DOM4J介绍与代码示例 （强大的xml处理工具）

DOM4J是dom4j.org出品的一个开源XML解析包。Dom4j是一个易用的、开源的库，用于XML，XPath和XSLT。它应用于Java平台，采用了Java集合框架并完全支持DOM，SAX和JAXP。关键 牛逼的 oracle 也在使用。

DOM4J下载jar包：http://downloads.sourceforge.net/dom4j/dom4j-1.6.1.jar

JAXEN（对XPath的支持）：http://dist.codehaus.org/jaxen/distributions/jaxen-1.1.1.zip

1.DOM4J主要接口

DOM4J主要接口都在org.dom4j这个包里定义。

 

-Node为所有的dom4j中XML节点定义了多态行为；

-Branch为能够包含子节点的节点如XML元素(Element)和文档(Docuemnts)定义了一个公共的行为；

|-Element 定义XML 元素；

|-Document定义了XML文档；

 

-DocumentType 定义XML DOCTYPE声明；

-Entity定义 XML entity；

-Attribute定义了XML的属性；

-ProcessingInstruction 定义 XML 处理指令；

-CharacterData是一个标识借口，标识基于字符的节点。如CDATA，Comment, Text；

|- CDATA 定义了XML CDATA 区域；

|-Text 定义XML 文本节点；

|- Comment 定义了XML注释的行为；

项目结构

 

maven代码

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">  <modelVersion>4.0.0</modelVersion>  <groupId>lqy</groupId>  <artifactId>Dom4jTest</artifactId>  <version>0.0.1-SNAPSHOT</version>  <packaging>jar</packaging>  <name>Dom4jTest</name>  <url>http://maven.apache.org</url>  <properties>    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>  </properties>  <dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>3.8.1</version>      <scope>test</scope>    </dependency>    <dependency>        <groupId>dom4j</groupId>        <artifactId>dom4j</artifactId>        <version>1.6.1</version>    </dependency>    <dependency>        <groupId>jaxen</groupId>        <artifactId>jaxen</artifactId>        <version>1.1.4</version>    </dependency>  </dependencies></project>

 

1.创建XML文档

package lqy.Dom4jTest;import java.io.File;import java.io.FileWriter;import java.io.IOException;import java.util.HashMap;import java.util.Map; import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.DocumentHelper;import org.dom4j.Element;import org.dom4j.io.OutputFormat;import org.dom4j.io.XMLWriter; /* * 创建XML文档 */public class XmlGen {        /*     * 方法generateDocumentByMethod()通过调用方法构建xml文档：        1.使用DocumentHelper得到Document实例        Document document = DocumentHelper.createDocument();        2.创建Processing Instruction        document.addProcessingInstruction("xml-stylesheet", inMap);        3.创建元素Element        Element studentsElement = document.addElement("students");        4.为元素添加注释Comment        studentsElement.addComment("An Student Catalog");        5.为元素添加属性        studentsElement.addComment("An Student Catalog");        6.为元素添加文本值Text        ageElement.setText("18");     */    public Document generateDocumentByMethod() {               Document document = DocumentHelper.createDocument();       // ProcessingInstruction       Map<String, String> inMap = new HashMap<String, String>();       inMap.put("type", "text/xsl");       inMap.put("href", "students.xsl");       document.addProcessingInstruction("xml-stylesheet", inMap);       // root element       Element studentsElement = document.addElement("students");       studentsElement.addComment("An Student Catalog");       // son element       Element stuElement = studentsElement.addElement("student");       stuElement.addAttribute("sn", "01");       Element nameElement = stuElement.addElement("name");       nameElement.setText("sam");       Element ageElement = stuElement.addElement("age");       ageElement.setText("18");       // son element       Element anotherStuElement = studentsElement.addElement("student");       anotherStuElement.addAttribute("sn", "02");       Element anotherNameElement = anotherStuElement.addElement("name");       anotherNameElement.setText("lin");       Element anotherAgeElement = anotherStuElement.addElement("age");       anotherAgeElement.setText("20");        return document;    }         /*     * 方法generateDocumentByString()通过字符串转换直接构建xml文档，使用DocumentHelper.parseText()来实现.     * document = DocumentHelper.parseText(text);     */    public Document generateDocumentByString() {       String text = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>" +              "<?xml-stylesheet type=\"text/xsl\" href=\"students.xsl\"?>" +              "<students><!--An Student Catalog-->   <student sn=\"01\">" +              "<name>sam</name><age>18</age></student><student sn=\"02\">" +              "<name>lin</name><age>20</age></student></students>";       Document document = null;       try {           document = DocumentHelper.parseText(text);       } catch (DocumentException e) {           e.printStackTrace();       }       return document;    }     public void saveDocument(Document document, File outputXml) {       try {           // 美化格式           OutputFormat format = OutputFormat.createPrettyPrint();           /*// 缩减格式           OutputFormat format = OutputFormat.createCompactFormat();*/           /*// 指定XML编码            format.setEncoding("GBK");*/           XMLWriter output = new XMLWriter(new FileWriter(outputXml), format);           output.write(document);           output.close();       } catch (IOException e) {           System.out.println(e.getMessage());       }    }     public static void main(String[] argv) {       XmlGen dom4j = new XmlGen();       Document document = null;        //通过方法生成        document=dom4j.generateDocumentByMethod();                //通过字符串生成        //document = dom4j.generateDocumentByString();               dom4j.saveDocument(document, new File("students-gen.xml"));    }}

 

生成students-gen.xml如下

<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="students.xsl"?><students>  <!--An Student Catalog-->  <student sn="01">    <name>sam</name>    <age>18</age>  </student>  <student sn="02">    <name>lin</name>    <age>20</age>  </student></students>

 

方法generateDocumentByMethod()通过调用方法构建xml文档：

1.使用DocumentHelper得到Document实例

Document document = DocumentHelper.createDocument();

2.创建Processing Instruction

document.addProcessingInstruction("xml-stylesheet", inMap);

3.创建元素Element

Element studentsElement = document.addElement("students");

4.为元素添加注释Comment

studentsElement.addComment("An Student Catalog");

5.为元素添加属性

studentsElement.addComment("An Student Catalog");

6.为元素添加文本值Text

ageElement.setText("18");

 

方法generateDocumentByString()通过字符串转换直接构建xml文档，使用DocumentHelper.parseText()来实现.

document = DocumentHelper.parseText(text);

 

方法saveDocument(Document document, File outputXml)将文档输出到文件保存，可指定字符编码，可指定格式化输出。

2.修改XML文档

package lqy.Dom4jTest;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.Element;import org.dom4j.Node;import org.dom4j.io.SAXReader;import org.dom4j.io.XMLWriter; /* * 这里使用xpath来定位待修改的元素和属性，需要jaxen的支持。 *示例中将students-gen.xml的第一个student元素的sn属性改为001，其子元素name内容改为jeff。 *XmlMod.java */public class XmlMod {        /*     * 1.使用File定位文件资源，并基于此获得Document实例     *SAXReader saxReader = new SAXReader();     *Document document = saxReader.read(inputXml);     *2.Document实例的selectNodes方法可以传入xpath，并返回一个List实例，基于此使用迭代器，完成特定的应用     *List list = document.selectNodes("//students/student/@sn");     */    public void modifyDocument(File inputXml) {       try {           SAXReader saxReader = new SAXReader();           Document document = saxReader.read(inputXml);                      List list = document.selectNodes("//students/student/@sn");           Iterator iter = list.iterator();           while (iter.hasNext()) {              Attribute attribute = (Attribute) iter.next();              if (attribute.getValue().equals("01"))                  attribute.setValue("001");           }           list = document.selectNodes("//students/student");           iter = list.iterator();           while (iter.hasNext()) {              Element element = (Element) iter.next();              Iterator iterator = element.elementIterator("name");              while (iterator.hasNext()) {                  Element nameElement = (Element) iterator.next();                  if (nameElement.getText().equals("sam"))                     nameElement.setText("jeff");              }           }           XMLWriter output = new XMLWriter(new FileWriter(new File(                  "students-modified.xml")));           output.write(document);           output.close();       }        catch (DocumentException e) {           System.out.println(e.getMessage());       } catch (IOException e) {           System.out.println(e.getMessage());       }    }     /*     * selectSingleNode如果有多个只取第一个     */    public void modifyDocument2(File inputXml){        SAXReader saxReader = new SAXReader();        try {            Document document = saxReader.read(inputXml);            Node nodeAttr=document.selectSingleNode("//students/student/@sn");            System.out.println(nodeAttr.getText());            nodeAttr.setText("nodeAttr");                        Node nodeEle=document.selectSingleNode("//students/student");            System.out.println(nodeEle.getText());            nodeEle.setText("nodeEle");                               XMLWriter output = new XMLWriter(new FileWriter(new File(                       "students-modified2.xml")));                output.write(document);                            output.close();                } catch (Exception e) {            e.printStackTrace();        }                    }                    public static void main(String[] argv) {       XmlMod dom4jParser = new XmlMod();       //dom4jParser.modifyDocument(new File("students-gen.xml"));       dom4jParser. modifyDocument2(new File("students-gen.xml"));    }}

 

生成students-modified.xml

<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="students.xsl"?><students>  <!--An Student Catalog-->    <student sn="001">    <name>jeff</name>    <age>18</age>  </student>  <student sn="02">    <name>lin</name>    <age>20</age>  </student></students>

生成students-modified2.xml

<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="students.xsl"?><students>  <!--An Student Catalog-->    <student sn="nodeAttr"><name>sam</name><age>18</age>nodeEle</student>  <student sn="02">    <name>lin</name>    <age>20</age>  </student></students>

 

1.使用File定位文件资源，并基于此获得Document实例

SAXReader saxReader = new SAXReader();

Document document = saxReader.read(inputXml);

2.Document实例的selectNodes方法可以传入xpath，并返回一个List实例，基于此使用迭代器，完成特定的应用

List list = document.selectNodes("//students/student/@sn");

 

3.遍历XML文档

这里提供两种遍历方法，一种是基于迭代的遍历，一种是基于Visitor模式的遍历。这里介绍迭代的

 

package lqy.Dom4jTest;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;/* * 方法traversalDocumentByIterator()提供一种基于迭代的遍历实现，每个Element通过elementIterator()和attributeIterator()取代其子元素和属性的迭代器。 */public class XmlIterator {    private File inputXml;        public XmlIterator(File inputXml) {       this.inputXml = inputXml;    }    public static void main(String[] argv) {        XmlIterator dom4jParser = new XmlIterator(new File("students-gen.xml"));        dom4jParser.traversalDocumentByIterator();     }                public Element getRootElement() {        return getDocument().getRootElement();     }        public Document getDocument() {        SAXReader saxReader = new SAXReader();        Document document = null;        try {            document = saxReader.read(inputXml);        } catch (Exception e) {            e.printStackTrace();        }        return document;     }        /*     * 该方法只是枚举了两层，如果一直挖的话要用递归方法     */    public void traversalDocumentByIterator() {        Element root = getRootElement();        // 枚举根节点下所有子节点        for (Iterator ie = root.elementIterator(); ie.hasNext();) {            System.out.println("======");            Element element = (Element) ie.next();            System.out.println(element.getName());              // 枚举属性            for (Iterator ia = element.attributeIterator(); ia.hasNext();) {               Attribute attribute = (Attribute) ia.next();               System.out.println(attribute.getName() + ":"                      + attribute.getData());            }                        // 枚举当前节点下所有子节点            for (Iterator ieson = element.elementIterator(); ieson.hasNext();) {               Element elementSon = (Element) ieson.next();               System.out.println(elementSon.getName() + ":"+ elementSon.getText());            }        }     }                }

输出

 

4.通过Element找到节点

package lqy.Dom4jTest;import java.io.File;import java.util.Iterator;import java.util.List;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.Element;import org.dom4j.Node;import org.dom4j.io.SAXReader;public class XmlReadByElement {    /**     * @param args     * @throws Exception      */    public static void main(String[] args) throws Exception {        XmlReadByElement.getOneEle();        XmlReadByElement.getEles();        XmlReadByElement.getAttrs();        XmlReadByElement.getOneAttr();    }            public static Document getDocument() throws Exception{        SAXReader reader = new SAXReader();        Document  document = reader.read(new File("students-read.xml"));        return document;    }        //要顺序一个一个往下找    public static void getOneEle() throws Exception{        Document  document=getDocument();        Element rootElm = document.getRootElement();        Element e=rootElm.element("lqy");        System.out.println("arrt:"+e.attributeValue("aa"));        Element e2=e.element("login");        System.out.println("text:"+e2.getText());                    }        public static void getEles() throws Exception{        Document  document=getDocument();        Element rootElm = document.getRootElement();        List eList=rootElm.elements("student");        Iterator it=eList.iterator();        while(it.hasNext()){            Element elm=(Element)it.next();            System.out.println("arrt:"+elm.attributeValue("sn"));        }    }            public static void getOneAttr() throws Exception{        Document  document=getDocument();        Node node1=document.selectSingleNode("//students/lqy/login");        Element elm=(Element)node1;        System.out.println("attr:"+elm.attributeValue("sn"));            }        public static void getAttrs() throws Exception{        Document  document=getDocument();        List list = document.selectNodes("//students/student");        Iterator it=list.iterator();        while(it.hasNext()){            Element elm=(Element)it.next();            System.out.println("attr:"+elm.attributeValue("sn"));        }    }   }

 

students-read.xml

<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="students.xsl"?><students>  <!--An Student Catalog-->  <student sn="01">    <name>sam</name>    <age>18</age>  </student>  <student sn="02">    <name>lin</name>    <age>20</age>  </student>    <lqy aa="123123123">    <login sn="03">luo</login>    <pass>123456</pass>  </lqy></students>

输出结果

 

5.通过XPath找到节点

package lqy.Dom4jTest;import java.io.File;import java.util.Iterator;import java.util.List;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.Element;import org.dom4j.Node;import org.dom4j.io.SAXReader;public class XmlReadByXPath {    /**     * @param args     * @throws Exception      */    public static void main(String[] args) throws Exception {        XmlReadByXPath.getOneEleByXPath();        XmlReadByXPath.getElesByXPath();        XmlReadByXPath.getAttrsByXPath();        XmlReadByXPath.getOneAttrByXPath();    }            public static Document getDocument() throws Exception{        SAXReader reader = new SAXReader();        Document  document = reader.read(new File("students-read.xml"));        return document;    }        public static void getOneEleByXPath() throws Exception{        Document  document=getDocument();        Node node1=document.selectSingleNode("//students/lqy/login");        String nodeText1=node1.getText();        System.out.println("nodeText1："+nodeText1);                //假如多个只返回第一个        Node node2=document.selectSingleNode("//students/student/name");        String nodeText2=node2.getText();        System.out.println("nodeText2："+nodeText2);                Node node3=document.selectSingleNode("//students/student/@sn");        short nodeText3=node1.ATTRIBUTE_NODE;        System.out.println("nodeText3："+nodeText3);            }        public static void getElesByXPath() throws Exception{        Document  document=getDocument();        List list = document.selectNodes("//students/student/name");        Iterator it=list.iterator();        while(it.hasNext()){            Element elm=(Element)it.next();             System.out.println("elm:"+elm.getText());        }    }            public static void getOneAttrByXPath() throws Exception{        Document  document=getDocument();        Node node1=document.selectSingleNode("//students/lqy/login");        Element elm=(Element)node1;        System.out.println("attr:"+elm.attributeValue("sn"));            }        public static void getAttrsByXPath() throws Exception{        Document  document=getDocument();        List list = document.selectNodes("//students/student");        Iterator it=list.iterator();        while(it.hasNext()){            Element elm=(Element)it.next();            System.out.println("attr:"+elm.attributeValue("sn"));        }    }        }

输出结果

 

6.XML转换成String

package lqy.Dom4jTest;import java.io.File;import java.util.Iterator;import java.util.List;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.Element;import org.dom4j.Node;import org.dom4j.io.SAXReader;public class XMLToString {    /**     * @param args     * @throws Exception      */    public static void main(String[] args) throws Exception {        SAXReader reader = new SAXReader();        Document  document = reader.read(new File("students-read.xml"));                String docXmlText=document.asXML();        System.out.println(docXmlText);        System.out.println("------------------docXmlText-------------------");        Element root=document.getRootElement();           String rootXmlText=root.asXML();        System.out.println(rootXmlText);        System.out.println("------------------rootXmlText-------------------");        Element memberElm=root.element("lqy");        String memberXmlText=memberElm.asXML();        System.out.println(memberXmlText);        System.out.println("------------------memberXmlText-------------------");    }        }

 

 输出

  

 

参考

1.http://zhangjunhd.blog.51cto.com/113473/126310

2.http://www.blogjava.net/junglesong/archive/2008/02/21/181196.html