- Use Spring JDBC for executing plain SQL statements
- Use Spring Data JPA for more advanced use, e.g. mapping Java classes to tables and Java objects to rows, and take advantages of the Spring Data JPA API.
1. Add dependency for PostgreSQL JDBC Driver
Declare the following dependency in your project’s pom.xml file:org.postgresql postgresql runtime
This will use the default version specified by Spring Boot. If you want to explicitly specify a PostgreSQL JDBC version, refer to this page.
2. Configure Data Source Properties
Next, you need to specify some database connection information in the Spring Boot application configuration file ( application.properties ) as follows:
spring.datasource.url=jdbc:postgresql://localhost:5432/shopme spring.datasource.username=postgres spring.datasource.password=password
Here, the JDBC URL points to a PostgreSQL database server running on localhost. Update the JDBC URL, username and password according to your environment.
3. Connect to PostgreSQL Database with Spring JDBC
In the simplest case, you can use Spring JDBC with JdbcTemplate to work with a relational database. So add the following dependency to your Maven project file:
org.springframework.boot spring-boot-starter-jdbc
And the following code example is of a Spring Boot console program uses JdbcTemplate to execute a SQL Insert statement:
package net.codejava; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.CommandLineRunner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.jdbc.core.JdbcTemplate; @SpringBootApplication public class SpringJdbcTemplate2PostgreSqlApplication implements CommandLineRunner < @Autowired private JdbcTemplate jdbcTemplate; public static void main(String[] args) < SpringApplication.run(SpringJdbcTemplate2PostgreSqlApplication.class, args); >@Override public void run(String. args) throws Exception < String sql = "INSERT INTO students (name, email) VALUES (" + "'Nam Ha Minh', 'nam@codejava.net')"; int rows = jdbcTemplate.update(sql); if (rows >0) < System.out.println("A new row has been inserted."); >> >
This program will insert a new row into the students table in a PostgreSQL database, using Spring JDBC which is a thin API built on top of JDBC.
For details about using Spring JdbcTemplate, I recommend you to read this tutorial.
4. Connect to PostgreSQL Database with Spring Data JPA
If you want to map Java classes to tables and Java objects to rows and take advantages of an Object-Relational Mapping (ORM) framework like Hibernate, you can use Spring Data JPA. So declare the following dependency to your project:
org.springframework.boot spring-boot-starter-data-jpa
Besides the JDBC URL, username and password, you can also specify some additional properties as follows:
spring.jpa.hibernate.ddl-auto=update spring.jpa.show-sql=true spring.jpa.properties.hibernate.format_sql=true spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQL81Dialect
And you need to code an entity class (a POJO Java class) to map with the corresponding table in the database, as follows:
package net.codejava; import javax.persistence.*; @Entity @Table(name = "students") public class Student < @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Integer id; private String name; private String email; // getters and setters. >Then you need to declare a repository interface as follows: package net.codejava; import org.springframework.data.jpa.repository.JpaRepository; public interface StudentRepository extends JpaRepository And then you can use this repository in a Spring MVC controller or business class as follows:
@Controller public class StudentController < @Autowired private StudentRepository studentRepo; @GetMapping("/students") public String listAll(Model model) < ListlistStudents = studentRepo.findAll(); model.addAttribute("listStudents", listStudents); return "students"; > >
I recommend you to follow this article: Understand Spring Data JPA with Simple Example to learn more about Spring Data JPA.
Those are some code examples for connecting to PostgreSQL database in Spring Boot. As you have seen, Spring Boot greatly simplifies the programming, and you can choose to use Spring JDBC or Spring Data JPA.
Watch the following video to see the coding in action:
Related Articles:
- Understand Spring Data JPA with Simple Example
- Spring MVC with JdbcTemplate Example
- Spring Boot - Spring Data JPA - MySQL Example
Other Spring Boot Tutorials:
- How to create a Spring Boot Web Application (Spring MVC with JSP/ThymeLeaf)
- Spring Boot CRUD Example with Spring MVC – Spring Data JPA – ThymeLeaf - Hibernate - MySQL
- Spring Boot Hello World RESTful Web Services Tutorial
- Spring Boot Thymeleaf Form Handling Tutorial
- Spring Data JPA Paging and Sorting Examples
- Spring Boot Error Handling Guide
- Spring Boot Logging Basics
- Spring Security Role-based Authorization Tutorial
- Spring Security Customize Login and Logout
- How to Get Logged-in User's Details with Spring Security
- Spring Security: Prevent User from Going Back to Login Page if Already logged in
About the Author:
Nam Ha Minh is certified Java programmer (SCJP and SCWCD). He began programming with Java back in the days of Java 1.4 and has been passionate about it ever since. You can connect with him on Facebook and watch his Java videos on YouTube.
