根据xml的标签解析文件的Demo

package xmlExtractor;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;import java.util.ArrayList;import java.util.List;public class SAXHandler extends DefaultHandler {    int bookIndex = 0;    private List<Book> bookList = new ArrayList<Book>();    private Book book = null;    private String value = null;    //用来标志解析开始    @Override    public void startDocument() throws SAXException {        System.out.println("解析开始");    }    //用来标志解析结束    @Override    public void endDocument() throws SAXException {        System.out.println("解析结束");    }    //用来遍历元素    //开始标签    @Override    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {        if (qName.equals("book")) {            bookIndex++;            book = new Book();            System.out.println("============================第" + bookIndex + "本书开始了=========================");            //已知book下属性元素的名称            //System.out.println(attributes.getValue("id"));            for (int i = 0; i < attributes.getLength(); i++) {                String name = attributes.getQName(i);                if (name.equals("id")) {                    book.setId(attributes.getValue(i));                } else if (name.equals("class")) {                    book.setClassName(attributes.getValue(i));                }                book.setId(attributes.getValue(i));                //System.out.println(name);                System.out.println("第" + bookIndex + "本书的" + attributes.getQName(i) + "是:" + attributes.getValue(i)/*attributes.getValue(Qname)*/);            }        } else if (!qName.equals("bookStore")) {            System.out.print("第" + bookIndex + "本书的" + qName + "是:");        }    }    //遍历标签内的内容    @Override    public void characters(char[] ch, int start, int length) throws SAXException {        value = new String(ch, start, length);        //如果标签下没有内容，如bookstore与book之间就没有内容，将不打印        if (!value.trim().equals("")) {            System.out.println(value);        }    }    //遍历元素的结束标签    @Override    public void endElement(String uri, String localName, String qName) throws SAXException {        if (qName.equals("book")) {            bookList.add(book);            book = null;            System.out.println("============================第" + bookIndex + "本书结束了=========================");        } else if (qName.equals("name")) {            book.setName(value);        } else if (qName.equals("author")) {            book.setAuthor(value);        } else if (qName.equals("year")) {            book.setYear(value);        }    }    public List<Book> getBookList() {        return bookList;    }}