dom4j中处理XML命名空间的问题，哪位指点下，谢谢！！！

<?xml version="1.0" encoding="UTF-8"?>
<MyXML xmlns="http://www.ttt.com/ttt-TrdInfo-1-0" xmlns:x="http://www.ttt.com/ttt/metadata.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="res286.xsd">
<Hdr ReqId="001" Tid="1002" Cid="500" user="cuishen" Mname="supermarket" pwd="543200210"/>
<Car Flg="T" Cod="ccc" Door="kkk" mktId="b01">
<Key KeyID="t01"/>
</Car>
</MyXML>

import java.io.File;
import java.util.List;
import java.util.Map;
import java.util.HashMap;

import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.XPath;
import org.dom4j.Attribute;
import org.dom4j.io.SAXReader;
import org.dom4j.DocumentException;

public class ReadMyXML{
public static void main(String args[]){
File xmlFile = new File("c:/myXML.xml");
SAXReader xmlReader = new SAXReader();
try{
Document document = xmlReader.read(xmlFile);

/*测试代码1
Attribute valueAttribute = (Attribute)document.selectSingleNode("//MyXML/Hdr/@ReqId");
System.out.println(valueAttribute.getText());
*/

///*测试代码2    xml的命名空间问题
HashMap xmlMap = new HashMap();
xmlMap.put("mo","http://www.ttt.com/ttt-TrdInfo-1-0");
xmlMap.put("x","http://www.ttt.com/ttt/metadata.xsd");
xmlMap.put("xsi","http://www.w3.org/2001/XMLSchema-instance");
XPath x = document.createXPath("//mo:MyXML/Hdr/@ReqId");
x.setNamespaceURIs(xmlMap);
Attribute valueAttribute = (Attribute)x.selectSingleNode(document);
System.out.println(valueAttribute.getText());
//*/
}catch(DocumentException e){
e.printStackTrace();
}
}
}