Spring Boot JdbcTemplate example: CRUD Rest API

In this tutorial, we’re gonna build a Spring Boot Rest CRUD API example that use Spring JdbcTemplate to interact with H2 database. You’ll know:

How to configure Spring Data JDBC to work with Database
How to define Data Models and Repository interfaces
Way to create Spring Rest Controller to process HTTP requests
Way to use Spring JdbcTemplate to interact with H2 Database

Exception Handling:
– Spring Boot @ControllerAdvice & @ExceptionHandler example
– @RestControllerAdvice example in Spring Boot

Unit Test:
Spring Boot – Rest Controller Unit Test with @WebMvcTest
Or Documentation: Spring Boot + Swagger 3 example (with OpenAPI 3)

Using Spring Data JPA instead:
Spring Boot JPA + H2 example: Build a CRUD Rest APIs

Other Databases:
– Spring Boot JdbcTemplate example with MySQL
– Spring Boot JdbcTemplate example with PostgreSQL
– Spring Boot JdbcTemplate example with SQL Server
– Spring Boot JdbcTemplate example with Oracle

Contents

Overview
Technology
Project Structure
Create & Setup Spring Boot project
Configure Spring Data and H2 database
Define Data Model
Create Repository
Create Spring Rest APIs Controller
Run & Check
Conclusion
Source Code
Further Reading

Overview of Spring Boot JdbcTemplate CRUD example

We will build a Spring Boot Rest API using Spring Data Jdbc with H2 Database for a Tutorial application that:

Each Tutorial has id, title, description, published status.
Apis help to create, retrieve, update, delete Tutorials.
Apis also support custom finder methods such as find by published status or by title.

These are APIs that we need to provide:

Methods	Urls	Actions
POST	/api/tutorials	create new Tutorial
GET	/api/tutorials	retrieve all Tutorials
GET	/api/tutorials/:id	retrieve a Tutorial by `:id`
PUT	/api/tutorials/:id	update a Tutorial by `:id`
DELETE	/api/tutorials/:id	delete a Tutorial by `:id`
DELETE	/api/tutorials	delete all Tutorials
GET	/api/tutorials/published	find all published Tutorials
GET	/api/tutorials?title=[keyword]	find all Tutorials which title contains `keyword`

– We make CRUD operations & finder methods with Spring Data Jdbc.
– The database will be H2 Database (in memory or on disk) by configuring project dependency & datasource.

This Spring Boot App works with Client in one of these posts:

Simple HTTP Client using Axios
Simple HTTP Client using Fetch API
Angular 8 / Angular 10 / Angular 11 / Angular 12 / Angular 13 / Angular 14

/ Angular 15

Vue 2 / Vue 3
React / React Redux

Technology

Java 8
Spring Boot 2.5.4 (with Spring Web MVC, Spring Data JDBC)
H2 Database
Maven 3.6.1

Project Structure

Let me explain it briefly.

– Tutorial data model class corresponds to entity and table tutorials.
– TutorialRepository is an interface that provides abstract methods for CRUD Operations and custom finder methods. It will be autowired in TutorialController.
– JdbcTutorialRepository implements TutorialRepository. It uses JdbcTemplate for executing SQL queries or updates to interact with Database.
– TutorialController is a RestController which has request mapping methods for RESTful requests such as: getAllTutorials, createTutorial, updateTutorial, deleteTutorial, findByPublished…
– Configuration for Spring Datasource, H2 database in application.properties.
– pom.xml contains dependencies for Spring Boot Web, JDBC and H2 Database.

Create & Setup Spring Boot project

Use Spring web tool or your development tool (Spring Tool Suite, Eclipse, Intellij) to create a Spring Boot project.

Then open pom.xml and add these dependencies:

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-data-jdbc</artifactId>
</dependency>

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>

<dependency>
	<groupId>com.h2database</groupId>
	<artifactId>h2</artifactId>
	<scope>runtime</scope>
</dependency>

Configure Spring Data and H2 database

Under src/main/resources folder, open application.properties and write these lines.

spring.h2.console.enabled=true
# default path: h2-console
spring.h2.console.path=/h2-ui
 
spring.datasource.url=jdbc:h2:file:H:/h2db/testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=

spring.h2.console.enabled=true tells the Spring to start H2 Database administration tool and you can access this tool on the browser: http://localhost:8080/h2-console.
spring.h2.console.path=/h2-ui is for H2 console’s url, so the default url http://localhost:8080/h2-console will change to http://localhost:8080/h2-ui.
spring.datasource.url: jdbc:h2:mem:[database-name] for In-memory database and jdbc:h2:file:[path/database-name] for disk-based database.
spring.datasource.username & spring.datasource.password properties are the same as your database installation.

Define Data Model

Our Data model is Tutorial with four fields: id, title, description, published.
In model package, we define Tutorial class.

model/Tutorial.java

package com.bezkoder.spring.jdbc.model;

public class Tutorial {

  private long id;
  private String title;
  private String description;
  private boolean published;

  public Tutorial() {

  }
  
  public Tutorial(long id, String title, String description, boolean published) {
    this.id = id;
    this.title = title;
    this.description = description;
    this.published = published;
  }

  public Tutorial(String title, String description, boolean published) {
    this.title = title;
    this.description = description;
    this.published = published;
  }
  
  public void setId(long id) {
    this.id = id;
  }
  
  public long getId() {
    return id;
  }

  public String getTitle() {
    return title;
  }

  public void setTitle(String title) {
    this.title = title;
  }

  public String getDescription() {
    return description;
  }

  public void setDescription(String description) {
    this.description = description;
  }

  public boolean isPublished() {
    return published;
  }

  public void setPublished(boolean isPublished) {
    this.published = isPublished;
  }

  @Override
  public String toString() {
    return "Tutorial [id=" + id + ", title=" + title + ", desc=" + description + ", published=" + published + "]";
  }

}

Create JDBC Repository

Let’s create a repository to interact with Tutorials from the database.

In repository package, create TutorialRepository interface that provides abstract methods:

for CRUD Operations: save, findById, findAll, update, deleteById, deleteAll.
custom finder methods: findByPublished, findByTitleContaining.

repository/TutorialRepository.java

package com.bezkoder.spring.jdbc.repository;

import java.util.List;

import com.bezkoder.spring.jdbc.model.Tutorial;

public interface TutorialRepository {
  int save(Tutorial book);

  int update(Tutorial book);

  Tutorial findById(Long id);

  int deleteById(Long id);

  List<Tutorial> findAll();

  List<Tutorial> findByPublished(boolean published);

  List<Tutorial> findByTitleContaining(String title);

  int deleteAll();
}

We continue to define JdbcTutorialRepository which implements TutorialRepository. It uses JdbcTemplate object for executing SQL queries or updates to interact with Database.

repository/JdbcTutorialRepository.java

package com.bezkoder.spring.jdbc.repository;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.dao.IncorrectResultSizeDataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

import com.bezkoder.spring.jdbc.model.Tutorial;

@Repository
public class JdbcTutorialRepository implements TutorialRepository {

  @Autowired
  private JdbcTemplate jdbcTemplate;

  @Override
  public int save(Tutorial tutorial) {
    return jdbcTemplate.update("INSERT INTO tutorials (title, description, published) VALUES(?,?,?)",
        new Object[] { tutorial.getTitle(), tutorial.getDescription(), tutorial.isPublished() });
  }

  @Override
  public int update(Tutorial tutorial) {
    return jdbcTemplate.update("UPDATE tutorials SET title=?, description=?, published=? WHERE id=?",
        new Object[] { tutorial.getTitle(), tutorial.getDescription(), tutorial.isPublished(), tutorial.getId() });
  }

  @Override
  public Tutorial findById(Long id) {
    try {
      Tutorial tutorial = jdbcTemplate.queryForObject("SELECT * FROM tutorials WHERE id=?",
          BeanPropertyRowMapper.newInstance(Tutorial.class), id);

      return tutorial;
    } catch (IncorrectResultSizeDataAccessException e) {
      return null;
    }
  }

  @Override
  public int deleteById(Long id) {
    return jdbcTemplate.update("DELETE FROM tutorials WHERE id=?", id);
  }

  @Override
  public List<Tutorial> findAll() {
    return jdbcTemplate.query("SELECT * from tutorials", BeanPropertyRowMapper.newInstance(Tutorial.class));
  }

  @Override
  public List<Tutorial> findByPublished(boolean published) {
    return jdbcTemplate.query("SELECT * from tutorials WHERE published=?",
        BeanPropertyRowMapper.newInstance(Tutorial.class), published);
  }

  @Override
  public List<Tutorial> findByTitleContaining(String title) {
    String q = "SELECT * from tutorials WHERE title ILIKE '%" + title + "%'";

    return jdbcTemplate.query(q, BeanPropertyRowMapper.newInstance(Tutorial.class));
  }

  @Override
  public int deleteAll() {
    return jdbcTemplate.update("DELETE from tutorials");
  }
}

– JDBCTemplate implements JdbcOperations which provides useful methods: execute(), query(), update(), queryForObject()…
– BeanPropertyRowMapper implements RowMapper that converts a table row into a new instance of the specified mapped target class (Tutorial).
– Tutorial class must be a top-level class and have a default constructor (no-argument).

Create Spring Rest APIs Controller

Finally, we create a controller that provides APIs for creating, retrieving, updating, deleting and finding Tutorials.

controller/TutorialController.java

package com.bezkoder.spring.jdbc.controller;

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.CrossOrigin;
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.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import com.bezkoder.spring.jdbc.model.Tutorial;
import com.bezkoder.spring.jdbc.repository.TutorialRepository;

@CrossOrigin(origins = "http://localhost:8081")
@RestController
@RequestMapping("/api")
public class TutorialController {

  @Autowired
  TutorialRepository tutorialRepository;

  @GetMapping("/tutorials")
  public ResponseEntity<List<Tutorial>> getAllTutorials(@RequestParam(required = false) String title) {
    try {
      List<Tutorial> tutorials = new ArrayList<Tutorial>();

      if (title == null)
        tutorialRepository.findAll().forEach(tutorials::add);
      else
        tutorialRepository.findByTitleContaining(title).forEach(tutorials::add);

      if (tutorials.isEmpty()) {
        return new ResponseEntity<>(HttpStatus.NO_CONTENT);
      }

      return new ResponseEntity<>(tutorials, HttpStatus.OK);
    } catch (Exception e) {
      return new ResponseEntity<>(null, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }

  @GetMapping("/tutorials/{id}")
  public ResponseEntity<Tutorial> getTutorialById(@PathVariable("id") long id) {
    Tutorial tutorial = tutorialRepository.findById(id);

    if (tutorial != null) {
      return new ResponseEntity<>(tutorial, HttpStatus.OK);
    } else {
      return new ResponseEntity<>(HttpStatus.NOT_FOUND);
    }
  }

  @PostMapping("/tutorials")
  public ResponseEntity<String> createTutorial(@RequestBody Tutorial tutorial) {
    try {
      tutorialRepository.save(new Tutorial(tutorial.getTitle(), tutorial.getDescription(), false));
      return new ResponseEntity<>("Tutorial was created successfully.", HttpStatus.CREATED);
    } catch (Exception e) {
      return new ResponseEntity<>(null, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }

  @PutMapping("/tutorials/{id}")
  public ResponseEntity<String> updateTutorial(@PathVariable("id") long id, @RequestBody Tutorial tutorial) {
    Tutorial _tutorial = tutorialRepository.findById(id);

    if (_tutorial != null) {
      _tutorial.setId(id);
      _tutorial.setTitle(tutorial.getTitle());
      _tutorial.setDescription(tutorial.getDescription());
      _tutorial.setPublished(tutorial.isPublished());

      tutorialRepository.update(_tutorial);
      return new ResponseEntity<>("Tutorial was updated successfully.", HttpStatus.OK);
    } else {
      return new ResponseEntity<>("Cannot find Tutorial with id=" + id, HttpStatus.NOT_FOUND);
    }
  }

  @DeleteMapping("/tutorials/{id}")
  public ResponseEntity<String> deleteTutorial(@PathVariable("id") long id) {
    try {
      int result = tutorialRepository.deleteById(id);
      if (result == 0) {
        return new ResponseEntity<>("Cannot find Tutorial with id=" + id, HttpStatus.OK);
      }
      return new ResponseEntity<>("Tutorial was deleted successfully.", HttpStatus.OK);
    } catch (Exception e) {
      return new ResponseEntity<>("Cannot delete tutorial.", HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }

  @DeleteMapping("/tutorials")
  public ResponseEntity<String> deleteAllTutorials() {
    try {
      int numRows = tutorialRepository.deleteAll();
      return new ResponseEntity<>("Deleted " + numRows + " Tutorial(s) successfully.", HttpStatus.OK);
    } catch (Exception e) {
      return new ResponseEntity<>("Cannot delete tutorials.", HttpStatus.INTERNAL_SERVER_ERROR);
    }

  }

  @GetMapping("/tutorials/published")
  public ResponseEntity<List<Tutorial>> findByPublished() {
    try {
      List<Tutorial> tutorials = tutorialRepository.findByPublished(true);

      if (tutorials.isEmpty()) {
        return new ResponseEntity<>(HttpStatus.NO_CONTENT);
      }
      return new ResponseEntity<>(tutorials, HttpStatus.OK);
    } catch (Exception e) {
      return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }

}

– @CrossOrigin is for configuring allowed origins.
– @RestController annotation is used to define a controller and to indicate that the return value of the methods should be be bound to the web response body.
– @RequestMapping("/api") declares that all Apis’ url in the controller will start with /api.
– We use @Autowired to inject TutorialRepository bean to local variable.

Run & Check

Run Spring Boot application with command: mvn spring-boot:run.

Let’s open H2 console with url: http://localhost:8080/h2-ui:

– For In-memory database:

– For on Disk database:

Click on Connect button, then check H2 database, you can see things like this.

Inside SQL Statement, write SQL script to create tutorials table:

CREATE TABLE tutorials
(
    id BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT,
    title VARCHAR(255),
    description VARCHAR(255),
    published NUMBER(1)
);

Create some Tutorials:

H2 database tutorials table after that:

Update some Tutorials:

The table data is changed:

Retrieve all Tutorials:

Retrieve a Tutorial by Id:

Find all published Tutorials:

Find all Tutorials which title contains string ‘jdbc’:

Delete a Tutorial:

Delete all Tutorials:

Database table is clean now:

You can also test this Spring Boot App with Client in one of these posts:

Conclusion

Today we’ve built a CRUD Rest API using Spring Boot, Spring Data JDBCTemplate working with H2 Database example.

You can handle Exception for this Rest APIs is necessary:
– Spring Boot @ControllerAdvice & @ExceptionHandler example
– @RestControllerAdvice example in Spring Boot

Or Unit Test:
Spring Boot – Rest Controller Unit Test with @WebMvcTest

Happy learning! See you again.

Source Code

You can find the complete source code for this tutorial on Github.

You will also see that JpaRepository supports a great way to make CRUD operations and custom finder methods without need of boilerplate code. Kindly visit:
Spring Boot JPA + H2 example: Build a CRUD Rest APIs

Documentation: Spring Boot + Swagger 3 example (with OpenAPI 3)

Spring Boot JdbcTemplate example: CRUD Rest API

Overview of Spring Boot JdbcTemplate CRUD example

Technology

Project Structure

Create & Setup Spring Boot project

Configure Spring Data and H2 database

Define Data Model

Create JDBC Repository

Create Spring Rest APIs Controller

Run & Check

Conclusion

Further Reading

Source Code

One thought to “Spring Boot JdbcTemplate example: CRUD Rest API”

Tools

Overview of Spring Boot JdbcTemplate CRUD example

Technology

Project Structure

Create & Setup Spring Boot project

Configure Spring Data and H2 database

Define Data Model

Create JDBC Repository

Create Spring Rest APIs Controller

Run & Check

Conclusion

Further Reading

Source Code

One thought to “Spring Boot JdbcTemplate example: CRUD Rest API”

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