jsp连接出错，请帮忙分析下

Question

HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage 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:523)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:421)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
root cause java.lang.NullPointerException
com.core.ConnDB.executeQuery(ConnDB.java:53)
com.dao.ManagerDAO.checkManager(ManagerDAO.java:73)
com.action.Manager.managerLogin(Manager.java:51)
com.action.Manager.execute(Manager.java:24)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
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/6.0.18 logs.
--------------------------------------------------------------------------------Apache Tomcat/6.0.18

Answer 1

ConnDB的53出现空指针，请检查ConnDB的executeQuery方法以及ManagerDAO的73调用该方法处传递参数是否有问题

Answer 2

root cause java.lang.NullPointerException 
com.core.ConnDB.executeQuery(ConnDB.java:53) 做开发最重要的就是学会看错误
楼主可以看root cause就可以看出个大概了

Answer 3

com.core.ConnDB.executeQuery(ConnDB.java:53);
从这一句就知道，查询的时候出错，也就是sql 语句写错了, 

Answer 4

空指针错误的，你可以在百度或google一下

Answer 5

在查询分析器看看sql语句对不对