Spring Framework - Method Validations Examples

package com.logicbig.example;

import javax.validation.constraints.Email;
import javax.validation.constraints.NotEmpty;

public class User {
    @NotEmpty
    private String name;
    @Email
    private String email;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", email='" + email + '\'' +
                '}';
    }
}

package com.logicbig.example;

import org.springframework.stereotype.Component;
import org.springframework.validation.annotation.Validated;
import javax.validation.Valid;
import javax.validation.constraints.NotNull;

@Component
@Validated
public class UserTask {

    public void registerUser(@NotNull @Valid User user){
        System.out.println("registering user: "+ user);
    }
}

package com.logicbig.example;

import org.springframework.stereotype.Component;
import org.springframework.validation.annotation.Validated;
import javax.validation.constraints.FutureOrPresent;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;
import java.time.LocalDateTime;

@Validated
@Component
public class ReportTask {
    public @Pattern(regexp = "[0-3]") String createReport(@NotNull @Size(min = 3, max = 20) String name,
                                                          @NotNull @FutureOrPresent LocalDateTime startDate) {
        return "-1";
    }
}

package com.logicbig.example;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
import org.springframework.validation.beanvalidation.MethodValidationPostProcessor;
import javax.validation.ConstraintViolation;
import javax.validation.ConstraintViolationException;
import javax.validation.Validator;
import java.time.LocalDateTime;
import java.util.Comparator;
import java.util.Set;

@Configuration
@ComponentScan
public class AppConfig {
    @Bean
    public Validator validatorFactory() {
        return new LocalValidatorFactoryBean();
    }

    @Bean
    public MethodValidationPostProcessor methodValidationPostProcessor() {
        return new MethodValidationPostProcessor();
    }

    public static void main(String[] args) {
        ApplicationContext context =
                new AnnotationConfigApplicationContext(AppConfig.class);

        ReportTask task = context.getBean(ReportTask.class);
        System.out.println("-- calling ReportTask#createReport() --");
        System.out.println("-- with invalid parameters --");
        try {
            String status = task.createReport("", LocalDateTime.now().minusMinutes(30));
            System.out.println(status);
        } catch (ConstraintViolationException e) {
           printValidationError(e);
        }
        System.out.println("-- with valid parameters but invalid return value --");
        try {
            String status = task.createReport("create reports", LocalDateTime.now().plusMinutes(30));
            System.out.println(status);
        } catch (ConstraintViolationException e) {
            printValidationError(e);
        }

        UserTask userTask = context.getBean(UserTask.class);
        System.out.println("-- calling UserTask#registerUser() --");
        User user = new User();
        user.setEmail("tony-example.com");
        try {
            userTask.registerUser(user);
        } catch (ConstraintViolationException e) {
             printValidationError(e);
        }
    }

    private static void printValidationError(ConstraintViolationException e) {
        System.err.println("validation errors:");
        e.getConstraintViolations().stream().sorted(Comparator.comparing(v->v.getPropertyPath().toString()))
         .map(v -> v.getMessage()).forEach(System.out::println);
    }
}