可以通过在Spring Boot中进行依赖注入来完成请求验证吗？

Question

== Background ==
I'm used to the dependency injections available in Laravel, where you can make a class that extends the request-class, and put all the validation in it, and then re use it in multiple controller methods.

== Current code ===
I'm currently trying to do a project in Java Spring Boot, and my controller methods now looks like this:

    @RequestMapping("/list")
    @ResponseBody
    public DTResponse<Name> list(
            @RequestParam(defaultValue = "0") int draw,
            @RequestParam(defaultValue = "0") int start,
            @RequestParam(defaultValue = "0") int length,
            @RequestParam(name="search[value]", defaultValue = "") String search,
            @RequestParam(name="columns[0][search][value]", defaultValue = "") String firstname,
            @RequestParam(name="columns[1][search][value]", defaultValue = "") String lastname,
            @RequestParam(name="order[0][column]", defaultValue = "0") int sortColumn,
            @RequestParam(name="order[0][dir]", defaultValue = "asc") String sortOrder,
            @CookieValue String language,
            HttpServletResponse response,
            HttpServletRequest request
    )

And forward most of them to a validation function.

== Future ==
I'd like to replace most of thus rows with a class, that can do the validation, and abstract away some of the request parameters in to methods, so they easy can be reused on multiple methods.

== Question ==
How do I write a class, that can be injected in the controller methods, and run validation, and have helper methods that can parse the request params?

== Alternativ ==
Can I build a static function, that can get the injected request params, http-servlets and cookie?

Answer 1

To add to @Antoniossss' answer...

The @Valid annotation is the way to go here.

Here is a small example.

@ModelAttribute("command")
public DTRequest setupCommand() {

    return new DTRequest;
}

@RequestMapping(value = "/list")
@ResponseBody
public DTResponse<Name> list(@ModelAttribute("command") @Valid DTRequest request, BindingResult bindingResult, RedirectAttributes redirectAttributes) {

    DTResponse<Name> response;

    if (bindingResult.hasErrors()) {

        // Do something here to let the client know that something went wrong.
        // You can throw and exception and catch it one way or another...

    } else {

        // Do your real work here...
    }

    return response;
}

Your command object could look like the following.

NOTE

I STRONGLY suggest using string for all you incoming values because if the value submitted by the client doesn't match the expected type (int, float, boolean, etc...), spring will throw an exception that you have little control over and that exception can be quite cryptic.

The default type that all values can come in as is String and therefore recommend using that as the lowest common denominator and then checking to see if the entered value can be cast to the desired type, in this case, int/integer.

public class DTRequest {

    @Digits
    private String draw = "0";

    @Digits
    private String start = "0";

    @Digits
    private String length = "0";

    // etc... per field.

    // Setters and getters...
    public void setDraw(String draw) {
        this.draw = draw;
    }

    public String getDraw() {
        return this.draw;
    }

    public int getDrawAsInt() {
        return Integer.valueOf(this.draw);
    }

    // etc... per setters and getters...
}

Answer 2

Yes, you can simply use @Valid annotation on arguments to invoke either built-in or custom validations. Check the official documentation

https://docs.spring.io/spring/docs/4.1.x/spring-framework-reference/html/validation.html