【急】请教，Struts实例运行出错~~万分感谢！！！

Question

我实在找不到怎样解决这个问题了啊！请大家帮我解决一下吧。谢谢。来过的一定要留言哦。呵呵~万分感谢！！！HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception javax.servlet.ServletException
org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:545)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:486)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.mmxbb.exam.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:56)
root cause java.lang.NullPointerException
org.mmxbb.exam.dao.ExamineeDAO.isUser(ExamineeDAO.java:685)
org.mmxbb.exam.business.LogonAction.execute(LogonAction.java:26)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.mmxbb.exam.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:56)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.9 logs.
--------------------------------------------------------------------------------Apache Tomcat/5.5.9

Answer 1

org.mmxbb.exam.dao.ExamineeDAO.isUser(ExamineeDAO.java:685) 看看这个地方吧  空指针异常， 估计什么参数没有传递过去？  或者没有从数据库读出来？

Answer 2

空指针!
org.mmxbb.exam.dao.ExamineeDAO.isUser(ExamineeDAO.java:685) 
org.mmxbb.exam.business.LogonAction.execute(LogonAction.java:26) 
看这2句,在ExamineeDAO.java的685行和LogonAction的26行出现空指针

Answer 3

出现空指针啊  就是没有连上数据库吗
那myeclipse怎么连接Mysql数据库呢
不就是把WebRoot\WEB-INF\lib目录下的mysql-connector-java-3.0.16-ga-bin.jar类包文件到Tomcat安装目录的common\lib下吗
还要做些什么吗？谢谢各位高手了啊！呵呵

Answer 4

信息: Initializing, config='org.apache.struts.taglib.html.LocalStrings', returnNull=true
getConnection error: org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
2008-5-9 19:03:32 org.apache.struts.action.RequestProcessor processException
警告: Unhandled Exception thrown: class java.lang.NullPointerException
2008-5-9 19:03:32 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet action threw exception
java.lang.NullPointerException
at org.mmxbb.exam.dao.ExamineeDAO.isUser(ExamineeDAO.java:685)
at org.mmxbb.exam.business.LogonAction.execute(LogonAction.java:26)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.mmxbb.exam.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:56)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)
2008-5-9 19:03:48 org.apache.coyote.http11.Http11Protocol pause
信息: Pausing Coyote HTTP/1.1 on http-8080
2008-5-9 19:03:50 org.apache.catalina.core.StandardService stop
信息: Stopping service Catalina
2008-5-9 19:03:50 org.apache.coyote.http11.Http11Protocol destroy
信息: Stopping Coyote HTTP/1.1 on http-8080
这是调出来的错误

Answer 5

Cannot create JDBC driver of class '' for connect URL 

Answer 6

ExamineeDAO.java:685
处，空指针异常
看看这里怎么了