Send request to put the page

<! - employees need to distinguish between modified or added; -> 
<TH form: Action = "@ {/} EMP" Method = "POST"> 
   <- - sending a request to modify the employee data put!> 
   <! - - 
   . 1, SPRINGMVC configuration HiddenHttpMethodFilter; (SpringBoot automatically configured) 
   2, form page to create a post 
   3, to create an input entry, name = "_ method"; the value that we specify the request method 
   -> 
   <input type = " hidden "name =" _ method " value =" put "th: if =" $ {emp = null!} "/>