java中采用dom4j解析xml文件

2022-10-13 18:38:42

一.前言

在最近的开发中用到了dom4j来解析xml文件，以前听说过来解析xml文件的几种标准方式；但是从来的没有应用过来，所以可以在google中搜索dmo4j解析xml文件的方式，学习一下dom4j解析xml的具体操作。

二.代码详情

dom4j是一个第三方开发组开发出的插件，所以在我们使用dom4jf的时候我们要去下载一下dom4j对应版本的jar导入在我们项目中。

1)xml文件:

<?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列表的方式来解析xml

SAXReader就是一个管道，用一个流的方式，把xml文件读出来

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"));

            //这行是为了格式化美观而存在

            System.out.println();

        }

    }

}

示例二：使用Iterator迭代器的方式来解析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();

            //未知属性名称情况下

            /*Iterator attrIt = element.attributeIterator();

            while (attrIt.hasNext()) {

                Attribute a  = (Attribute) attrIt.next();

                System.out.println(a.getValue());

            }*/

            //已知属性名称情况下

            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();

        }

    }

}

运行结果：

示例三：创建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();

        //增加根节点

        Element books = doc.addElement("books");

        //增加子元素

        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");

        //为子节点添加属性

        book1.addAttribute("id", "001");

        //为元素添加内容

        title1.setText("Harry Potter");

        author1.setText("J K. Rowling");

        book2.addAttribute("id", "002");

        title2.setText("Learning XML");

        author2.setText("Erik T. Ray");

        //实例化输出格式对象

        OutputFormat format = OutputFormat.createPrettyPrint();

        //设置输出编码

        format.setEncoding("UTF-8");

        //创建需要写入的File对象

        File file = new File("D:" + File.separator + "books.xml");

        //生成XMLWriter对象，构造函数中的参数为需要输出的文件流和格式

        XMLWriter writer = new XMLWriter(new FileOutputStream(file), format);

        //开始写入，write方法中包含上面创建的Document对象

        writer.write(doc);

    }

}

运行结果：

码农公寓

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