使用SAX解析将xml的文件内容结构保存到java对象中

在Java使用Sax解析xml文件中，我们介绍了如何用SAX解析xml文件，接下来我们继续学习如何将一个xml文件的内容结构保存到一个java实例对象中

一、xml文件如下

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
	<book id="156">
		<name>计算机网络</name>
		<author>谢希仁</author>
		<price>39</price>
		<year>2013</year>
	</book>
	<book id="234">
		<name>计算机操作系统</name>
		<author>佚名</author>
		<price>40</price>
		<year>2013</year>
		<edition>第四版</edition>
	</book>
	<book id="367">
		<name>计算机组成原理</name>
		<price>35</price>
		<year>2013</year>
		<edition>第三版</edition>
	</book>
</bookstore>

二、首先，我们要想写一个与xml中的book节点结构相同的 实体类Book

public class Book {
	private String id;
	private String name;
	private String author;
	private String price;
	private String year;
	private String edition;

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAuthor() {
		return author;
	}

	public void setAuthor(String author) {
		this.author = author;
	}

	public String getPrice() {
		return price;
	}

	public void setPrice(String price) {
		this.price = price;
	}

	public String getYear() {
		return year;
	}

	public void setYear(String year) {
		this.year = year;
	}

	public String getEdition() {
		return edition;
	}

	public void setEdition(String edition) {
		this.edition = edition;
	}

	@Override
	public String toString() {
		return "Book [id=" + id + ", name=" + name + ", author=" + author + ", price=" + price + ", year=" + year
				+ ", edition=" + edition + "]";
	}

}

三、编写DefaultHandler类

使用全局变量来实现不同函数之间的对象共享

public class MyHandler extends DefaultHandler {
	private String value = null;
	private List<Book> bookList = new ArrayList<>();
	private Book book = null;

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

	@Override
	public void characters(char[] ch, int start, int length) throws SAXException {
		super.characters(ch, start, length);
		value = new String(ch, start, length);

	}

	@Override
	public void endElement(String uri, String localName, String qName) throws SAXException {
		super.endElement(uri, localName, qName);
		switch (qName) {
		case "book":
			bookList.add(book);
			book = null;
			break;
		case "name":
			book.setName(value);
			break;
		case "author":
			book.setAuthor(value);
		case "year":
			book.setYear(value);
			break;
		case "edition":
			book.setEdition(<span style="font-family: Arial, Helvetica, sans-serif; font-size: 12px;">value</span><span style="font-size: 12px; font-family: Arial, Helvetica, sans-serif;">);</span>
			break;
		case "price":
			book.setPrice(value);
			break;
		}
	}

	public List<Book> getBookList() {
		return bookList;
	}

	public void setBookList(List<Book> bookList) {
		this.bookList = bookList;
	}

}

四、编写主函数

public class SaxXmlParser {
	public static void main(String[] args) {
		// 创建SAXParserFactory实例
		SAXParserFactory spf = SAXParserFactory.newInstance();
		try {
			// 创建SAXParser实例
			SAXParser parser = spf.newSAXParser();
			// 创建DefaultHandler实例
			MyHandler handler = new MyHandler();
			// 开始解析
			parser.parse("book.xml", handler);
			for (Book book : handler.getBookList()) {
				System.out.println(book);
			}
		} catch (ParserConfigurationException | SAXException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

五、控制台输出结果如下

Book [id=156, name=计算机网络, author=谢希仁, price=39, year=2013, edition=null]
Book [id=234, name=计算机操作系统, author=佚名, price=40, year=2013, edition=第四版]
Book [id=367, name=计算机组成原理, author=null, price=35, year=2013, edition=第三版]