JAVA编码（29）——创建及解析XML文档技术

完场项目在  360云盘：经典详例Demo：创建及解析xml技术

导入jar包：
　　dom4j-1.6.1.jar
   jaxen-1.1-beta-6.jar

项目根目录下，和src并列：创建  User.hbm.xml

<hibernate-mapping>
    <class name="com.bjsxt.user" table="t_user">
        <property name="username"></property>
        <property name="password"></property>
    </class>
</hibernate-mapping>

package com.sinosoft.dom4j;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;

import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

public class TestDom4j {
    
    private static final String fileName = "User.hbm.xml";

    /**
     * 工作中创建xml文档，最常用的framework
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        
        //解析xml文档
        parseXmlDocument();
        
        //创建xml文档
        createXmlDocument();
        
    }
    
    
    
    
    /**
     * 创建xml文档
     * @throws IOException 
     */
    private static void createXmlDocument() throws IOException {
        Document document = DocumentHelper.createDocument();
        Element root = document.addElement("hibernate-mapping");
        Element classElement =  root.addElement("class")
            .addAttribute("name", "com.sinosoft.User")
            .addAttribute("table", "t_user");
        classElement.addElement("property").addAttribute("name", "username");
        
        //普通写出，没有格式
//        FileWriter out = new FileWriter("User1.hbm.xml");
//        document.write(out);
//        out.flush();
//        out.close();
        
        //创建输出格式
        OutputFormat format = OutputFormat.createPrettyPrint();
        XMLWriter writer = new XMLWriter(
                new FileWriter("User1.hbm.xml"), format);
        writer.write(document);
        writer.close();
        
    }




    /**
     * 解析xml文档
     */
    public static void parseXmlDocument(){
        Document document = getDocument(fileName);
        Element rootElement = getRootElement(document);
        System.out.println("根节点名称："+rootElement.getName());
        
        /**
         * 获取根节点-->子节点元素
         */
        for ( Iterator i = rootElement.elementIterator(); i.hasNext(); ) {
            Element element = (Element) i.next();
            System.out.println("根节点下子节点名称："+element.getName());
            /**
             * 获取根节点-->子节点属性
             */
            for ( Iterator j = element.attributeIterator(); j.hasNext(); ) {
                Attribute attribute = (Attribute) j.next();
                System.out.println("属性名称："+attribute.getName()+"    属性值："+attribute.getValue());
            }
            /**
             * 获取根节点-->子节点-->子节点元素
             */
            for (Iterator j = element.elementIterator(); j.hasNext();) {
                Element childElement = (Element) j.next();
                System.out.println("子节点下子节点："+childElement.getName());
                /**
                 * 获取根节点-->子节点-->子节点属性
                 */
                for (Iterator k = childElement.attributeIterator(); k.hasNext();) {
                    Attribute childaAttribute = (Attribute) k.next();
                    System.out.println("子节点下子节点属性名："+childaAttribute.getName()+" 子节点下子节点属性值："+childaAttribute.getValue());
                }
            }
        }
        
        //xpath
        System.out.println("使用xpath进行xml文档的解析");
        List<Node> list = document.selectNodes("//hibernate-mapping/class/property");
        for (Node node : list) {
            System.out.println("节点:"+node.getName());
            System.out.println("节点中name的属性值："+node.valueOf("@name"));
        }
    }
    
    /**
     * 获取文档对象
     * 所谓的 SAX 即为读一点解析一点
     * @param fileName
     * @return
     */
    public static Document getDocument(String fileName){
        Document document = null;
        try {
            SAXReader reader = new SAXReader();
            document = reader.read(new File(fileName));
        } catch (DocumentException e) {
            e.printStackTrace();
        }
        return document;
    }
    
    /**
     * 获取文档节点的根节点
     * Element : 元素
     * @param document
     * @return
     */
    public static Element getRootElement(Document document){
        return document.getRootElement();
    }
}