XML生成（二）：SAX生成XML

港控/mmm° 2022-06-10 14:21 302阅读 0赞

# SAX生成XML文件的基本流程 #

1.创建SAXTransformerFactor对象

2.通过SAXTransformerFactor对象创建TransformerHandler对象

3.通过TransformerHandler对象创建Transformer对象

4.创建Result对象，与目的文件关联，并将此对象与TransformerHandler对象关联

5.创建AttributesImpl对象（此对象为节点的属性）

6.使用TransformerHandler对象的startDocument()开始文档，文档编写结束后调用endDocument()方法结束文档

7.使用TransformerHandler对象的startElement()开始元素，此方法有四个参数（名称空间URI,本地名称localName,限定名qName，连接到元素的属性Atrributes）；元素结束后调用endElement()方法结束对应元素，此方法有三个参数（名称空间URI,本地名称localName,限定名qName）

8.使用TransformerHandler对象的characters()方法为每个元素设置文本数据

# 示例 #

本示例是基于解析book.xml文件所得结果进行生成

package wds.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 wds.entity.Book;
    import wds.handler.SAXParserHandler;
    
    public class SAXCreateXML {
    
        /** * @param args */
        public ArrayList<Book> parseXML() {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            SAXParserHandler handler = null;
            try {
                SAXParser parser = factory.newSAXParser();
                handler = new SAXParserHandler();
                parser.parse("book.xml", handler);
                System.out.println("···········共有" + handler.getList().size()
                        + "本书···········");
                for (Book book : handler.getList()) {
                    System.out.println(book.toString());
                }
            } 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.getList();
        }
    
        public void createXML() {
            // 解析所得Book的list集合
            ArrayList<Book> bookList = parseXML();
            // 1.创建一个SAXTransformerFactor类对象
            SAXTransformerFactory tff = (SAXTransformerFactory) SAXTransformerFactory
                    .newInstance();
            try {
                // 2.通过TransformerFactory对象创建TransformerHandler对象
                // newTransformerHandler()此方法获取能够将SAX
                // ContentHandler事件处理为Result的TransformerHandler对象
                TransformerHandler handler = tff.newTransformerHandler();
                // 3. 创建Transformer对象 Transformer为抽象类 此类的实例能够将源树转换为结果树
                Transformer tf = handler.getTransformer();
                // 4 .通过transformer对象对xml文件进行 配置
                // 设置编码
                tf.setOutputProperty(OutputKeys.ENCODING, "utf-8");
                // 设置是否换行
                tf.setOutputProperty(OutputKeys.INDENT, "yes");
                // 设置目的文件
                File f = new File("src/res/newbook.xml");
                // 若文件不存在，新创建一个
                if (!f.exists()) {
                    f.createNewFile();
                }
                // 5. 创建Result对象将目的文件与之关联
                Result result = new StreamResult(new FileOutputStream(f));
                // 将Result对象与handler关联
                handler.setResult(result);
                // 6.利用handler对象对xml内容进行编写
                // 打开document
                handler.startDocument();
                // 属性对象
                AttributesImpl attr = new AttributesImpl();
                handler.startElement("", "", "bookstore", attr);
                for (Book book : bookList) {
                    // 每次使用属性对象，将其清空
                    attr.clear();
                    // 为book属性赋值
                    attr.addAttribute("", "", "id", "", book.getId());
                    handler.startElement("", "", "book", attr);
                    if (book.getName() != null && !book.getName().trim().equals("")) {
                        attr.clear();
                        handler.startElement("", "", "name", attr);
                        handler.characters(book.getName().toCharArray(), 0, book
                                .getName().length());
                        handler.endElement("", "", "name");
                    }
                    if (book.getAuthor() != null
                            && !book.getAuthor().trim().equals("")) {
                        handler.startElement("", "", "author", attr);
                        handler.characters(book.getAuthor().toCharArray(), 0, book
                                .getAuthor().length());
                        handler.endElement("", "", "author");
                    }
                    if (book.getYear() != null && !book.getYear().trim().equals("")) {
                        handler.startElement("", "", "year", attr);
                        handler.characters(book.getYear().toCharArray(), 0, book
                                .getYear().length());
                        handler.endElement("", "", "year");
                    }
                    if (book.getPrice() != null
                            && !book.getPrice().trim().equals("")) {
                        handler.startElement("", "", "price", attr);
                        handler.characters(book.getPrice().toCharArray(), 0, book
                                .getPrice().length());
                        handler.endElement("", "", "price");
                    }
                    handler.endElement("", "", "book");
                }
    
                handler.endElement("", "", "bookstore");
                // 关闭document
                handler.endDocument();
            } catch (TransformerConfigurationException e) {
                e.printStackTrace();
            } catch (FileNotFoundException e) {
                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) {
            // TODO Auto-generated method stub
    
            new SAXCreateXML().createXML();
        }
    
    }

### 生成的XML文件 ###

newbook.xml

<?xml version="1.0" encoding="utf-8"?><bookstore>
    <book id="1">
    <name>java编程思想</name>
    <author>Bruce Eckel</author>
    <year>2015</year>
    <price>79</price>
    </book>
    <book id="2">
    <name>深入理解java虚拟机</name>
    <author>周志明</author>
    <price>40</price>
    </book>
    </bookstore>