Introdução ao MariaDB usando Docker, Java Spring e JDBC

MariaDB e Java Database Connectivity (JDBC)

Requisitos

• Cliente MariaDB
• Docker
• Java (v. 8+)
• Curl (para testar os endpoints da API)

Criando uma nova instância MariaDB usando o Docker

$ docker run -p 3306:3306 -d --name mariadb -eMARIADB_ROOT_PASSWORD=Password123! mariadb/server:10.4 

$ docker ps

Conectando-se ao MariaDB

Existem muitos clientes SQL disponíveis à solta. Para simplificar, optei por demonstrar como usar o cliente oficial do MariaDB, mas certamente sinta-se à vontade para usar o cliente que preferir.

$ mariadb --host 127.0.0.1 -P 3306 --user root -pPassword123!

CREATE DATABASE todo;

CREATE TABLE todo.tasks (
  id INT(11) unsigned NOT NULL AUTO_INCREMENT,
  description VARCHAR(500) NOT NULL,
  completed BOOLEAN NOT NULL DEFAULT 0,
  PRIMARY KEY (id)
);

Introdução ao Java Spring, JDBC e MariaDB

• Lombok: Uma biblioteca que eliminará a necessidade de criar código de placa de caldeira (por exemplo, getters, setters) dentro dos objetos de domínio.
• Spring Web: Uma biblioteca para criar e expor endpoints de API RESTful.
• JPA de dados Spring: Uma biblioteca que fornece abstrações para ajudar a eliminar o código de placa de caldeira para conexão e comunicação com bancos de dados.

<dependency>             
   <groupId>org.mariadb.jdbc</groupId>           
   <artifactId>mariadb-java-client</artifactId>
   <version>2.6.0</version>
</dependency>

package com.mariadb.todo.domain;

import javax.persistence.*;

import lombok.Data;

@Data
@Entity
@Table(name = "tasks")
public class Task {
    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String description;
    private Boolean completed = false;
}

package com.mariadb.todo.repositories;

import com.mariadb.todo.domain.Task;

import org.springframework.data.repository.CrudRepository;

public interface TaskRepository extends CrudRepository<Task, Integer> {
}

package com.mariadb.todo.services;

import java.util.Optional;

import com.mariadb.todo.domain.Task;
import com.mariadb.todo.repositories.TaskRepository;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

// Registered as a Spring Service (Component)
@Service
public class TaskService {

    // Automatically instantiate (via Spring IoC) 
    @Autowired
    private TaskRepository repository;

    // 
    public Boolean isValid(final Task task) {
        if (task != null && !task.getDescription().isEmpty()) {
            return true;
        }
        return false;
    }

    // Get all records from the tasks table
    public Iterable<Task> getAllTasks() {
        return this.repository.findAll();
    }

    // Save a new task record
    public Task createTask(final Task task) {
        return this.repository.save(task);
    }

    // Update an existing task record
    @Transactional
    public Task updateTask(final Task task) {
        Optional<Task> ot = this.repository.findById(task.getId());
        Task t = ot.get();
        t.setDescription(task.getDescription());
        t.setCompleted(task.getCompleted());
        return this.repository.save(t);
    }

    // Delete the task record by specified id
    @Transactional
    public void deleteTask(final int id){
        Optional<Task> ot = this.repository.findById(id);
        Task t = ot.get();
        this.repository.delete(t);
    }
}

package com.mariadb.todo.controllers;

import com.mariadb.todo.domain.Task;
import com.mariadb.todo.services.TaskService;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api/tasks")
public class TaskController {

    @Autowired
    private TaskService service;

    // Get all tasks
    @GetMapping()
    public ResponseEntity<Iterable<Task>> get() {
        return ResponseEntity.ok(this.service.getAllTasks());
    }

    // Create a new task
    @PostMapping()
    public ResponseEntity<Task> post(@RequestBody Task task) {
        if (service.isValid(task)) {
            return ResponseEntity.ok(this.service.createTask(task));
        }
        return ResponseEntity.status(HttpStatus.I_AM_A_TEAPOT).build();
    }

    // Update a task
    @PutMapping()
    public ResponseEntity<Task> put(@RequestBody Task task) {
        if (service.isValid(task)) {
            return ResponseEntity.ok(this.service.updateTask(task));
        }
        return ResponseEntity.status(HttpStatus.I_AM_A_TEAPOT).build();
    }

    // Delete a task
    @DeleteMapping()
    public ResponseEntity<Void> delete(@RequestParam int id) {
        if (id > 0) {
            this.service.deleteTask(id);
            return ResponseEntity.ok().build();
        }
        return ResponseEntity.status(HttpStatus.I_AM_A_TEAPOT).build();
    }
}

$ mvn package

$ mvn spring-boot:run

$ curl --header "Content-Type: application/json" \
  --request POST \
  --data '{"description":"A New Task"}' \
  http://localhost:8080/api/tasks

$ curl https://localhost:8080/api/tasks

{ "id": 1, "description": "A New Task", "completed": false }

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