JSP账号密码验证提示

u></p><p><b>exception</b> <pre>org.apache.jasper.JasperException: An exception occurred processing JSP page /process/check.jsp at line 28

25: 		response.sendRedirect(&quot;../index.jsp&quot;);
26: 	}else{
27: 		Dao dao = new Dao();//用户验证
28: 		int result = dao.checkForm(loginUser.toString(), pwd);//从数据库里查询此用户
29: 		if (1==result) {
30: 			response.addHeader(&quot;success&quot;, &quot;true&quot;);			//登陆成功标记
31: 			session.setAttribute(&quot;loginUser&quot;, loginUser);//验证是否为用户


Stacktrace:
	org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
</pre></p><p><b>root cause</b> <pre>java.lang.NullPointerException
	com.tonetime.dao.Dao.checkForm(Dao.java:288)
	org.apache.jsp.process.check_jsp._jspService(check_jsp.java:84)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
</pre></p><p><b>note</b> <u>The full stack trace of the root cause is available in the Apache Tomcat/6.0.29 logs.</u></p><HR size="1" noshade="noshade"><h3>Apache Tomcat/6.0.29</h3></body></html>

应该是Dao类的验证表单函数没写好，导致空指针异常,

原本思路是 根据输入的loginUser和pwd 到数据库查询。

但是如果这两个参数都不存在的话势必会返回null;