Backend con Java Spring Boot + CRUD API REST + PostgreSQL

En este tutorial vamos a aprender a crear una CRUD usando Spring Boot con la base de datos de PostgreSQL. Crearemos una API REST que desarrolle las peticiones CRUD (Create, Read, Update, Delete) usando el Framework Backend de Java.

Crear proyecto

Es el link para generar proyecto

https://start.spring.io/#!type=maven-project&language=java&platformVersion=3.0.2&packaging=jar&jvmVersion=1.8&groupId=com.tutofox&artifactId=demo&name=demo&description=Demo%20project%20for%20Spring%20Boot&packageName=com.tutofox.demo&dependencies=data-rest,web,devtools,data-jpa,validation,postgresql

Properties

src\main\resources\application.properties

Definir el usuario, base datos, contraseña, y configuracion de Hibernate, JPA, etc.

spring.datasource.url= jdbc:postgresql://localhost:5432/tutofox
spring.datasource.username= postgres
spring.datasource.password= 12345

spring.jpa.properties.hibernate.jdbc.lob.non_contextual_creation= true
spring.jpa.properties.hibernate.dialect= org.hibernate.dialect.PostgreSQLDialect

# Hibernate ddl auto (create, create-drop, validate, update)
spring.jpa.hibernate.ddl-auto= update

Dependencias

pom.xml

<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-rest</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		
		<dependency> 
		    <groupId>org.springframework.boot</groupId> 
		    <artifactId>spring-boot-starter-validation</artifactId> 
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
			<scope>runtime</scope>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.postgresql</groupId>
			<artifactId>postgresql</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>


</dependency>

Entity

Primero crear el modelo entity donde se encarga definir los campos y tipo de datos.
src\main\java\com\tutofox\demo\entity\Person.java

package com.tutofox.demo.entity; 
import java.io.Serializable;
import java.util.Date;

import org.hibernate.validator.constraints.Length;
import org.springframework.data.annotation.CreatedDate;

import jakarta.persistence.Column;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import jakarta.persistence.Table;
import jakarta.persistence.Temporal;
import jakarta.persistence.TemporalType;
import jakarta.validation.constraints.Max;
import jakarta.validation.constraints.NotBlank;
import jakarta.persistence.Entity;

@Entity
@Table(name="persons")
public class Person implements Serializable {
 
	private static final long serialVersionUID = 1L;

	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	@Column(name = "id")
	private Long id;
	
	@NotBlank 
	@Column(name = "name")
	private String name;
	
	@Column(name = "address")
	private String address;
	
	@Column(name = "phone") 
	private Integer phone;
	
	@Column(name="create_at")
	@CreatedDate
	private Date createAt;

	public Long getId() {
		return id;
	}

	public void setId(Long id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

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

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	public Integer getPhone() {
		return phone;
	}

	public void setPhone(Integer phone) {
		this.phone = phone;
	}

	public Date getCreateAt() {
		return createAt;
	}

	public void setCreateAt(Date createAt) {
		this.createAt = createAt;
	} 
}

Dao

Dao es un objeto de acceso a datos que trae todos los métodos de consultas.
src\main\java\com\tutofox\demo\repository\PersonDao.java

package com.tutofox.demo.repository;

import org.springframework.data.jpa.repository.JpaRepository;

import com.tutofox.demo.entity.Person;

public interface PersonDao extends JpaRepository<Person, Long> {

}

Services / Servicios

El servicio es el encargado donde comunica entre el controlador y repositorio donde se encarga las consultas.
src\main\java\com\tutofox\demo\services\PersonServiceImpl.java

package com.tutofox.demo.services;

import java.util.List;

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

import com.tutofox.demo.entity.Person;
import com.tutofox.demo.repository.PersonDao;

import jakarta.transaction.Transactional;

@Service
public class PersonServiceImpl implements PersonService{

	@Autowired
	private PersonDao personDao;
	
	@Override
	@Transactional
	public List<Person> findAll() {
		return (List<Person>) personDao.findAll();
	}

	@Override
	@Transactional
	public Person save(Person person) {
		return personDao.save(person);
	}

	@Override 
	public Person findById(Long id) {
		return personDao.findById(id).orElse(null);
	}

	@Override
	@Transactional
	public void delete(Person person) {
		personDao.delete(person);
		
	}

}

src\main\java\com\tutofox\demo\services\PersonService.java

package com.tutofox.demo.services;

import java.util.List;

import com.tutofox.demo.entity.Person;

public interface PersonService {
	public List<Person> findAll();
	
	public Person save(Person person);
	
	public Person findById(Long id);
	
	public void delete(Person person);
}

Controller / Controlador

El controlador es el que encarga la interacción de API y realiza las solicitudes al servicio que trae los datos y retorna la respuesta de peticón.

src\main\java\com\tutofox\demo\controller\PersonController.java

package com.tutofox.demo.controller;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

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.PathVariable;
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.RestController;

import com.tutofox.demo.entity.Person;
import com.tutofox.demo.services.PersonService;

@RestController
@RequestMapping("/api/v1")
public class PersonController {
	
	@Autowired
	private PersonService personService;
	
	@GetMapping(value="/persons")
	public ResponseEntity<Object> get(){ 
		Map<String, Object> map = new HashMap<String, Object>();
		try {
			List<Person> list  = personService.findAll();
			return new ResponseEntity<Object>(list,HttpStatus.OK);
		} 
		catch (Exception e) {
			map.put("message", e.getMessage());
			return new ResponseEntity<>( map, HttpStatus.INTERNAL_SERVER_ERROR);
		} 
 	}
	
	@GetMapping(value="/persons/{id}")
	public ResponseEntity<Object> getById(@PathVariable Long id){ 
		try {
			Person data  = personService.findById(id);
			return new ResponseEntity<Object>(data,HttpStatus.OK);
		} 
		catch (Exception e) {
			Map<String, Object> map = new HashMap<String, Object>();
			map.put("message", e.getMessage());
			return new ResponseEntity<>( map, HttpStatus.INTERNAL_SERVER_ERROR);
		} 
 	}

	@PostMapping(value="/persons")
	public ResponseEntity<Object> create(@RequestBody Person person){ 
		Map<String, Object> map = new HashMap<String, Object>();
		try {
			Person res = personService.save(person);  
			return new ResponseEntity<Object>(res,HttpStatus.OK);
		} 
		catch (Exception e) {
			map.put("message", e.getMessage());
			return new ResponseEntity<>( map, HttpStatus.INTERNAL_SERVER_ERROR);
		} 
 	}
	
	@PutMapping("/persons/{id}")
	public ResponseEntity<Object> update(@RequestBody Person person, @PathVariable Long id){ 
		Map<String, Object> map = new HashMap<String, Object>();
		try {
			
			Person currentPerson = personService.findById(id);
			
			currentPerson.setName(person.getName());
			currentPerson.setAddress(person.getAddress());
			currentPerson.setPhone(person.getPhone()); 
			
			Person res = personService.save(person);
			
			return new ResponseEntity<Object>(res,HttpStatus.OK);
		} 
		catch (Exception e) {
			map.put("message", e.getMessage());
			return new ResponseEntity<>( map, HttpStatus.INTERNAL_SERVER_ERROR);
		} 
 	}
	
	@DeleteMapping("/persons/{id}")
	public ResponseEntity<Object> delete(@PathVariable Long id){ 
		Map<String, Object> map = new HashMap<String, Object>();
		try { 
			Person currentPerson = personService.findById(id); 
			personService.delete(currentPerson);
			map.put("deleted", true);
			return new ResponseEntity<Object>(map,HttpStatus.OK);
		} 
		catch (Exception e) {
			map.put("message", e.getMessage());
			return new ResponseEntity<>( map, HttpStatus.INTERNAL_SERVER_ERROR);
		} 
 	}
}

Prueba de Servicios API

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