@InitBinder

Customizing WebDataBinder initialization
To customize request parameter binding with PropertyEditors, etc. via Spring's WebDataBinder, you can either use @InitBinder-annotated methods within your controller or externalize your configuration by providing a custom WebBindingInitializer.

Customizing data binding with @InitBinder
Annotating controller methods with @InitBinder allows you to configure web data binding directly within your controller class. @InitBinder identifies methods which initialize the WebDataBinder which will be used for populating command and form object arguments of annotated handler methods.
Such init-binder methods support all arguments that @RequestMapping supports, except for command/form objects and corresponding validation result objects. Init-binder methods must not have a return value. Thus, they are usually declared as void. Typical arguments include WebDataBinder in combination with WebRequest or java.util.Locale, allowing code to register context-specific editors.
The following example demonstrates the use of @InitBinder for configuring a CustomDateEditor for all java.util.Date form properties.

@Controller
public class MyFormController {

    @InitBinder
    public void initBinder(WebDataBinder binder) {
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        dateFormat.setLenient(false);
        binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, false));
    }

    // ...
}

WebDataBinder是用来绑定请求参数到指定的属性编辑器，可以继承WebBindingInitializer来实现一个全部controller共享的dataBiner

@Component
public class CommonBindingInitializer implements WebBindingInitializer {

    public void initBinder(WebDataBinder binder, WebRequest request) {
        SimpleDateFormat dateFormat = new SimpleDateFormat(ERPUtil.ISO_DATE_MASK);
        dateFormat.setLenient(false);
        binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, true));
        binder.registerCustomEditor(String.class, new StringTrimmerEditor(false));
    }
}

也可以在某个单独的contorller里定义一个dataBinder，使用@InitBinder注解就可以实现

PS：WebDataBinder是用来绑定请求参数到指定的属性编辑器.由于前台传到controller里的值是String类型的，当往Model里Set这个值的时候，如果set的这个属性是个对象，Spring就会去找到对应的EDITOR进行转换，然后再SET进去