在java中运用dom4j剖析xml(示例代码)【XML教程】,java dom4j xml

虽然Java中已经有了Dom和Sax这两种规范剖析体式格局

但其操纵起来并不轻松，关于我这么一个初学者来讲，个中部份代码是活生生的恶心

为此，巨大的第三方开辟组开辟出了Jdom和Dom4j等东西

鉴于现在的趋向，我们这里来讲讲Dom4j的基础用法，不触及递归等庞杂操纵

Dom4j的用法许多，官网上的示例有那么点儿艰涩，这里就不写了

起首我们须要出建立一个xml文档，然后才能对其剖析

xml文档：

<?xml version="1.0" encoding="UTF-8"?> 
<books> 
   <book id="001"> 
      <title>Harry Potter</title> 
      <author>J K. Rowling</author> 
   </book> 
   <book id="002"> 
      <title>Learning XML</title> 
      <author>Erik T. Ray</author> 
   </book> 
</books>

示例一：用List列表的体式格局来剖析xml

import java.io.File;
import java.util.List;
import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
public class Demo {
 public static void main(String[] args) throws Exception {
  SAXReader reader = new SAXReader();
  File file = new File("books.xml");
  Document document = reader.read(file);
  Element root = document.getRootElement();
  List<Element> childElements = root.elements();
  for (Element child : childElements) {
   //未知属性名情况下
   /*List<Attribute> attributeList = child.attributes();
   for (Attribute attr : attributeList) {
    System.out.println(attr.getName() + ": " + attr.getValue());
   }*/

   //已知属性名情况下
   System.out.println("id: " + child.attributeValue("id"));

   //未知子元素名情况下
   /*List<Element> elementList = child.elements();
   for (Element ele : elementList) {
    System.out.println(ele.getName() + ": " + ele.getText());
   }
   System.out.println();*/

   //已知子元素名的情况下
   System.out.println("title" + child.elementText("title"));
   System.out.println("author" + child.elementText("author"));
   //这行是为了花样化雅观而存在
   System.out.println();
  }
 }
}

示例二：运用Iterator迭代器的体式格局来剖析xml

import java.io.File;
import java.util.Iterator;
import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
public class Demo {
 public static void main(String[] args) throws Exception {
  SAXReader reader = new SAXReader();
  Document document = reader.read(new File("books.xml"));
  Element root = document.getRootElement();

  Iterator it = root.elementIterator();
  while (it.hasNext()) {
   Element element = (Element) it.next();

   //未知属性称号情况下
   /*Iterator attrIt = element.attributeIterator();
   while (attrIt.hasNext()) {
    Attribute a  = (Attribute) attrIt.next();
    System.out.println(a.getValue());
   }*/

   //已知属性称号情况下
   System.out.println("id: " + element.attributeValue("id"));

   //未知元素名情况下
   /*Iterator eleIt = element.elementIterator();
   while (eleIt.hasNext()) {
    Element e = (Element) eleIt.next();
    System.out.println(e.getName() + ": " + e.getText());
   }
   System.out.println();*/

   //已知元素名情况下
   System.out.println("title: " + element.elementText("title"));
   System.out.println("author: " + element.elementText("author"));
   System.out.println();
  }
 }
}

运转效果：

示例三：建立xml文档并输出到文件

import java.io.File;
import java.io.FileOutputStream;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;

public class Demo {
 public static void main(String[] args) throws Exception {
  Document doc = DocumentHelper.createDocument();
  //增添根节点
  Element books = doc.addElement("books");
  //增添子元素
  Element book1 = books.addElement("book");
  Element title1 = book1.addElement("title");
  Element author1 = book1.addElement("author");

  Element book2 = books.addElement("book");
  Element title2 = book2.addElement("title");
  Element author2 = book2.addElement("author");

  //为子节点增加属性
  book1.addAttribute("id", "001");
  //为元素增加内容
  title1.setText("Harry Potter");
  author1.setText("J K. Rowling");

  book2.addAttribute("id", "002");
  title2.setText("Learning XML");
  author2.setText("Erik T. Ray");

  //实例化输出花样对象
  OutputFormat format = OutputFormat.createPrettyPrint();
  //设置输出编码
  format.setEncoding("UTF-8");
  //建立须要写入的File对象
  File file = new File("D:" + File.separator + "books.xml");
  //生成XMLWriter对象，组织函数中的参数为须要输出的文件流和花样
  XMLWriter writer = new XMLWriter(new FileOutputStream(file), format);
  //最先写入，write要领中包括上面建立的Document对象
  writer.write(doc);
 }
}

运转效果：