通过SAX方式生成xml文件

本文简单介绍通过SAX方式生成xml文件的方法。
例子：解析下面的xml文件并生成新的具有同样结构的xml文件

book.xml

<bookstore>
    <book id="1">
        <name>冰与火之歌name>
        <author>乔治马丁author>
        <year>2014year>
        <price>89price>
    book>
    <book id="2">
        <name>安徒生童话name>
        <year>2004year>
        <price>77price>
        <language>Englishlanguage>
    book>
bookstore>

实现代码：
book类：

package com.imooc.entity;

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

    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 getYear() {
        return year;
    }
    public void setYear(String year) {
        this.year = year;
    }
    public String getPrice() {
        return price;
    }
    public void setPrice(String price) {
        this.price = price;
    }
    public String getLanguage() {
        return language;
    }
    public void setLanguage(String language) {
        this.language = language;
    }

}

SAXParserHandler类：

package com.imooc.Handler;

import java.util.ArrayList;

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

import com.imooc.entity.Book;

public class SAXParserHandler extends DefaultHandler {
    int bookIndex=0;
    String value=null;
    Book book=null;
    private ArrayList bookList=new ArrayList();
    public ArrayList getBookList() {
        return bookList;
    }

    /**
     * 用来遍历xml的开始标签
     */
    @Override
    public void startElement(String uri, String localName, String qName,
            Attributes attributes) throws SAXException {
        // TODO Auto-generated method stub
        super.startElement(uri, localName, qName, attributes);
        if(qName.equals("book")){
            book=new Book();
            bookIndex++;
            System.out.println("================开始遍历第"+bookIndex+"本书内容================");
//          //已知book下属性的名称及个数，根据属性名得到属性值
//          String value=attributes.getValue("id");
//          System.out.println("book的属性值是"+value);

            //若不知道book下属性的名称和个数
            int num=attributes.getLength();
            for(int i=0;i"book元素的第"+(i+1)+"个属性名:"
            +attributes.getQName(i));
                System.out.println("--属性值为："+attributes.getValue(i));
                if(attributes.getQName(i).equals("id")){
                    book.setId(attributes.getValue(i));
                }
            }
        }
        else if(!qName.equals("bookstore")){
            System.out.print("结点名是:"+qName);
        }
    }

    /**
     * 用来遍历xml的结束标签
     */
    @Override
    public void endElement(String uri, String localName, String qName)
            throws SAXException {
        // TODO Auto-generated method stub
        super.endElement(uri, localName, qName);
        //判断是否针对一本书已经遍历结束
        if(qName.equals("book")){
            bookList.add(book);
            book=null;
            System.out.println("================结束遍历第"+bookIndex+"本书内容================");
        }
        else if(qName.equals("name")){
            book.setName(value);
        }
        else if(qName.equals("author")){
            book.setAuthor(value);
        }
        else if(qName.equals("year")){
            book.setYear(value);
        }
        else if(qName.equals("price")){
            book.setPrice(value);
        }
        else if(qName.equals("language")){
            book.setLanguage(value);
        }
    }

    /**
     * 用来标识解析开始
     */
    @Override
    public void startDocument() throws SAXException {
        // TODO Auto-generated method stub
        super.startDocument();
        System.out.println("SAX解析开始");
    }

    /**
     * 用来标识解析结束
     */
    @Override
    public void endDocument() throws SAXException {
        // TODO Auto-generated method stub
        super.endDocument();
        System.out.println("SAX解析结束");
    }

    @Override
    public void characters(char[] ch, int start, int length)
            throws SAXException {
        // TODO Auto-generated method stub
        super.characters(ch, start, length);
        value=new String(ch,start,length);
        if(!value.trim().equals("")){
            System.out.println("--结点值为:"+value);
        }
    }

}

SAXTest类：

package com.imooc.test;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Result;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.sax.TransformerHandler;
import javax.xml.transform.stream.StreamResult;

import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;

import com.imooc.Handler.SAXParserHandler;
import com.imooc.entity.Book;

public class SAXTest {

    public ArrayList parseXML() {
        // 获取一个SAXParserFactory的实例
        SAXParserFactory factory = SAXParserFactory.newInstance();
        SAXParserHandler handler = null;
        // 通过factory获取SAXParser实例
        try {
            SAXParser parser = factory.newSAXParser();
            // 创建SAXParserHandler对象
            handler = new SAXParserHandler();
            parser.parse("book.xml", handler);
            System.out
                    .println("~!~!~!共有" + handler.getBookList().size() + "本书");
            for (Book book : handler.getBookList()) {
                System.out.println(book.getId());
                System.out.println(book.getName());
                System.out.println(book.getAuthor());
                System.out.println(book.getYear());
                System.out.println(book.getPrice());
                System.out.println(book.getLanguage());
                System.out.println("-------finish-------");
            }
        } catch (ParserConfigurationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SAXException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return handler.getBookList();
    }

    /**
     * 生成xml
     * 
     * @param args
     */
    public void creatXML() {
        ArrayList bookList = parseXML();
        // 1.创建一个SAXTransformerFactory类的对象
        SAXTransformerFactory tff = (SAXTransformerFactory) SAXTransformerFactory
                .newInstance();
        try {
            // 2.通过SAXTransformerFactory对象创建一个TransformerHandler对象
            TransformerHandler handler = tff.newTransformerHandler();
            // 3.通过handler对象创建一个Transformer对象
            Transformer tf = handler.getTransformer();
            // 4.通过Transformer对象对生成的xml文件进行设置
            // 设置xml的编码
            tf.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
            // 设置xml是否换行
            tf.setOutputProperty(OutputKeys.INDENT, "yes");
            // 5.创建一个Result对象
            File f = new File("newBook.xml");
            if (!f.exists()) {
                f.createNewFile();
            }
            // 6.是result和handler关联
            Result result = new StreamResult(new FileOutputStream(f));
            handler.setResult(result);
            // 7.利用handler对象进行xml文件内容的编写
            // 打开document
            handler.startDocument();
            AttributesImpl attr = new AttributesImpl();
            handler.startElement("", "", "bookstore", attr);
            for (Book book : bookList) {
                //创建book节点
                attr.clear();
                attr.addAttribute("", "", "id", "", book.getId());
                handler.startElement("", "", "book", attr);
                //创建name节点
                if(book.getName()!=null&&!book.getName().trim().equals("")){
                    attr.clear();
                    handler.startElement("", "", "name", attr);
                    handler.characters(book.getName().toCharArray(), 0, book
                        .getName().toCharArray().length);
                    handler.endElement("", "", "name");
                }
                //创建year节点
                if(book.getYear()!=null&&!book.getYear().trim().equals("")){
                    handler.startElement("", "", "year", attr);
                    handler.characters(book.getYear().toCharArray(), 0, book
                        .getYear().toCharArray().length);
                    handler.endElement("", "", "year");
                }
                //创建author节点
                if(book.getAuthor()!=null&&!book.getAuthor().trim().equals("")){
                    handler.startElement("", "", "author", attr);
                    handler.characters(book.getAuthor().toCharArray(), 0, book
                        .getAuthor().toCharArray().length);
                    handler.endElement("", "", "author");
                }
                //创建price节点
                if(book.getPrice()!=null&&!book.getPrice().trim().equals("")){
                    handler.startElement("", "", "price", attr);
                    handler.characters(book.getPrice().toCharArray(), 0, book
                        .getPrice().toCharArray().length);
                    handler.endElement("", "", "price");
                }
                //创建language节点
                if(book.getLanguage()!=null&&!book.getLanguage().trim().equals("")){
                    handler.startElement("", "", "language", attr);
                    handler.characters(book.getLanguage().toCharArray(), 0, book
                        .getLanguage().toCharArray().length);
                    handler.endElement("", "", "language");
                }

                handler.endElement("", "", "book");

            }
            handler.endElement("", "", "bookstore");
            // 关闭document
            handler.endDocument();
        } catch (TransformerConfigurationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SAXException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    public static void main(String[] args) {
        SAXTest st = new SAXTest();
        // st.parseXML();
        st.creatXML();
    }

}

注意：生成xml文件时，setResult()方法一定要写在startDocument()方法之前。