访问不存在页面404异常处理

web.xml

<error-page>
  <error-code>404</error-code>
  <location>/3GShop/index.jsp</location>
</error-page>
<error-page>
  <exception-type>java.lang.Throwable</exception-type>
  <location>/3GShop/index.jsp</location>
</error-page>