How does @RequestParam in Spring handle Guava's Optional?

Question

@RequestMapping(value = \"/contact.html\", method = RequestMethod.POST)
public final ModelAndView contact(
        @RequestParam(value = \"name\", required = false) Opti         


        

Answer 1

I recommend to use the Java 8 version: java.util.Optional. Look at the Oracle documentation in http://www.oracle.com/technetwork/articles/java/java8-optional-2175753.html. Also put a name to the variable, specially if your using Spring 3 or higher:.

import java.util.Optional;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class LoginController
{

    private static final Logger LOGGER = LoggerFactory.getLogger(LoginController.class);

    @RequestMapping(value = "/login", method = RequestMethod.GET)
    public ModelAndView getLoginPage(@RequestParam(name = "error", required = false) Optional errorMsg)
    {
        //error.ifPresent(LOGGER::debug); //Java 8 with Optional
        return new ModelAndView("login", "error", errorMsg);
    }

}

java.util.Optional is very useful for managing optional parametrers, like errors in Spring.