spring-boot-scaffolding

Overview

Reference guide for creating a fresh Spring Boot project with modern best practices. Used during implementation phase when the target project needs to be scaffolded.

User Input

You MUST consider the user input before proceeding (if not empty).

When to Use

• Mode: REWRITE only
• Phase: Implementation — when a task requires creating the target project
• Prerequisites: Plan and tasks defined

Technology Stack Selection

Common Target Stacks

Source Stack	Recommended Target	JDK	Key Changes
Struts 2	Spring Boot 3.x	17+	MVC framework
JSF 2.x	Spring Boot 3.x	17+	REST or Thymeleaf
EJB 3.x	Spring Boot 3.x	17+	DI framework
Java EE 7/8	Jakarta EE 10 or Spring Boot 3.x	17+	Namespace changes
Legacy Spring	Spring Boot 3.x	17+	Boot conventions

JDK Version Guidelines

Target JDK	LTS Until	Features
JDK 17	2029+	Records, Sealed classes, Pattern matching
JDK 21	2031+	Virtual threads, Sequenced collections

Recommendation: Use JDK 21 for new projects unless specific compatibility requirements exist.

Scaffolding Process

Step 1: Define Target Configuration

Create FEATURE_DIR/target-config.yaml:

target_configuration:
  project_name: "[NEW_PROJECT_NAME]"
  
  jdk:
    version: 21
    vendor: "Eclipse Temurin"
  
  framework:
    name: "Spring Boot"
    version: "3.2.x"
  
  build_tool:
    name: "Maven"
    version: "3.9.x"
  
  project_structure:
    type: "multi-module"  # or single-module
    modules:
      - name: "api"
        description: "REST API controllers"
      - name: "service"
        description: "Business logic services"
      - name: "persistence"
        description: "Data access layer"
      - name: "common"
        description: "Shared utilities and DTOs"
  
  dependencies:
    - "spring-boot-starter-web"
    - "spring-boot-starter-data-jpa"
    - "spring-boot-starter-validation"
    - "spring-boot-starter-test"
    - "lombok"
    - "mapstruct"
  
  database:
    type: "PostgreSQL"
    migration_tool: "Flyway"

Step 2: Generate Project Structure

Option A: Use Spring Initializr (Recommended)

curl https://start.spring.io/starter.zip \
  -d type=maven-project \
  -d language=java \
  -d bootVersion=3.2.0 \
  -d baseDir=[PROJECT_NAME] \
  -d groupId=com.example \
  -d artifactId=[PROJECT_NAME] \
  -d name=[PROJECT_NAME] \
  -d packageName=com.example.[PACKAGE] \
  -d javaVersion=21 \
  -d dependencies=web,data-jpa,validation,lombok \
  -o [PROJECT_NAME].zip

unzip [PROJECT_NAME].zip

Option B: Manual Creation

[PROJECT_NAME]/
├── pom.xml                          # Parent POM
├── api/
│   ├── pom.xml
│   └── src/main/java/com/example/api/controller/
├── service/
│   ├── pom.xml
│   └── src/main/java/com/example/service/
├── persistence/
│   ├── pom.xml
│   └── src/main/java/com/example/persistence/
│       ├── entity/
│       └── repository/
├── common/
│   ├── pom.xml
│   └── src/main/java/com/example/common/
│       ├── dto/
│       └── util/
└── application/
    ├── pom.xml
    └── src/main/java/com/example/Application.java

Step 3: Configure Base Files

pom.xml (Parent)

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
                             http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.0</version>
        <relativePath/>
    </parent>
    
    <groupId>com.example</groupId>
    <artifactId>[PROJECT_NAME]-parent</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <packaging>pom</packaging>
    
    <properties>
        <java.version>21</java.version>
        <maven.compiler.source>21</maven.compiler.source>
        <maven.compiler.target>21</maven.compiler.target>
    </properties>
    
    <modules>
        <module>common</module>
        <module>persistence</module>
        <module>service</module>
        <module>api</module>
        <module>application</module>
    </modules>
</project>

Application.java

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

application.yml

spring:
  application:
    name: [PROJECT_NAME]
  datasource:
    url: jdbc:postgresql://localhost:5432/[DB_NAME]
    username: ${DB_USERNAME}
    password: ${DB_PASSWORD}
    driver-class-name: org.postgresql.Driver
  jpa:
    hibernate:
      ddl-auto: validate
    open-in-view: false
  flyway:
    enabled: true
    locations: classpath:db/migration

server:
  port: 8080

logging:
  level:
    com.example: DEBUG
    org.springframework: INFO

logback-spring.xml

<configuration>
    <include resource="org/springframework/boot/logging/logback/defaults.xml"/>
    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>
    <root level="INFO">
        <appender-ref ref="CONSOLE"/>
    </root>
    <logger name="com.example" level="DEBUG"/>
</configuration>

GlobalExceptionHandler.java

package com.example.api.exception;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

@RestControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(Exception.class)
    public ResponseEntity<ErrorResponse> handleGenericException(Exception ex) {
        ErrorResponse error = new ErrorResponse(
            HttpStatus.INTERNAL_SERVER_ERROR.value(),
            "Internal server error",
            ex.getMessage()
        );
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(error);
    }
}

Step 4: Verify Scaffold

cd [PROJECT_NAME]
./mvnw clean compile
./mvnw test
./mvnw spring-boot:run
curl http://localhost:8080/actuator/health

Scaffold Checklist

• Project structure created
• Parent POM configured with correct versions
• All module POMs created with dependencies
• Application main class created
• application.yml configured
• Logging configured
• Global exception handler created
• Database migration folder created
• Build succeeds (mvn clean compile)
• Application starts (mvn spring-boot:run)

Output Artifacts

Artifact	Path	Purpose
Target Config	FEATURE_DIR/target-config.yaml	Target stack configuration
Project Root	[PROJECT_NAME]/	Scaffolded project