这是web.xml:<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd"> <web-app> <display-name>WebModule1</display-name> <servlet> <servlet-name>check</servlet-name> <servlet-class>misoa.check</servlet-class> </servlet> <servlet> <servlet-name>debugjsp</servlet-name> <description>Added by JBuilder to compile JSPs with debug info</description> <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class> <init-param> <param-name>classdebuginfo</param-name> <param-value>true</param-value> </init-param> <load-on-startup>3</load-on-startup> </servlet> <servlet-mapping> <servlet-name>check</servlet-name> <url-pattern>/check</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>debugjsp</servlet-name> <url-pattern>*.jsp</url-pattern> </servlet-mapping> </web-app>
String sql="select from 'table' where Id='UserInfor.getId' and Password='UserInfor.getPassowrd'"; 放到数据库查询分析器中试试,有问题,
select from 'table' where Id='UserInfor.getId' and Password='UserInfor.getPassowrd' 应该是 select * from 'table' where Id='UserInfor.getId' and Password='UserInfor.getPassowrd' 你的查询语句少个*,当然什么也查不出来,出现空指针异常也正常
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<display-name>WebModule1</display-name>
<servlet>
<servlet-name>check</servlet-name>
<servlet-class>misoa.check</servlet-class>
</servlet>
<servlet>
<servlet-name>debugjsp</servlet-name>
<description>Added by JBuilder to compile JSPs with debug info</description>
<servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
<init-param>
<param-name>classdebuginfo</param-name>
<param-value>true</param-value>
</init-param>
<load-on-startup>3</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>check</servlet-name>
<url-pattern>/check</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>debugjsp</servlet-name>
<url-pattern>*.jsp</url-pattern>
</servlet-mapping>
</web-app>
放到数据库查询分析器中试试,有问题,
应该是
select * from 'table' where Id='UserInfor.getId' and Password='UserInfor.getPassowrd'
你的查询语句少个*,当然什么也查不出来,出现空指针异常也正常
private LoginUserInfo UserInfo;
这个LoginUserInfo只申明了一个对象,并没有初始化
就直接UserInfo.setId(request.getParameter("id"));
肯定报NullPointerException
new 一个LoginUserInfo应该就没问题了
select * from 'table' where Id='UserInfor.getId()' and Password='UserInfor.getPassowrd()'
getId()和getPassword()是方法不是属性
在check.java用LoginUserInfo的话必须先初始化才可以用,即用request.getParameter("id")和request.getParameter("password")等进行初始化,然后才可以用,这和struts、spring等是不同的。