hibernate映射实体类查询时数据库空字段赋值给实体类报错的问题

org.hibernate.InvalidMappingException: Could not parse mapping document from resource cn/pojo/EmpDao.xml
    at org.hibernate.cfg.Configuration.addResource(Configuration.java:616)
    at org.hibernate.cfg.Configuration.parseMappingElement(Configuration.java:1635)
    at org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:1603)
    at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1582)
    at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1556)
    at org.hibernate.cfg.Configuration.configure(Configuration.java:1476)
    at org.hibernate.cfg.Configuration.configure(Configuration.java:1462)
    at cn.tool.HibernateUtil.<clinit>(HibernateUtil.java:16)
    at cn.service.EmpService.findEmpById(EmpService.java:16)
    at cn.Test.main(Test.java:9)
Caused by: org.hibernate.InvalidMappingException: Could not parse mapping document from input stream
    at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:555)
    at org.hibernate.cfg.Configuration.addResource(Configuration.java:613)
    ... 9 more
Caused by: org.dom4j.DocumentException: Connection reset Nested exception: Connection reset
    at org.dom4j.io.SAXReader.read(SAXReader.java:484)
    at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:546)
    ... 10 more
Exception in thread "main" java.lang.NullPointerException
    at cn.tool.HibernateUtil.currentSession(HibernateUtil.java:29)
    at cn.service.EmpService.findEmpById(EmpService.java:16)
    at cn.Test.main(Test.java:9)

 public void setComm(Object comm) {
        if(comm!=null)
            this.comm = (double)comm;
    }