Supplementary annotation knowledge

@ModelAttribute

This annotation precedes the parameter, so you can put the value of the parameter directly into the session, create a key-value pair, and give the key itself, so @modelAttribute (” key “) is the parameter value

(uncommon) This annotation precedes methods that do not request processing, and also registers values in the session as key:value, divided into methods that return a value and methods that do not return a value. The difference is that methods with no return value require an explicit addition of the object to the model.

More than one line model. The addAttribute (" key ", "value")

@modelAttribute (“value”) this annotation if it has a value in it, it’s going to put that value in it. You want parameters, for example @modelattribute (” myApp “)

I returned a user object named user, and the foreground fetched the object and asked ${myapp.user. Properties inside the object}

@RequestMapping("/login")
	public String login(@ModelAttribute("user") String user, @ModelAttribute("pwd") String pwd) {
		System.out.println(user);
		System.out.println(pwd);
		return "hello";
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The value on the front interface can be expressed as EL

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"% > <! DOCTYPE html> <html> <head> <meta charset="UTF-8"</h1> ${user}<br> ${PWD}< /body> </ HTML >Copy the code