<root>

    <flw>

    <name>aa</name>

    <age>22</age>

    <instance_info>

          <num>1</num>

           <code>0</code>

          <instance>

               <ip>10.1.1.2</ip>

               <mask>9999</mask>

         </instance>

         <instance>

               <ip>10.1.1.5</ip>

               <mask>717</mask>

         </instance>

    </instance_info>

    <instance_info>

          <num>2</num>

           <code>33</code>

          <instance>

               <ip>10.1.1.2</ip>

               <mask>9999</mask>

         </instance>

         <instance>

               <ip>10.1.1.9</ip>

               <mask>878</mask>

         </instance>

    </instance_info>

   </flw>

</root>

import java.io.ByteArrayInputStream;

import java.io.UnsupportedEncodingException;

import java.util.Iterator;

import org.dom4j.DocumentException;

import org.dom4j.io.SAXReader;

public class XMLParser {

       public static void main(String[] args) {

            String xml = "<root><flw><name>aa</name><age>22</age><instance_info><num>1</num><code>0</code><instance><ip>10.1.1.2</ip><mask>9999</mask></instance><instance><ip>10.1.1.5</ip><mask>717</mask></instance></instance_info><instance_info><num>2</num><code>33</code><instance><ip>10.1.1.2</ip><mask>9999</mask></instance><instance><ip>10.1.1.9</ip><mask>878</mask></instance></instance_info></flw></root>";

            long start = System.currentTimeMillis();

            SAXReader reader = new SAXReader();

            try {

                org.dom4j.Document doc = reader.read(new ByteArrayInputStream(xml

                        .getBytes("UTF-8")));

                org.dom4j.Element root = doc.getRootElement();

                org.dom4j.Element element;

                org.dom4j.Element element2;

                org.dom4j.Element element3;

                for (Iterator i = root.elementIterator("flw"); i.hasNext();) {

                    element = (org.dom4j.Element) i.next();

                    System.out

                            .println("name:[" + element.elementText("name") + "]");

                    System.out.println("age:[" + element.elementText("age") + "]");

                    for (Iterator j = element.elementIterator("instance_info"); j

                            .hasNext();) {

                        element2 = (org.dom4j.Element) j.next();

                        System.out.println("\tnum:[" + element2.elementText("num")

                                + "]");

                        System.out.println("\tcode:["

                                + element2.elementText("code") + "]");

                        for (Iterator k = element2.elementIterator("instance"); k

                                .hasNext();) {

                            element3 = (org.dom4j.Element) k.next();

                            System.out.println("\t\tip:["

                                    + element3.elementText("ip") + "]");

                            System.out.println("\t\tmask:["

                                    + element3.elementText("mask") + "]");

                        }

                    }

                }

            } catch (DocumentException e) {

                e.printStackTrace();

            } catch (UnsupportedEncodingException e) {

                e.printStackTrace();

            }

            long end = System.currentTimeMillis();

            System.out.println("耗时：" + (end - start) + "ms");

        }

}