Spring Boot in 20 Minutes

Prerequisites

What is Spring Boot?

Features of Spring Boot

Spring Boot vs Other Java Web Frameworks

Chapter 2: Spring Boot The Framework

Business Layer

Infrastructure Layer

Presentation Layer

CHAPTER 3: A Web Application with Spring Boot

Set Up Your Development Environment

Generate a Spring Boot Project with Spring Initializr

Import the Project into Your IDE

java {
	sourceCompatibility = '20'
	targetCompatibility = '20'
	project.buildDir = 'target'
}

Create A Base Entity

package com.codaholic.todo.domain.common;
import com.fasterxml.jackson.annotation.JsonIgnore;
import jakarta.persistence.*;
import lombok.Data;
import org.springframework.data.annotation.CreatedDate;
import org.springframework.data.annotation.LastModifiedDate;
import java.io.Serial;
import java.io.Serializable;
import java.time.LocalDateTime;
import java.util.UUID;
@Data
@MappedSuperclass
public abstract class BaseEntity implements Serializable {
    @Serial
    private static final long serialVersionUID = 5L;
    @Id
    @GeneratedValue
    private UUID id;
    @JsonIgnore
    @CreatedDate
    @Column(name = "created_dt")
    @Temporal(TemporalType.TIMESTAMP)
    private LocalDateTime createdDate;
    @JsonIgnore
    @LastModifiedDate
    @Column(name = "updated_dt")
    @Temporal(TemporalType.TIMESTAMP)
    private LocalDateTime updatedDate;
    @JsonIgnore
    @Version
    private Integer version;
}

Create A Todo Entity

package com.codaholic.todo.domain.entities;
import com.codaholic.todo.domain.common.BaseEntity;
import com.codaholic.todo.domain.enums.Status;
import jakarta.persistence.*;
import jakarta.validation.constraints.NotEmpty;
import jakarta.validation.constraints.NotNull;
import lombok.*;
import java.time.LocalDateTime;
@Data
@Entity
@Builder
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "todo")
@EqualsAndHashCode(callSuper = false)
public class Todo extends BaseEntity {
    @NotEmpty(message = "Name cannot be blank")
    private String Name;
    @NotNull(message = "Start Time cannot be blank")
    private LocalDateTime StartTime;
    @NotNull(message = "End Time cannot be blank")
    private LocalDateTime EndTime;
    @Builder.Default
    @Enumerated(EnumType.STRING)
    private Status TaskStatus = Status.PENDING;
}

Create an Enum, Status

package com.codaholic.todo.domain.enums;
import com.fasterxml.jackson.annotation.JsonFormat;
@JsonFormat(shape = JsonFormat.Shape.STRING)
public enum Status {
    PENDING,
    COMPLETED,
    CANCELED
}

Create A TodoRepository

package com.codaholic.todo.infrastructure.repository;
import com.codaholic.todo.domain.entities.Todo;
import org.springframework.data.jpa.repository.JpaRepository;
import java.util.UUID;
public interface TodoRepository extends JpaRepository<Todo, UUID> {
}

Create A TodoService

package com.codaholic.todo.infrastructure.services;
import com.codaholic.todo.domain.entities.Todo;
import com.codaholic.todo.infrastructure.repository.TodoRepository;
import org.springframework.stereotype.Service;
import java.util.List;
import java.util.UUID;
@Service
public class TodoService {
    private final TodoRepository repo;
    TodoService(TodoRepository repo){
        this.repo = repo;
    }
    public List<Todo> getAllTodos() {
        return repo.findAll();
    }
    public Todo createTodo(Todo todo) {
        return repo.save(todo);
    }
    public Todo getTodoById(UUID id) {
        return repo.findById(id)
                .orElseThrow(() -> new IllegalArgumentException("Todo not found"));
    }
    public Todo updateTodo(UUID id, Todo todoDetail) {
        Todo todo = repo.findById(id)
                .orElseThrow(() -> new IllegalArgumentException("Todo not found"));
        todo.setName(todoDetail.getName());
        todo.setStartTime(todoDetail.getStartTime());
        todo.setEndTime(todoDetail.getEndTime());
        todo.setTaskStatus(todoDetail.getTaskStatus());
        return repo.save(todo);
    }
    public void deleteTodo(UUID id) {
        repo.deleteById(id);
    }
}

Create A TodoController

package com.codaholic.todo.webapi.controllers;
import com.codaholic.todo.domain.entities.Todo;
import com.codaholic.todo.infrastructure.services.TodoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import java.util.List;
import java.util.UUID;
@RestController
@RequestMapping("/api/todo")
public class TodoController {
    private final TodoService todoService;
    @Autowired
    public TodoController(TodoService todoService) {
        this.todoService = todoService;
    }
    @GetMapping
    public ResponseEntity<List<Todo>> getAllTodos() {
        List<Todo> todos = todoService.getAllTodos();
        return ResponseEntity.ok(todos);
    }
    @PostMapping
    public ResponseEntity<Todo> createTodo(@RequestBody Todo todo) {
        Todo createdTodo = todoService.createTodo(todo);
        return ResponseEntity.status(HttpStatus.CREATED).body(createdTodo);
    }
    @GetMapping("/{id}")
    public ResponseEntity<Todo> getTodoById(@PathVariable UUID id) {
        Todo product = todoService.getTodoById(id);
        return ResponseEntity.ok(product);
    }
    @PutMapping("/{id}")
    public ResponseEntity<Todo> updateTodo(@PathVariable UUID id,@RequestBody Todo todoDetails) {
        Todo updatedTodo = todoService.updateTodo(id, todoDetails);
        return ResponseEntity.ok(updatedTodo);
    }
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteProduct(@PathVariable UUID id) {
        todoService.deleteTodo(id);
        return ResponseEntity.noContent().build();
    }
}

Set up the H2 Database

spring:
  main:
    banner-mode: off
  output:
    ansi:
      enabled: always
  h2:
    console:
      enabled: true
  datasource:
    url: jdbc:h2:mem:testdb
    driverClassName: org.h2.Driver
  jpa:
    database-platform: org.hibernate.dialect.H2Dialect
    open-in-view: false
    show-sql: true
    hibernate:
      ddl-auto: create-drop
server:
  address: ${APP_ADDRESS}
  port: ${APP_PORT}
  compression:
    enabled: true
  error:
    include-message: always
  shutdown: "graceful"
logging:
  level:
    root: WARN
    org.springframework.web: DEBUG
    org.hibernate: ERROR
  file:
    name: logs/todo.log

Setup Environmental Variables

export APP_PORT=3000
export APP_ADDRESS=127.0.0.1

Build and Run the Application

source .env.dev && ./gradlew bootRun

Frequently Asked Questions