Spring Boot 3.0 Crash Course: Mastering Spring Boot, from Application Development to Advanced Security, Data Access, Integration and Deployment

Spring Boot 3.0 Crash Course

Mastering Spring Boot, from Application Development to Advanced Security, Data Access, Integration and Deployment

Kit Harrington

Preface

This Spring Boot 3.0 Crash Course will teach you all you need to know to create powerful Spring applications with the latest version of the framework. You will be able to create any feature that an application may require because this book covers everything from the fundamentals to advanced features.

First things first: get your development environment ready and build your very first Spring Boot App. Data access, security, configuration, and testing are some of the more advanced subjects you'll cover as you go along. This crash course will teach you how to create RESTful services, use Spring Data JPA to integrate different types of data, and work with properties and YAML files to oversee configurations. You practice to manage application properties, get into the application of annotations, and master the Spring MVC architecture. It will teach you to manage form submissions, validate user input, and construct dynamic web pages using Thymeleaf templates. The book also covers topics like integrating front-end frameworks, handling errors, and deploying applications to cloud platforms and Kubernetes.

Issues with configuring URL authorization, implementing JWT authentication, and integrating with OAuth2 and OpenID Connect are some of the critical problems that are being solved in this book. Methods for troubleshooting auto-configuration issues, managing environment variables in Docker, and making use of performance testing tools such as JMeter are all topics that will be covered. Additionally, the book delves into the topic of how to integrate with Active Directory and LDAP for centralized user management and authentication.

By the time you finish this book, you will know everything there is to know about Spring Boot application development, security, and deployment, so you can confidently take on real-world projects.

In this book you will learn how to:

Discover the ins and outs of efficiently configuring a Spring Boot 3.0 development environment.

Integrate various data sources and construct strong RESTful services with the help of Spring Data JPA.

Get to know Spring Boot's properties and YAML files to set up customizable apps.

Use Spring Security and JWT tokens to implement secure authorization and authentication.

Use Thymeleaf templates to build interactive websites and easily handle form submissions.

Use Kubernetes and cloud platforms to effortlessly deploy Spring Boot applications.

Make your apps more up-to-date and responsive by incorporating front-end frameworks such as Angular and React.

Put thorough error handling strategies into your applications and handle errors gracefully.

Use Docker to manage environment variables and JMeter to optimize application performance.

Prologue

Thank you for choosing our Spring Boot 3.0 Crash Course. Hi, I'm Kit Harrington, and I'm really excited to show you how to use Spring Boot 3.0. Allow me to begin by relating a tale that exemplifies why this book is so important.

A fast-growing tech startup had me as their project manager a few years back. The success of the business hinged on creating a safe, scalable, and reliable app that could manage thousands of users with ease. These lofty expectations were squarely on my shoulders as lead developer. The complexity of integrating different technologies, guaranteeing security, and optimizing performance was a challenge for me, even though I have a lot of experience in this area. I started using Spring Boot as my primary tool at that point. An easier way to build apps using the Spring framework was made available by Spring Boot. I was able to focus on creating effective code because it made setting everything up and running much easier. Thanks to Spring Boot's robust capabilities, we were able to build and deploy features at an incredible pace. Mastering Spring Boot, though, necessitated familiarity with its foundational concepts, recommended practices, and more complex features.

That experience is the foundation of this book. I hope that by sharing what I've learned and the solutions I've found, you'll be able to build your Spring Boot applications with ease and confidence. In this book, I'll show you how to build an app using Spring Boot from the ground up, including all the necessary features and making sure it's secure, scalable, and fast. You may find at times repetition of steps while demonstrating practical examples, so apology in advance but the intention is to ensure you dont get stuck in the middle of coding the application.

In this first step, you will build your first Spring Boot app and configure your development environment. The course will teach you the ins and outs of dependency management, application configuration via properties and YAML files, and more. Annotations, data source integration with Spring Data JPA, and RESTful service construction are some of the more advanced topics that we will cover as we go along. I will demonstrate how to incorporate Spring Security authentication and authorization, two essential components of any application. In this lesson, you will find out how to secure your application from intruders by configuring basic authentication, URL authorization, and JWT authentication.

Also covered will be the basics of working with Thymeleaf templates to build dynamic web pages, accept and process form submissions, and check user input. Learn the ins and outs of integrating popular front-end frameworks such as Angular and React to create cutting-edge, mobile-friendly apps. I will show you how to package your app, make Docker images, and deploy them to cloud platforms and Kubernetes—all of which are essential steps in the development process. Managing environment variables and achieving zero downtime during deployments are topics you'll cover in this course. Using JMeter for performance testing, I will demonstrate how to optimize performance, which is essential for deliver

ing an excellent user experience. You will gain knowledge on how to locate performance issues and enhance your application to its full potential.

With the knowledge and skills, you gain from this book, you will be able to confidently construct applications that are strong, secure, and perform well. So that you can put what you learn into practice right away, I want to equip you with practical knowledge and real-world examples.

Come on, let's start making awesome Spring Boot apps!

Copyright © 2024 by GitforGits

All rights reserved. This book is protected under copyright laws and no part of it may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without the prior written permission of the publisher. Any unauthorized reproduction, distribution, or transmission of this work may result in civil and criminal penalties and will be dealt with in the respective jurisdiction at anywhere in India, in accordance with the applicable copyright laws.

Published by: GitforGits

Publisher: Sonal Dhandre

www.gitforgits.com

[email protected]

Printed in India

First Printing: July 2024

Cover Design by: Kitten Publishing

For permission to use material from this book, please contact GitforGits at [email protected].

Content

Preface

GitforGits

Acknowledgement

Chapter 1: Up and Running with Spring Boot

Chapter Overview

What is Spring Boot?

Emergence of Spring Boot

Relation to Spring Framework

Recent Version

Applications, Programs, and APIs

Key Features of Spring Boot

Auto-configuration

Spring Boot Starters

Embedded Servers

Production-Ready Features

Externalized Configuration

Spring Boot CLI

DevTools

Spring Initializr

Actuator

Spring Boot DevTools

Simplified Dependency Management

Simplified Testing

Application Metrics and Health Checks

Security Integration

Integration with Other Spring Projects

Reactive Programming Support

GraalVM Native Image Support

Setting up Development Environment

Installing JDK

Installing IDE

Installing Apache Maven

Installing Spring Boot CLI

Creating Spring Boot Project

Configuring IDE

Running first Spring Boot App

Exploring Project Structure

Adding Dependencies

Configuring Application Properties

Spring Boot DevTools

Spring Boot CLI

Creating First Spring Boot Application

Setting up the Project

Creating Main Application Class

Creating a REST Controller

Running the Application

Understanding Auto-configuration

Adding Dependency Injection

Exploring Application Properties

Understanding Spring Boot Dependencies

Spring Boot Starters

Maven

Dependency Management

Adding Custom Dependencies

Using Spring Boot DevTools

Dependency Exclusions

Resolving Dependency Conflicts

Using Bill of Materials (BOM)

Upgrading Dependencies

Annotations Overview

Core Annotations

Stereotype Annotations

Configuration and Bean Annotations

Dependency Injection Annotations

Spring MVC Annotations

Data Access Annotations

Testing Annotations

Actuator Annotations

Overview of Spring Boot CLI

Installing Spring Boot CLI

Creating Simple Web App with CLI

Using Spring Boot CLI for Dependency Management

Packaging Applications with Spring Boot CLI

Spring Boot CLI for Existing Projects

Prototyping

Spring Boot CLI Configuration

Spring Boot CLI with Spring Initializr

Spring Boot CLI with Groovy Templates

Summary

Chapter 2: Building First Spring Boot App

Chapter Overview

Creating a Basic RESTful Service

Main Application Class

Creating a REST Controller

Running the Application

Expanding the REST Controller

Handling GET and POST Requests

Implementing GET Requests

Implementing POST Requests

Handling PUT and DELETE Requests

Implementing PUT Requests

Implementing DELETE Requests

Using Path Variables and Request Parameters

Using Path Variables

Using Request Parameters

Using Message Converters

Built-in Message Converters

Sample Program: Working of Message Converters

Spring MVC Architecture Overview

Understanding Spring MVC

Spring MVC Core Components

Sample Program: Inner Workings of MVC Components

Error Handling in Spring Boot

Built-in Error Handling

Customizing Error Responses

Handling Validation Errors

Summary

Chapter 3: Configuration and Properties

Chapter Overview

Spring Boot Configuration Overview

Application Properties

YAML for Structured Configuration

Profiles for Environment-Specific Configurations

Externalizing and Securing Configuration

Using Application Properties

Basic Configuration

Grouping Related Properties

Configuring Logging

Profiles in Application Properties

External Configuration

Using Application Properties

Configuration with YAML Files

Setting up YAML Configuration

Advantages of YAML

Profiles with YAML

Accessing YAML Properties

Profiles and Environment Specific Configurations

Defining Profiles

Activating Profiles

Using Profile-Specific Beans

Combining Profiles

Profile-Specific Configuration Properties

Accessing Profile Information

Externalizing Configuration

Using Environment Variables

Centralized Configuration with Spring Cloud Config

@Value and @ConfigurationProperties

Using @Value

Using @ConfigurationProperties

Binding Complex Nested Properties

Validation with @ConfigurationProperties

Type-Safe Configuration Properties

Setting up Type-Safe Configuration Properties

Advanced Type-Safe Configuration

Reloading Configuration Properties at Runtime

Using Spring Cloud Context

Using Spring Cloud Bus

Handling Configuration Reloads

Monitoring Configuration Changes

Summary

Chapter 4: Spring Boot Packaging and Deployment

Chapter Overview

Packaging a Spring Boot Application

Understanding Executable JAR Files

Understanding Executable WAR Files

Process of Packaging

Automating Packaging Process

Integrating Packaging with CI/CD Pipelines

Creating Executable JAR and WAR Files

Creating an Executable JAR File

Creating an Executable WAR File

Deploying to Tomcat

Install Tomcat and Copy WAR File

Start the Tomcat Server

Verifying Deployment

Hot Deployment and Redeployment

Managing Tomcat Deployments

Automating Deployment with CI/CD

Deploying to Jetty and Undertow

Why Jetty?

Jetty Deployment

Undertow Overview

Undertow Deployment

Deploying to Docker

Deploying Spring Boot Application

Deploying to AWS

Setup EC2 Instance

Install Java on EC2 Instance

Transfer Application JAR/WAR File to EC2

Run Application

Using AWS Elastic Beanstalk

Using AWS Elastic Container Service

Running Apps in Kubernetes

Setting up Kubernetes

Deploying Application to Kubernetes

Creating Spring Boot Docker Images

Workflow for Docker Images

Sample Program: Creation of Docker Images

Summary

Chapter 5: Spring Boot Auto-configuration

Chapter Overview

Understanding Auto-configuration

Auto-configuration Overview

Key Components of Auto-configuration

Sample Program: Auto-configuration using JPA and H2

Customizing Auto-configuration

Overriding Default Beans

Conditional Beans and Customization

Customizing Configuration with @ConfigurationProperties

Customizing Auto-configuration with Custom Annotations

Exploring Spring Boot Starter POMs

Using Conditional Beans

Common Conditional Annotations

Sample Program: Using Conditional Annotations

Writing Custom Auto-configuration

Custom Auto-configuration Workflow

Sample Program: Writing Custom Auto-configuration

Exploring Starter POMs

Common Spring Boot Starter POMs

Sample Program: Using Starter POMs

Summary

Chapter 6: Data Access with Spring Data JPA

Chapter Overview

Introduction to Spring Data JPA

Key Features of Spring Data JPA

Up and Running with Spring Data JPA

Configuring Data Source

Adding Dependencies

Defining Data Source Properties

Creating JPA Entities

Creating Repository Interfaces

Implementing Service Layer

Creating Controller Layer

JPA Entities and Relationships

Defining JPA Entities

One-to-One Relationship

One-to-Many and Many-to-One Relationships

Many-to-Many Relationship

Query Methods and Custom Queries

Defining Query Methods

Writing Custom Queries with @Query

Using JPA Criteria API

Why Criteria API?

Sample Program: Using JPA Criteria API

Paging and Sorting with Spring Data JPA

Brief Overview

Setting up Paging and Sorting

Handling Transactions in Spring Boot

Enabling Transaction Management

Using @Transactional Annotation

Transaction Scenarios

Additional Transaction Management

Integrating with Liquibase and Flyway for Database Migrations

Configuring Liquibase

Configuring Flyway

Performing Database Migrations

Sample Program: Combining Liquibase and Flyway

Summary

Chapter 7: Building Web Applications

Chapter Overview

Introduction to Spring MVC

Model-View-Controller Architecture

Spring MVC Components

Sample Program: Creating a User Management System using Spring MVC

Creating Controllers and Views

Creating Controllers

Creating Views

Using Thymeleaf Templates

Setting up Thymeleaf

Basic Syntax and Expressions

Creating a User Form with Validation

Implementing User Details View

Adding a CSS File for Styling

Updating the Application to Serve Static Content

Handling Form Submissions

Form Binding with Thymeleaf

Controller Method for Handling Form Submissions

Adding Validation Constraints

Handling Form Submission and Validation Errors

Validating User Input

Adding Validation Constraints to the Entity

Updating Controller to Handle Validation

Updating Form to Display Validation Errors

Utilizing WebSockets

Brief Overview

Configuring WebSockets

File Upload and Download Handling

Configuring File Uploads

Creating a File Upload Controller

Handling File Downloads

Integrating Front-End Frameworks

Integrating React with Spring Boot

Integrating Angular with Spring Boot

Summary

Chapter 8: Testing Spring Boot Applications

Chapter Overview

Getting Started with Testing

Background

Types of Testing

Unit Testing with JUnit and Mockito

Setting up JUnit and Mockito

Example 1: Unit Testing a Service Layer

Example 2: Unit Testing a Controller Layer

Conduct Slice Testing for Layer-Specific Tests

Understanding Layer-Specific Tests

Slice Testing for the Data Layer

Slice Testing for the Web Layer

MockMVC for Web Layer Testing

Introduction to MockMVC

Setting up MockMVC

Sample Program: Using MockMVC

Testing Data Repositories

Types of Data Repositories

Sample Program: Testing Data Repositories

Sample Program: Testing a Custom Repository Method

Testing with TestContainers

Setting up TestContainers

Writing Integration Tests with TestContainers

Performance Testing with JMeter

Introduction to JMeter

Setting up JMeter

Sample Test Plan

Summary

Chapter 9: Security in Spring Boot

Chapter Overview

Explore Spring Security

Introduction to Spring Security

Core Components of Spring Security

Configuring Basic Authentication

Setting up Spring Security

Customizing Basic Authentication

Configuring URL Authorization

Setting up URL Authorization

Customizing Access Denied Handling

Testing the Custom Access Denied Handler

JWT, OAuth and OpenID Connect

Setting up JWT Authentication

Setting up OAuth and OpenID Connect

Integrating with LDAP and Active Directory

Setting up LDAP Integration

Integrating with Active Directory

Summary

Index

Epilogue

GitforGits

Prerequisites

Whether you're a seasoned developer or just getting started, this book introduces you to geete comfortable with Spring Boot and take the most benefits of its tools to create high-quality apps quickly. All you need is to be just a basic programming experience with any of the languages to get started with.

Codes Usage

Are you in need of some helpful code examples to assist you in your programming and documentation? Look no further! Our book offers a wealth of supplemental material, including code examples and exercises.

Not only is this book here to aid you in getting your job done, but you have our permission to use the example code in your programs and documentation. However, please note that if you are reproducing a significant portion of the code, we do require you to contact us for permission.

But don't worry, using several chunks of code from this book in your program or answering a question by citing our book and quoting example code does not require permission. But if you do choose to give credit, an attribution typically includes the title, author, publisher, and ISBN. For example, Spring Boot 3.0 Crash Course by Kit Harrington.

If you are unsure whether your intended use of the code examples falls under fair use or the permissions outlined above, please do not hesitate to reach out to us at [email protected]. 

We are happy to assist and clarify any concerns.

Chapter 1: Up and Running with Spring Boot

Chapter Overview

Let us start with our first chapter, Up and Running with Spring Boot, which will serve as the foundation for your skill-building transition into Spring Boot. This chapter will walk you through the core concepts and essential features that make Spring Boot a powerful framework for developing robust applications. You'll start by learning about Spring Boot and how it evolved from the Spring Framework, which will help you understand why it's so popular among developers today.

As you progress, you'll discover the key features that set Spring Boot apart from other frameworks. Some of its features include an opinionated approach to configuration, the ability to build standalone apps, and the ability to integrate with different technologies seamlessly. Understanding these features will help you appreciate the efficiency and simplicity that Spring Boot adds to application development. You will then proceed to set up your development environment, ensuring that all required tools are installed and configured. This includes configuring your IDE, JDK, and other essential components. Following that, you will create your first Spring Boot application, giving you hands-on experience with the framework's capabilities. This practical approach will be supplemented by exploring Spring Boot dependencies and starter projects, which make dependency management and project setup easier.

Finally, the chapter will go over Spring Boot annotations and the Spring Boot CLI. By the end of this chapter, you will have a solid understanding of Spring Boot, allowing you to delve deeper into its advanced features and capabilities in the following chapters.

What is Spring Boot?

Spring Boot has gained significant traction among developers for its ability to simplify the creation of stand-alone, production-grade Spring-based applications. It has become synonymous with rapid application development, offering a set of tools and features that streamline the entire development process. The modern developer community appreciates Spring Boot for its minimal setup, reduced boilerplate code, and the seamless integration it provides with other technologies.

Emergence of Spring Boot

Spring Boot emerged as an enhancement to the Spring Framework, addressing some of the complexities and configuration challenges developers faced with traditional Spring applications. The Spring Framework, introduced in 2003, brought a revolutionary approach to Java development by promoting loose coupling through dependency injection and aspect-oriented programming. However, as the Spring ecosystem grew, configuring and deploying Spring applications became increasingly intricate. This is where Spring Boot comes into play.

Spring Boot was introduced to tackle these challenges by providing a convention-over-configuration approach. It simplifies the development process by offering default configurations and sensible defaults, which can be customized as needed. This allows developers to focus more on writing business logic rather than dealing with complex configurations.

Relation to Spring Framework

Spring Boot is essentially built on top of the Spring Framework, leveraging its core principles and components while abstracting much of the boilerplate configuration. This relationship ensures that Spring Boot applications inherit the robust and flexible nature of the Spring Framework but with added ease of use and productivity enhancements.

At its core, Spring Boot provides:

●       Pre-configured dependencies for various functionalities, reducing the need for manual