Spring Boot 3 feature updates & best practices

Introduction: Spring Boot 3.0 will require Java 17 and spring framework 6 hence it becomes important for developers to get familiar with the changes and enhancements done in spring libraries as well as third-party library to adopt the new technology as part of best practices. In this blog I have tried to cover recent enhancements that are done in spring project using which code base can be simplified and developer experience can be improved.

Spring Framework 6 changes

package com.example.validatingforminput;

import am.ik.yavi.builder.ValidatorBuilder;
import am.ik.yavi.core.Validator;

public class PersonForm {

    public static Validator<PersonForm> validator = ValidatorBuilder.<PersonForm>of()
            .constraint(PersonForm::getName, "name", c -> c.notNull().greaterThanOrEqual(2).lessThanOrEqual(30))
            .constraint(PersonForm::getAge, "age", c -> c.notNull().greaterThanOrEqual(18))
            .build();

    // ...
}

package com.example.validatingforminput;

import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
import org.springframework.validation.Validator;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.PostMapping;


@Controller
public class WebController {

    @InitBinder
    void initBinder(WebDataBinder binder) {
        Validator personValidator = Validator.forInstanceOf(PersonForm.class, PersonForm.validator.toBiConsumer(Errors::rejectValue));
        binder.addValidators(personValidator);
    }

    @GetMapping("/")
    public String showForm(PersonForm personForm) {
        return "form";
    }

    @PostMapping("/")
    public String checkPersonInfo(@Validated PersonForm personForm, BindingResult bindingResult) {

        if (bindingResult.hasErrors()) {
            return "form";
        }

        return "redirect:/results";
    }
}

protected final <T> T findSingle(String query) {
    return (T) DataAccessUtils.optionalResult(em.createNamedQuery(query).getResultList());
}​

    @Scheduled(scheduler="${name}",cron = "${scheduler.pay.partner.transaction.cron.expression}", zone = "UTC")

public abstract class StringUtils {

	public static String reverseString(String input) {
		StringBuilder backwards = new StringBuilder(input.length());
		for (int i = 0; i < input.length(); i++) {
			backwards.append(input.charAt(input.length() - 1 - i));
		}
		return backwards.toString();
	}
}

ExpressionParser parser = new SpelExpressionParser();

EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
context.setVariable("reverseString",
		StringUtils.class.getDeclaredMethod("reverseString", String.class));

String helloWorldReversed = parser.parseExpression(
		"#reverseString('hello')").getValue(context, String.class);

<SpringProfile name=”dev | test”>
<! — configuration to be enabled when the “dev” or “test” profiles are active →
</SpringProfile>

<SpringProfile name=”staging”>
<! — configuration to be enabled when the “staging” profile is active →
</SpringProfile>

<SpringProfile name=”!production”>
<! — configuration to be enabled when the “production” profile is not active →
</SpringProfile>

<Properties> <Property name=”applicationName”>${spring:spring.application.name}</property> </Properties>
​