dom4j-1.6.1.jar

jaxen-1.1-beta-6.jar（XPath必备）

取某一节点

Element root = (Element) document.selectSingleNode("//root");

取某一节点的属性

Attribute attribute = (Attribute) document.selectSingleNode("//root/cell/@value");

使用经验

我们在做系统间交互时，通常通过自定义的xml文件进行数据交换。例如：系统A需要向系统B传输一个xml字串的条件如下：

<?xml version="1.0" encoding="gb2312"?> <root systemid="Darenkou" userid="admin" default="DA" icon="0000">        <cell value=""/> </root>

系统A只需填充cell节点的value属性值，我的建议是将这段xml写成本地文件，每次传输时首先读取xml文件，再置cell节点的value属性值，然后将xml对象转变成字串传给系统B。这样的优点是：一般systemid="Darenkou" userid="admin" default="DA" icon="0000" 是传输参数，当有所变动时只需修改本地文件即可。

详细例程

test.xml

<?xml version="1.0" encoding="gb2312"?> <root id="TK12" name="管理员" value=""/>

XmlTest.java

import java.io.File; import java.io.IOException; import java.io.StringWriter; import java.io.UnsupportedEncodingException; import java.util.HashMap; import java.util.Iterator;   import org.dom4j.Document; import org.dom4j.DocumentException; import org.dom4j.Element; import org.dom4j.io.OutputFormat; import org.dom4j.io.SAXReader; import org.dom4j.io.XMLWriter;   public class XmlTest {        public static String generateXml(HashMap map) {               String strXml = null;                 if (map != null) {                        SAXReader reader = new SAXReader();                      Document document = null;                        try {                             document = reader.read(new File("D:/test.xml"));                      } catch (DocumentException e) {                             e.printStackTrace();                        }                        Element root = (Element) document.selectSingleNode("//root");                      root.attribute("value").setValue("分布");                        Iterator iter = map.keySet().iterator();                      while (iter.hasNext()) {                             String key = (String) iter.next();                             String value = (String) map.get(key);                               Element element = root.addElement("cell").addAttribute("value",                                           key);                             element.addElement("element").addAttribute("type", "数值")                                           .addAttribute("name", "人数").addText(value);                        }                        strXml = encodeXml(document, "gb2312");               }                 return strXml;        }          private static String encodeXml(Document document, String aEncode) {               // 进行编码转换               StringWriter sw = new StringWriter();                 OutputFormat format = OutputFormat.createPrettyPrint();               format.setEncoding(aEncode);                 try {                      XMLWriter writer = new XMLWriter(format);                      writer.setWriter(sw);                      writer.write(document);               } catch (UnsupportedEncodingException e) {                      e.printStackTrace();               } catch (IOException e) {                      e.printStackTrace();               }                 return sw.toString();        }          public static void main(String[] args) {               HashMap map = new HashMap();               map.put("上海", "200");               map.put("北京", "300");               map.put("天津", "300");                 System.out.println(generateXml(map));          } }