dom4j 使用xpath 解析 persistence.xml 出现xmlns后不能解析问题解决

xml文件为：

    <?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" >
  <persistence-unit name="jdztjxPU" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <class>db.TUser</class>
    <class>db.TDept</class>
    <properties>
      <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>

      <property name="hibernate.connection.username" value="root"/>
      <property name="hibernate.connection.password" value="root"/>
      <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/jdztjx?useUnicode=true&amp;characterEncoding=UTF-8"/>
     
      <property name="hibernate.cache.provider_class" value="org.hibernate.cache.NoCacheProvider"/>
    </properties>
  </persistence-unit>
</persistence>

最终解析代码为：

    try {
            String fp = "persistence.xml";//此处为相对路径
            Map map = new HashMap();
            map.put("persistence", "http://java.sun.com/xml/ns/persistence");//将persistence注册为namesapce的名称
            SAXReader saxReader = new SAXReader();
            File file = new File(fp);
            System.out.println(file.getAbsolutePath());
            saxReader.getDocumentFactory().setXPathNamespaceURIs(map);
            Document document = saxReader.read(file);
            String xpathUser="//persistence:persistence/persistence:persistence-unit[@name='"+PersistenceCollectUnitName+"']/persistence:properties/persistence:property[@name='hibernate.connection.username']";//书写xpath时使用 persistence
            List <Element> persisList = document.selectNodes(xpathUser);
            //System.out.println(persisList.size());
            Element elUser=persisList.get(0);
            user=elUser.attributeValue("value");

             //...省略一点
                      }catch(DocumentException ex){
            Logger.getLogger(DbConn.class.getName()).log(Level.SEVERE, null, ex);
        }