求高手给解决方案 j2ee数据库连接问题 帮帮忙!

Question

小女子刚开始做j2ee项目，测试上线遇到奇怪的问题： 系统一直运行正常，突然报若干空指针的错误，然后系统就崩溃了，任何访问数据库的页面都不能访问。 
检查日志发现所有数据库连接不能创建并报java.lang.NullPointerException。但是重启server后又能正常运行一天。 烦请各位高人指点？不胜感激，有分奉送

Answer 1

关的，每次open一个connect都会有close
所以觉得奇怪

Answer 2

我也有
java.lang.ClassNotFoundException: com.microsoft.jdbc.sqlserver.SQLServerDriver
关注！

Answer 3

本人一直是用jtds驱动~满好的!~没出现过什么问题~

Answer 4

非常感谢大家，但是我还是不能确定是不是数据库连接满 在数据库里可以监控到吗？或者在连接池里监控？我先把一部门报错贴一下：
E SRVE0026E: ［Servlet 错误］－［］：java.lang.NullPointerException
at cmswg.DBConnect.<init>(DBConnect.java(Compiled Code))
at org.apache.jsp._logonConfirm._jspService(_logonConfirm.java:129)
at com.ibm.ws.webcontainer.jsp.runtime.HttpJspBase.service(HttpJspBase.java(CompiledCode))
at javax.servlet.http.HttpServlet.service(HttpServlet.java(Compiled Code))
at com.ibm.ws.webcontainer.jsp.servlet.JspServlet$JspServletWrapper.service(JspServlet.java(Compiled Code))
at com.ibm.ws.webcontainer.jsp.servlet.JspServlet.serviceJspFile(JspServlet.java(Compiled Code))
at com.ibm.ws.webcontainer.jsp.servlet.JspServlet.service(JspServlet.java(Compiled Code))
at javax.servlet.http.HttpServlet.service(HttpServlet.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.StrictServletInstance.doService(StrictServletInstance.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet._service(StrictLifecycleServlet.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServicingServletState.service(StrictLifecycleServlet.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet.service(StrictLifecycleServlet.java(Inlined Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServletInstance.service(ServletInstance.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ValidServletReferenceState.dispatch(ValidServletReferenceState.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServletInstanceReference.dispatch(ServletInstanceReference.java(Inlined Compiled Code))
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.handleWebAppDispatch(WebAppRequestDispatcher.java(Compiled Code))
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.dispatch(WebAppRequestDispatcher.java(Compiled Code))
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.forward(WebAppRequestDispatcher.java(Compiled Code))
at com.ibm.ws.webcontainer.srt.WebAppInvoker.doForward(WebAppInvoker.java(Compiled Code))
at com.ibm.ws.webcontainer.srt.WebAppInvoker.handleInvocationHook(WebAppInvoker.java(Compiled Code))
at com.ibm.ws.webcontainer.cache.invocation.CachedInvocation.handleInvocation(CachedInvocation.java(Compiled Code))
at com.ibm.ws.webcontainer.cache.invocation.CacheableInvocationContext.invoke(CacheableInvocationContext.java(Compiled Code))
at com.ibm.ws.webcontainer.srp.ServletRequestProcessor.dispatchByURI(ServletRequestProcessor.java(Compiled Code))
at com.ibm.ws.webcontainer.oselistener.OSEListenerDispatcher.service(OSEListener.java(Compiled Code))
at com.ibm.ws.webcontainer.http.HttpConnection.handleRequest(HttpConnection.java(Compiled Code))
at com.ibm.ws.http.HttpConnection.readAndHandleRequest(HttpConnection.java(Compiled Code))
at com.ibm.ws.http.HttpConnection.run(HttpConnection.java(Compiled Code))
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java(Compiled Code))