Spring中SimpleFormController各函数执行过程
显示表单
(1).handleRequest(HttpServletRequest request, HttpServletResponse response)
(2).handleRequestInternal(HttpServletRequest request,HttpServletResponse response)
(3).formBackingObject()
(4).initBinder()
?可选：onBindOnNewForm(HttpServletRequest, Object, BindException)
(5).showForm()
(6).referenceData()
处理标单
(1).handleRequest(HttpServletRequest request, HttpServletResponse response)
(2).handleRequestInternal(HttpServletRequest request,HttpServletResponse response)
(3).formBackingObject()
(4).onBind(HttpServletRequest, Object, Errors)
(5).绑定数据
(6).onBindAndValidate()
(7).processFormSubmission()
校验无错
(8).onSubmit
(9).doSubmitAction
校验有错
(8).showForm
