Springboot Demo

Table of Contents

• Introduction
• Overview
• Technical Stack
• Features
• User Guide
• Deployment Guide

Introduction

This is a Spring Boot application designed to demonstrate a layered architecture pattern in Java programming. The project uses a simple domain model to illustrate how responsibilities are separated across multiple layers to ensure loose coupling, maintainability, and scalability.

It was developed as a reference implementation of:

• Interlayer data flows
• DTO mapping
• Exception handling
• Application containerization with Docker

Overview

System Architecture

Class Diagram

Layers

Layer	Responsibility
Controller	Handles HTTP requests and responses
Service	Provides business logic
Repository	Handles database operations
Database	Persists structured data

Technical Stack

Technology	Explanation
Java 8
Spring Boot	Application framework
Spring Web	REST API
Spring Data JPA	ORM & database interaction
Hibernate	JPA implementation
Redis	Cache
Postgre SQL	Database
Maven	Dependency management
Docker	Containerization

Features

DTO Pattern

• Designated data transfer format from the frontend
• Separates internal entity from API contract

Exception Handling

• Global exception handler
• Custom exception format
• Standardized error response

User Guide

Build and Run

• Prerequisites

  • JDK 1.8
  • Maven 3.6.x or above
  • Redis 8.6-alpine
  • PostgreSQL 17

• Build Project

mvn clean install

• Build Project and skip tests

mvn clean install -Dmaven.test.skip

• Start Redis Service

  • Modify src/main/resources/application.properties

    • Change spring.redis.port to desired Redis port

  • For Windows systems

    • Run on WSL
    • Run Redis Docker image

• Start Application

mvn spring-boot:run

• Run Unit Test

mvn test

API Endpoints

Exposed port 8085

• GET /msg

  Returns a full list of messages

  Sample Response

  [
      {
          "id": 0,
          "data": [
              "object0",
              "object1",
              "object2"
          ],
          "info": "sample0"
      },
      {
          "id": 1,
          "data": [
              "object3",
              "object4"
          ],
          "info": "sample1"
      }
  ]

  Response Code

  • 200 OK
  • 500 Internal Server Error

• GET /msg/:id

  Fetches a single message by ID

  Sample Response

  {
      "id": 0,
      "data": [
          "object0",
          "object1",
          "object2"
      ],
      "info": "sample0"
  }

  Response Code

  • 200 OK
  • 400 Bad Request
  • 500 Internal Server Error

• POST /msg

  Creates a new message

  Sample Request

  {
      "id": 0,
      "data": [
          "object0",
          "object1",
          "object2"
      ],
      "info": "sample0"
  }

  Response Code

  • 201 Created
  • 500 Internal Server Error

• PUT /msg/:id

  Updates provided fields of an existing message

  Sample Request

  {
      "id": 0,
      "data": [
          "object0",
          "object1",
          "object2",
          "object5"
      ],
      "info": "sample0-modified"
  }

  Sample Response

  {
      "id": 0,
      "data": [
          "object0",
          "object1",
          "object2",
          "object5"
      ],
      "info": "sample0-modified"
  }

  Response Code

  • 200 OK
  • 400 Bad Request
  • 500 Internal Server Error

• DELETE /msg/:id

  Delete an existing message

  Response Code

  • 200 OK
  • 400 Bad Request
  • 500 Internal Server Error

• DELETE /msg

  Clears all messages

  Response Code

  • 200 OK
  • 500 Internal Server Error

Deployment Guide

Project Structure

src/main/java/SpringbootDemo
├── controller
│   └── MessageController
├── service
│   ├── IMessageService
│   └── MessageService
├── repository
│   └── MessageRepo
├── entity
│   ├── Message
│   └── dto/MessageDto
├── config
│   └── RedisCacheConfig
├── exception
│   ├── MessageException
│   ├── ErrorMessage
│   ├── ErrorResponse
│   └── GlobalExceptionHandler
└── SpringbootDemoApplication

Database Schema

JPA Entity Configuration

@Table(name="tb_msg")
@Entity
class Message {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column
    long id;

    @ElementCollection(targetClass = String.class, fetch = FetchType.EAGER)
    @CollectionTable(name = "tb_data", joinColumns = @JoinColumn(name = "msg_id"))
    @Column(nullable = false)
    List<String> data;

    @Column
    String info;
}

SQL Schema

CREATE TABLE tb_msg (
    id INT NOT NULL AUTO_INCREMENT,
    info VARCHAR(255),
    PRIMARY KEY (id)
);

CREATE TABLE tb_data (
    msg_id INT NOT NULL,
    data VARCHAR(255) NOT NULL,
    CONSTRAINT fk_msg
        FOREIGN KEY (msg_id)
        REFERENCES tb_msg(id)
        ON DELETE CASCADE
);

Docker Deployment

• Build Docker Image

  docker build -t spring-demo .
  

• Start Redis Container

  docker run -p 9000:6379 redis:8.6-alpine
  

• Run App Container

  docker run -p 8085:8085 spring-demo