我按照录像全都配置完了 可以进入主界面 但是进入后台的时候输入用户名和密码之后无法进入后台 数据库无法连接

这是IE中显示的内容
HTTP Status 500 - 

--------------------------------------------------------------------------------

type Exception report

message 

description The server encountered an internal error () that prevented it from fulfilling this request.

exception 

javax.servlet.ServletException: java.lang.NullPointerException
org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:516)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:423)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:226)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:415)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)


root cause 

java.lang.NullPointerException
com.wgh.core.ConnDB.executeQuery(ConnDB.java:58)
com.wgh.dao.ManagerDAO.checkManager(ManagerDAO.java:15)
com.wgh.action.Manager.managerLogin(Manager.java:44)
com.wgh.action.Manager.execute(Manager.java:22)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:421)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:226)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:415)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)


note The full stack trace of the root cause is available in the Apache Tomcat/6.0.26 logs.


Tomcat中说是DbConnectionManager.getConnection()获得数据连接失败