SAX解析xml文件

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

<bookshelf>
    <book>
        <name bookname="thinkinjava">Think in Java</name>
        <author>Bruce Eckel</author>
        <price>95.00</price>
    </book>
    <book>
        <name>Effective Java</name>
        <author>Joshua Bloch</author>
        <price>52.00</price>
    </book>
</bookshelf>

import org.xml.sax.*;
import org.xml.sax.helpers.DefaultHandler;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

public class SaxDemo {

    public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException {

        SAXParserFactory factory = SAXParserFactory.newInstance();

        SAXParser parser = factory.newSAXParser();

        XMLReader reader = parser.getXMLReader();

        /*reader.setContentHandler(new ListHandle());*/
        /*reader.setContentHandler(new TagValueHandle());*/
        BeanListHandle beanListHandle = new BeanListHandle();
        reader.setContentHandler(beanListHandle);

        reader.parse("day02/src/book.xml");

        List<Book> list = beanListHandle.getList();
        System.out.println(list);
    }

}

// 遍历读取xml文件
class ListHandle implements ContentHandler {

    @Override
    public void setDocumentLocator(Locator locator) {

    }

    @Override
    public void startDocument() throws SAXException {

    }

    @Override
    public void endDocument() throws SAXException {

    }

    @Override
    public void startPrefixMapping(String prefix, String uri) throws SAXException {

    }

    @Override
    public void endPrefixMapping(String prefix) throws SAXException {

    }

    @Override
    public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {
        System.out.println("<" + qName + ">");

        // 标签属性
        for (int i = 0; atts != null && i < atts.getLength(); i++) {
            String name = atts.getQName(i);
            String value = atts.getValue(i);
            System.out.println(name + " - " + value);
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        System.out.println("</" + qName + ">");
    }

    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        System.out.println(new String(ch, start, length));
    }

    @Override
    public void ignorableWhitespace(char[] ch, int start, int length) throws SAXException {

    }

    @Override
    public void processingInstruction(String target, String data) throws SAXException {

    }

    @Override
    public void skippedEntity(String name) throws SAXException {

    }
}

// 获取指定标签的值
class TagValueHandle extends DefaultHandler {

    private String currentTag; // 当前解析的标签
    private Integer currentIndex = 0; // 当前解析顺序

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        currentTag = qName;
        if (currentTag.equals("author")) {
            currentIndex++;
        }
    }

    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        Integer index = 1; // 需要第一个标签的值
        if (currentTag != null && currentTag.equals("author") && Objects.equals(currentIndex, index)) {
            System.out.println(new String(ch, start, length));
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        currentTag = null;
    }
}

// xml对象封装为Bean
class BeanListHandle extends DefaultHandler {

    private List<Book> list = new ArrayList<>();
    private String currentTag;
    private Book book;

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        currentTag = qName;
        if (currentTag.equals("book")) {
            book = new Book();
        }
    }

    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        if (currentTag != null && currentTag.equals("name")) {
            book.setName(new String(ch, start, length));
        }
        if (currentTag != null && currentTag.equals("author")) {
            book.setAuthor(new String(ch, start, length));
        }
        if (currentTag != null && currentTag.equals("price")) {
            book.setPrice(new String(ch, start, length));
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        currentTag = null;
        if (qName.equals("book")) {
            list.add(book);
            book = null;
        }
    }

    public List<Book> getList() {
        return list;
    }
}