Hibernate Validatorによるバリデーション

package org.acme.validation;

import jakarta.validation.constraints.NotBlank;
import jakarta.validation.constraints.Min;

public class Book {

    @NotBlank(message="Title may not be blank")
    public String title;

    @NotBlank(message="Author may not be blank")
    public String author;

    @Min(message="Author has been very lazy", value=1)
    public double pages;
}

package org.acme.validation;

import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;

@Path("/books")
public class BookResource {

    @Inject
    Validator validator; (1)

    @Path("/manual-validation")
    @POST
    public Result tryMeManualValidation(Book book) {
        Set<ConstraintViolation<Book>> violations = validator.validate(book);
        if (violations.isEmpty()) {
            return new Result("Book is valid! It was validated by manual validation.");
        } else {
            return new Result(violations);
        }
    }
}

public static class Result {

    Result(String message) {
        this.success = true;
        this.message = message;
    }

    Result(Set<? extends ConstraintViolation<?>> violations) {
        this.success = false;
        this.message = violations.stream()
             .map(cv -> cv.getMessage())
             .collect(Collectors.joining(", "));
    }

    private String message;
    private boolean success;

    public String getMessage() {
        return message;
    }

    public boolean isSuccess() {
        return success;
    }

}

@Path("/end-point-method-validation")
@POST
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
public Result tryMeEndPointMethodValidation(@Valid Book book) {
    return new Result("Book is valid! It was validated by end point method validation.");
}

package org.acme.validation;

import jakarta.enterprise.context.ApplicationScoped;
import jakarta.validation.Valid;

@ApplicationScoped
public class BookService {

    public void validateBook(@Valid Book book) {
        // your business logic here
    }
}

@Inject BookService bookService;

@Path("/service-method-validation")
@POST
public Result tryMeServiceMethodValidation(Book book) {
    try {
        bookService.validateBook(book);
        return new Result("Book is valid! It was validated by service method validation.");
    } catch (ConstraintViolationException e) {
        return new Result(e.getConstraintViolations());
    }
}