Java 操作XML[方式二] (org.xml.sax)

• SAX
  • SimpleAPI for XML
  • 采用事件/流模型来解析XML文档, 更快速, 更轻量
  • 有选择解析和访问, 不像DOM加载整个文档, 内存要求低
  • SAX 对 XML 文档的解析为一次性读取, 不创建/存储文档对象, 很难同时访问xml文档中多处数据
  • 推模型. 当它每发现一个节点就引发一个事件, 而我们需要编写这些事件的处理程序.

package hello;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.XMLReaderFactory;

import java.util.ArrayList;
import java.util.List;

public class XML_SAXReader {
    public static void main(String[] args) {
        try {
            XMLReader parser = XMLReaderFactory.createXMLReader();
            UserHandler userHandler = new UserHandler();
            parser.setContentHandler(userHandler);
            parser.parse("users.xml");
            System.out.println(userHandler.getNameList());

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    static class UserHandler extends DefaultHandler {
        private List<String> nameList;
        private boolean isName = false;

        public List<String> getNameList() {
            return nameList;
        }

        public void startDocument() throws SAXException {
            System.out.println("开始解析文档...");
            this.nameList = new ArrayList<String>();
        }

        // xml 文档解析结束
        public void endDocument() throws SAXException {
            System.out.println("...文档解析完毕");
        }

        // 访问某一个元素
        public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {
            System.out.println("开始读取标签 " + qName);
            if (qName.equals("name")) {
                isName = true;
            }
        }

        // 结束访问元素
        public void endElement(String namespaceURI, String localName, String qName) throws SAXException {
            System.out.println("结束读取标签 " + qName);
            if (isName) {
                isName = false;
            }
        }

        // 访问元素正文
        public void characters(char[] ch, int start, int length) {
            if (isName) {
                String name = new String(ch, start, length);
                System.out.println("userName: " + name);
                nameList.add(name);
            }
        }

    }
}

<?xml version="1.0" encoding="UTF-8"?>
<users>
    <user id="001">
        <name>Mary</name>
        <age>3</age>
        <sex>Female</sex>
    </user>
    <user id="002">
        <name>Mike</name>
        <age>18</age>
        <sex>Male</sex>
    </user>
    <user id="003">
        <name>ZhaZhaHui</name>
        <age>38</age>
        <sex>Male</sex>
    </user>
</users>