有 @ModelAttribute 標記的方法, 會在每個目標方法執行之前被 SpringMVC 呼叫

	<form action="springmvc/TestModelAttribute" method="post">
		使用者名稱<input type="text" name="username" value="wang"/><br/>
		年齡<input type="text" name="age"  value="12"/>
		<input type="submit" value="測試ModelAttribute"
 
>
	</form>

	@ModelAttribute
	public void getUser(@RequestParam(value="username",required=false) String username,Map<String,Object> map){
		if(username!=null){
			User user=new User("wang","123",50);
			System.out.println("xiugai => username:"+user.getUsername()+",password:"+user.getPassword
 
()+",Age:"+user.getAge());
			//放入的鍵 是類名首字母小寫
			map.put("user", user);
		}
	}
	@RequestMapping("/TestModelAttribute")
	public String TestModelAttribute(User user){
		System.out.println("gengxin => username:"+user.getUsername()+",password:"+user.getPassword()+",Age:"+user.getAge());
		return SUCCESS;
 

	}

所以，執行TestModelAttribute方法前，先執行getUser方法