【xml之Dom4j解析】_no protocol: <?xml version="1.0" encoding="gb2312"-优快云博客

本文介绍使用DOM4J库进行XML文件的基本操作，包括读取、添加、更新及删除节点等过程。通过实例演示了如何定位特定元素，并对XML文档进行修改。

book.xml

<?xml version="1.0" encoding="gb2312"?>
<!DOCTYPE 书架 SYSTEM "book.dtd">

<书架>
  <书>
    <书名 name="xxx">Java就业培训教程</书名>
    <作者>张孝祥</作者>
  </书>
  <书>
    <书名 name="yyy">JavaScript网页开发</书名>
    <作者>5</作者>
    <售价>28.00元</售价>
  </书>
</书架>

demo.java

import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.OutputStreamWriter;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
import org.junit.Test;



public class demo1 {  

    //读第 1本书的信息   
    @Test  
    public void read() throws Exception  
    {  
         SAXReader reader = new SAXReader();  
         Document document = reader.read("book.xml");  
         Element book= (Element) document.getRootElement().elements("书").get(0);  
         String value=book.element("书名").getText();  
         String attributeValue=book.element("书名").attributeValue("name");  
         System.out.println(value  +";"+attributeValue);  
    }  
    
    //在第一本上添加一个新的售价  
    @Test  
    public void add() throws Exception{  
        SAXReader reader=new SAXReader();  
        Document document=reader.read(new File("book.xml"));  
        Element book=document.getRootElement().element("书");  
        book.addElement("售价").setText("222");     
          
          
        OutputFormat format = OutputFormat.createPrettyPrint();  
        format.setEncoding("gb2312");  
        XMLWriter writer=new XMLWriter(new FileOutputStream("book.xml"), format);  
        writer.write(document);  
        writer.close();  
    }  
      
    //在第一本书指定位置上添加一个新的售价,更改List集合  
    @Test  
    public void add2() throws Exception{  
        SAXReader reader=new SAXReader();  
        Document document=reader.read(new File("book.xml"));  
          
        Element book=document.getRootElement().element("书");  
        List list=book.elements();//[书名，作者，售价]  
          
        Element price=DocumentHelper.createElement("售价0");  
        price.setText("309元");  
        list.add(0,price);    
          
        OutputFormat format = OutputFormat.createPrettyPrint();  
        format.setEncoding("gb2312");  
        XMLWriter writer=new XMLWriter(new FileOutputStream("book.xml"), format);  
        writer.write(document);  
        writer.close();  
    }  
    
    //删除上面的节点  
    @Test  
    public void delete() throws Exception {  
        SAXReader reader=new SAXReader();  
        Document document=reader.read(new File("book.xml"));  
        Element price=document.getRootElement().element("书").element("售价");  
        price.getParent().remove(price);  
        
        OutputFormat format = OutputFormat.createPrettyPrint();  
        format.setEncoding("gb2312");  
        XMLWriter writer=new XMLWriter(new FileOutputStream("book.xml"), format);  
        writer.write(document);  
        writer.close(); 
    }  
    
    //更新节点  
    @Test  
    public void update() throws Exception{  
        SAXReader reader=new SAXReader();  
        Document document=reader.read(new File("book.xml"));  
      
        Element book=(Element) document.getRootElement().elements("书").get(1);  
        book.element("作者").setText("5");  
          
        OutputFormat format = OutputFormat.createPrettyPrint();  
        format.setEncoding("gb2312");  
        XMLWriter writer=new XMLWriter(new FileOutputStream("book.xml"), format);  
        writer.write(document);  
        writer.close();       
    }  
}

解决乱码问题：

//        format.setEncoding("gb2312");  
//        XMLWriter writer=new XMLWriter(new FileWriter("book.xml"), format);//因为FileWriter的默认编码是gb2312，所以format的编码格式只能设置成gb2312
        
//        format.setEncoding("utf-8"); //gb2312 
//        XMLWriter writer=new XMLWriter(new OutputStreamWriter(new FileOutputStream("book.xml"),"utf-8"), format);//gb2312 
        
//        format.setEncoding("utf-8");//gb2312 
//        XMLWriter writer=new XMLWriter(new FileOutputStream("book.xml"), format);//FileOutputStream会去查format的编码