/css" href="./demo.css" ?>
<person>
    <name>张三</name>
    <age>23</age>
</person>  

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE person SYSTEM "demo.dtd">
<person>
    <name>张三</name>
    <age>23</age>
</person>

<!ELEMENT person (name+, age?, sex, school*)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT age (#PCDATA)>
<!ELEMENT sex EMPTY>
<!ELEMENT school ANY>

<! ATTLIST 元素名称
    属性名称 属性类型 属性的约束
>

interface Node{
    // 添加节点
    public Node appendChild(Node newChild);
    // 移除节点
    public Node removeChild(Node oldChild);
    // 获取父节点
    public Node getParentNode();
    // 返回文本内容
    public String getTextContent()
}
interface NodeList{
    // 通过下标获取具体值
    public Node item(int index);
    // 得到集合长度
    public int getLength();
}
interface Document extends Node{
    // 获取标签
    public NodeList getElementsByTagName(String tagname);
    // 创建标签
    public Element createElement(String tagName);
    // 创建文本
    public Text createTextNode(String data);
}
abstract DocumentBuilder{
    public Document parse(File f)
}
abstract DocumentBuilderFactory{
    public static DocumentBuilderFactory newInstance()
    public abstract DocumentBuilder newDocumentBuilder()
}
abstract class SAXParser{}
abstract class SAXParserFactory{}

<?xml version="1.0" encoding="utf-8" ?>
<list>
    <person>
        <name>张三</name>
        <age>23</age>
    </person>
    <person>
        <name>李四</name>
        <age>24</age>
    </person>
</list>

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
public class Demo {
    /**
     * 1、创建解析器工厂
     * 2、根据解析器工厂创建解析器
     * 3、解析xml返回document
     *
     */
    public static void main(String[] args) throws Exception {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document document = builder.parse("demo.xml");
        NodeList list = document.getElementsByTagName("name");
        for (int i = 0; i < list.getLength(); i++) {
            Node node = list.item(i);
            String name = node.getTextContent();
            System.out.println(name);
            // 张三 李四
        }
    }
}

package util;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import java.io.IOException;
public class DocumentUtil {
    public static Document loadXml(String filename) throws ParserConfigurationException, IOException, SAXException {
        // 创建解析器工厂
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        // 根据解析器工厂创建解析器
        DocumentBuilder builder = factory.newDocumentBuilder();
        // 解析xml返回document
        return builder.parse(filename);
    }
    public static void dumpXml(String filename, Document document) throws TransformerException {
        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        Transformer transformer = transformerFactory.newTransformer();
        transformer.transform(new DOMSource(document), new StreamResult(filename));
    }
}

import org.w3c.dom.*;
import util.DocumentUtil;
public class Demo {
    public static void main(String[] args) throws Exception {
        String filename = "demo.xml";
        // 读取
        Document document = DocumentUtil.loadXml(filename);
        // 查询节点
        NodeList list = document.getElementsByTagName("name");
        Node node = list.item(0);
        // 设置节点内容
        node.setTextContent("大壮");
        // 删除节点
        Node parentNode = node.getParentNode();
        parentNode.removeChild(node);
        // 回写到硬盘
        DocumentUtil.dumpXml(filename, document);
    }
}

<complexType>
    <sequence>
        <element name="name" type="string"></element>
        <element name="age" type="int"></element>
    </sequence>
</complexType>

表示被约束文档，别名xsi
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
路径地址
xsi:schemaLocation="http://www.w3school.com.cn demo.xsd">

<attribute name="age" type="int" use="required"></attribute>

package org.xml.sax;
public class HandlerBase{
    public void startElement (String name, AttributeList attributes);
    public void characters (char ch[], int start, int length);
    public void endElement (String name);
}
package org.xml.sax.helpers;
public class DefaultHandler{
    public void startElement (String uri, String localName,
                              String qName, Attributes attributes)    
    public void endElement (String uri, String localName, String qName)
    public void characters (char ch[], int start, int length)
}