联接数据库的问题~~在线~看错误~

[pengpengpeng88]

Error: 500
Location: /testJDBC.jsp
Internal Servlet Error:

javax.servlet.ServletException
at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:384)
at _0002ftestJDBC_0002ejsp_0002ftestJDBC_jsp_0._jspService(Compiled Code)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:126)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:865)
at org.apache.jasper.runtime.JspServlet$JspServletWrapper.service(JspServlet.java:172)
at org.apache.jasper.runtime.JspServlet.serviceJspFile(JspServlet.java:259)
at org.apache.jasper.runtime.JspServlet.service(Compiled Code)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:865)
at org.apache.tomcat.core.ServletWrapper.handleRequest(Compiled Code)
at org.apache.tomcat.core.ContextManager.service(ContextManager.java:523)
at org.apache.tomcat.service.http.HttpConnectionHandler.processConnection(HttpConnectionHandler.java:146)
at org.apache.tomcat.service.TcpConnectionThread.run(SimpleTcpEndpoint.java:334)
at java.lang.Thread.run(Thread.java:466)

Root cause:
java.lang.NullPointerException
at _0002ftestJDBC_0002ejsp_0002ftestJDBC_jsp_0._jspService(Compiled Code)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:126)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:865)
at org.apache.jasper.runtime.JspServlet$JspServletWrapper.service(JspServlet.java:172)
at org.apache.jasper.runtime.JspServlet.serviceJspFile(JspServlet.java:259)
at org.apache.jasper.runtime.JspServlet.service(Compiled Code)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:865)
at org.apache.tomcat.core.ServletWrapper.handleRequest(Compiled Code)
at org.apache.tomcat.core.ContextManager.service(ContextManager.java:523)
at org.apache.tomcat.service.http.HttpConnectionHandler.processConnection(HttpConnectionHandler.java:146)
at org.apache.tomcat.service.TcpConnectionThread.run(SimpleTcpEndpoint.java:334)
at java.lang.Thread.run(Thread.java:466)

什么错误~

[polyhill]

空指针错误，你仔细查查你的jsp代码吧！

[zez]

是空指针错误,不是数据库错误
看看你是不是对一个空对象进行操作了?

[freeever]

一般空指针错误是调用了仍为null的对象的方法；
例如：
Vector aaa;
其间没有初始化或赋值，然后直接调用
aaa.elementAt(i)

[旋转的魔方]

可能是你程序里面的某个变量没有初始化，或者得到的结果集是null,你要处理这些情况。

[pengpengpeng88]

thank you ~