BindingResult 作用原理

controller代碼

@RequestMapping("")
    public String index(@Valid User user , BindingResult bindingResult){
        if (bindingResult.hasErrors()){
            List<ObjectError> allErrors = bindingResult.getAllErrors();
            ObjectError objectError = allErrors.get(0);
            System.out.println(objectError.getDefaultMessage());
            System.out.println(objectError.getObjectName());
            System.out.println(allErrors);
        }
        return "index";
    }

請求先來到DispatcherServlet的doDispatch 方法，最終會調用ModelAttributeMethodProcessor#resolveArgument方法

調用DataBinder#validate方法后調用ConstraintTree#validateSingleConstraint，由它來調用具體的驗證器

 

具體的驗證器