Dom4j的简单使用

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要使用dom4j读写XML文档,需要先下载dom4j包,dom4j官方网站在 http://www.dom4j.org/
目前最新dom4j包下载地址:http://nchc.dl.sourceforge.net/sourceforge/dom4j/dom4j-1.6.1.zip

解开后有两个包,仅操作XML文档的话把dom4j-1.6.1.jar加入工程就可以了,如果需要使用XPath的话还需要加入包jaxen-1.1-beta-7.jar.

以下是相关操作:

一.Document对象相关

1.读取XML文件,获得document对象.
SAXReader reader = new SAXReader();
Document document = reader.read(new File("input.xml"));

2.解析XML形式的文本,得到document对象.
            String text = "<members></members>";
            Document document = DocumentHelper.parseText(text);
3.主动创建document对象.
            Document document = DocumentHelper.createDocument();
            Element root = document.addElement("members");// 创建根节点
二.节点相关

1.获取文档的根节点.
Element rootElm = document.getRootElement();
2.取得root节点下子节点名字为member的节点.
Element memberElm=root.element("member");// "member"是节点名
3.取得节点的文字
String text=memberElm.getText();
也可以用:
String text=root.elementText("name");这个是取得根节点下的name字节点的文字.

4.取得某节点下名为"member"的所有子节点并进行遍历.
List nodes = rootElm.elements("member");

for (Iterator it = nodes.iterator(); it.hasNext();) {
   Element elm = (Element) it.next();
   // do something
}
5.对某节点下的所有子节点进行遍历.
            for(Iterator it=root.elementIterator();it.hasNext();){
                Element element = (Element) it.next();
                // do something
            }
6.在某节点下添加子节点.
Element ageElm = newMemberElm.addElement("age");
7.设置节点文字.
ageElm.setText("29");
8.删除某节点.
parentElm.remove(childElm);// childElm是待删除的节点,parentElm是其父节点
三.属性相关.
1.取得某节点下的某属性
            Element root=document.getRootElement();
            Attribute attribute=root.attribute("size");// 属性名name
2.取得属性的文字
            String text=attribute.getText();
也可以用:
String text2=root.element("name").attributeValue("firstname");这个是取得根节点下name字节点的属性firstname的值.

3.遍历某节点的所有属性
            Element root=document.getRootElement();
            for(Iterator it=root.attributeIterator();it.hasNext();){
                Attribute attribute = (Attribute) it.next();
                String text=attribute.getText();
                System.out.println(text);
            }
4.设置某节点的属性和文字.
newMemberElm.addAttribute("name", "sitinspring");
5.设置属性的文字
            Attribute attribute=root.attribute("name");
            attribute.setText("sitinspring");
6.删除某属性
            Attribute attribute=root.attribute("size");// 属性名name
            root.remove(attribute);
四.将文档写入XML文件.
1.文档中全为英文,不设置编码,直接写入的形式.
XMLWriter writer = new XMLWriter(new FileWriter("output.xml"));
writer.write(document);
writer.close();
2.文档中含有中文,设置编码格式写入的形式.
            OutputFormat format = OutputFormat.createPrettyPrint();
            format.setEncoding("GBK");    // 指定XML编码
            XMLWriter writer = new XMLWriter(new FileWriter("output.xml"),format);

            writer.write(document);
            writer.close();
五.字符串与XML的转换
1.将字符串转化为XML
String text = "<members> <member>sitinspring</member> </members>";
Document document = DocumentHelper.parseText(text);
2.将文档或节点的XML转化为字符串.
            SAXReader reader = new SAXReader();
            Document document = reader.read(new File("input.xml"));
            Element root=document.getRootElement();
            String docXmlText=document.asXML();
            String rootXmlText=root.asXML();
            Element memberElm=root.element("member");
            String memberXmlText=memberElm.asXML();
六.使用XPath快速找到节点.
读取的XML文档示例
<?xml version="1.0" encoding="UTF-8"?>
<projectDescription>
<name>MemberManagement</name>
<comment></comment>
<projects>
    <project>PRJ1</project>
    <project>PRJ2</project>
    <project>PRJ3</project>
    <project>PRJ4</project>
</projects>
<buildSpec>
    <buildCommand>
      <name>org.eclipse.jdt.core.javabuilder</name>
      <arguments>
      </arguments>
    </buildCommand>
</buildSpec>
<natures>
    <nature>org.eclipse.jdt.core.javanature</nature>
</natures>
</projectDescription>

使用XPath快速找到节点project.
public static void main(String[] args){
    SAXReader reader = new SAXReader();

    try{
      Document doc = reader.read(new File("sample.xml"));

      List projects=doc.selectNodes("/projectDescription/projects/project");

      Iterator it=projects.iterator();

      while(it.hasNext()){
        Element elm=(Element)it.next();
        System.out.println(elm.getText());
      }

    }
    catch(Exception ex){
       ex.printStackTrace();
    }

package com.ctrip.search.dom;import java.io.File;import java.io.InputStream;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import java.util.regex.Matcher;import java.util.regex.Pattern;import org.dom4j.Attribute;import org.dom4j.Document;import org.dom4j.Element;import org.dom4j.io.SAXReader;public class ElementDemo {public static void main(String[] args) throws Exception {Document doc = getDocument();        //testElementApi(doc);Element root = doc.getRootElement();StringBuilder result = printElement(root);System.out.println(result.toString());}public static Document getDocument() throws Exception{SAXReader reader = new SAXReader();//采用文件的方式读取文件//        File file = new File("D:/lqteng/Dom4jDemo/file/request.xml");//        Document doc = reader.read(file); //以类加载的路径为根路径，所以这个地方要写成绝对路径        InputStream in = ElementDemo.class.getResourceAsStream("/request.xml");        //这个是采用类加载器的方式读取，只要写出类加载器要加载的文件名称即可//        InputStream in2 = ElementDemo.class.getClassLoader().getResourceAsStream("request.xml");        Document doc = reader.read(in);                return doc;}public static void testElementApi(Document doc) throws Exception{        //获取这个文档的根元素        Element requestsNode = doc.getRootElement();        List<Element> requestNodes = new ArrayList<Element>();                if("Requests".equalsIgnoreCase(requestsNode.getName())){//         List<Element> subNodes = requestsNode.elements();//         for(Element sub : subNodes){//         if("Request".equalsIgnoreCase(sub.getName())){//                 requestNodes.add(sub); //         }//         }        Iterator<Element> subNodes = (Iterator<Element>)requestsNode.elementIterator();        for(;subNodes.hasNext();){        Element sub = subNodes.next();           if("Request".equalsIgnoreCase(sub.getName())){                   requestNodes.add(sub);         }        }        }else if("Request".equalsIgnoreCase(requestsNode.getName())){        requestNodes.add(requestsNode);        }                if(requestNodes != null && requestNodes.size() > 0){        Element firstRequest = requestNodes.get(0);        Element statNode = firstRequest.element("stat");            if(statNode.isTextOnly()){            System.out.println("statNode text:"+statNode.getTextTrim());            }else{            List<Element> statNodes = firstRequest.elements("query");            for(Element statE : statNodes){            System.out.println(statE.getName());            //如果没有子元素那么就为true            System.out.println(statE.isTextOnly());            }            }                        //打印出所有sort元素下的name和asc，如果为内容为公式则取出公式            //获取firstRequest元素下的sort元素，如果firstRequest元素下面有多个sort元素，那么就应该使用elements("sort")            Element sortE = firstRequest.element("sort");            //获取sortE元素的所有子元素            List<Element> sortSubEs = sortE.elements();            for(Element sortSubE : sortSubEs){            String name = sortSubE.getName();//            String asc = sortSubE.getTextTrim();            //获取sortE元素下的name元素的text            String asc = sortE.elementTextTrim(name);            Pattern pattern = Pattern.compile("\\$\\{(([a-z]|[A-Z]|\\.|\\s)+)\\}");            Matcher matcher = pattern.matcher(asc);            if(matcher.find()){            name = asc;            //获取sortSubE元素的order属性的值            asc = sortSubE.attributeValue("order");            }                System.out.println("name: "+ name +",asc: "+("desc".equalsIgnoreCase(asc) ? false : true));            }        }}public static StringBuilder printElement(Element e){if(e == null){return new StringBuilder("");}StringBuilder str = new StringBuilder();str.append("<"+e.getName());    Iterator attrIterator = e.attributeIterator();    for(;attrIterator.hasNext();){    Attribute attr = (Attribute)attrIterator.next();    str.append(" "+attr.getName()+"='"+ attr.getValue() +"'");    }    str.append(">");        if(e.isTextOnly()){    str.append(e.getText());    }else{    List<Element> subs = e.elements();    for(Element sub : subs){    str.append("\n");    str.append(printElement(sub));    }    str.append("\n");    }    str.append("</"+ e.getName() +">");return str;}}

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