在java中使用dom4j解析xml

虽然Java中已经有了Dom和Sax这两种标准解析方式

但其操作起来并不轻松，对于我这么一个初学者来说，其中部分代码是活生生的恶心

为此，伟大的第三方开发组开发出了Jdom和Dom4j等工具

鉴于目前的趋势，我们这里来讲讲Dom4j的基本用法，不涉及递归等复杂操作

 往maven中添加的dom4j依赖如下：

<dependency>
            <groupId>dom4j</groupId>
            <artifactId>dom4j</artifactId>
            <version>1.6</version>
        </dependency>

Dom4j的用法很多，官网上的示例有那么点儿晦涩，这里就不写了

首先我们需要出创建一个xml文档，然后才能对其解析

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列表的方式来解析xml

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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

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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

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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：