Spring Reference Manual

A walkthrough of all Spring Framework projects and concepts essential for developing the backend of enterprise web applications.

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Table of Contents

1. Spring Core
2. Spring JDBC
3. Spring Boot
4. Spring Data JPA - Deep Dive
5. Spring Security

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1. Spring Core

1.1. IoC and DI Basics

• Tight and Loose Coupling
• XML Configuration for IoC and DI
• Java Configuration for IoC and DI
• Annotations and Hybrid Configurations for IoC and DI
• Bean Scopes and Scope Combinations
• Lazy Initialization
• Properties
• XML Value Injection (Primitives and Non-primitives)
• Spring Profiles

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2. Spring JDBC

2.1. Introduction

• Spring JDBC Introduction
• Configuring XML for Database Connection
• Configuring Java Config File for Database Connection (Alternative to XML Config)
• Insert, Update, and Delete Operations with JdbcTemplate
• Configuring RowMapper Implementation Class for Select Operations
• Single-Object Select Queries and Multi-Object Select Queries with JdbcTemplate and RowMapper

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3. Spring Boot

3.1. Introduction to Spring Boot

• Understanding Spring Boot Project Structure
• Customizing the Application Banner
• Testing Spring Core Features in a Spring Boot Application
• Reading System and Custom Properties with the Environment Interface

3.2. Introduction to Spring REST Architecture

• Working with the Controller Layer and HTTP Requests/Responses
• Using Path Parameters and Query Parameters in Routing

3.3. Spring Data JPA Introduction

• Defining Application Properties with a YAML Data Serialization File
• Configuring PostgreSQL for Database Operations
• Creating Entity Classes and Mapping Fields with Database Schemas
• Using JpaRepository for Persistence Layer Methods
• Performing CRUD Operations with JPA
• Defining Custom Search Functions in the Repository with JPA Query Methods
• Defining Entity Relationships with Hibernate Mappings
• Assigning Secondary/Child Entities to Primary/Parent Entities via API Requests
• Resolving Parent-Child Serialization Issues on Child's GET Requests

3.4. Spring DTO Pattern, Data Validation, and Unit Testing

• Customizing REST API Requests and Responses with the DTO Pattern
• Using Java Records (JDK 14+) for DTO Files Creation
• Refactoring Code to Move Business Logic to the Service Layer
• Performing Basic Data Validation for API Request Objects
• Handling Bad Request Exceptions After Validation
• Introduction to Spring Testing with JUnit 5
• Unit Testing Basic Methods of Mapper Classes
• Achieving Test Isolation with Mockito by Mocking External Beans
• Testing Service Layer Methods with Mockito

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4. Spring Data JPA - Deep Dive

Advanced JPA Concepts

• Using Lombok Annotations to Reduce Boilerplate Code
• Understanding Primary Key ID Generation Strategies
• Exploring the Hibernate Entity Lifecycle
• Testing Repository Methods with the CommandLineRunner Bean
• Unidirectional vs. Bidirectional Entity Mappings
• Advanced Hibernate Entity-Relationship Mappings

Inheritance and Embedded Entities

• Using @MappedSuperclass for Common Entities
• Exploring JPA-Hibernate Entity Inheritance Strategies
• Creating Composite Primary Keys with @Embeddable and @EmbeddedId
• Resolving Multiple Inheritance Issues with Embedded Entities

Custom Queries and Specifications

• Defining Custom Queries with the @Query Annotation
• Creating Optimized Queries with Named Queries
• Implementing Specifications for Dynamic and Type-Safe Queries

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5. Spring Security

5.1. Setting up

• Setting up a Spring Boot Project with Dependencies for Spring Security
• Understanding the Basic Auth Header and Its Encoding
• Creating an In-Memory User for Authentication

5.2. Managing Users

• Enabling User Authentication via Database User Entries
• Configuring UserDetails, UserDetailsService, and WebConfig Classes for Authentication
• Managing User Authorities with the GrantedAuthority Interface

5.3. Implementing Key-Based Custom Authentication

• Defining SecurityFilterChain bean in configuration class
• Creating Custom Authentication Filter class as a part of Filter Chain
• Writing implementations of AuthenticationManager and AuthenticationProvider for our custom filter
• Understanding the workflow of Authentication process inside Authentication Filter
• Testing and Debugging the Key-based Custom Authentication application

5.4. Multiple Authentication Providers

• Overview of Chaining Default Filters with Custom Filters
• Chaining multiple filters and availing multiple authentication methods for an user
• addFilterBefore() vs addFilterAfter() vs addFilterAt()

5.5. Endpoint Authorization

• Understanding endpoint authorization associated methods
• Testing the chain of different combinations of matcher methods with authorization rules
• Use of different authorization rules
• Introduction to requestMatchers() matcher method (Spring Security 5.8+)

5.6. More with Endpoint Authorization (Matcher method)

• Protecting various endpoints using requestMatchers()
• Securing endpoints under the same route prefix group
• Configuring matchers for the same endpoint with different HTTP methods

5.7. Method Authorization

• Securing methods in controller, service, and repository classes using Method-level authorization
• Overview of @EnableMethodSecurity in the WebSecurityConfig class
• Utilizing @PreAuthorize and @PostAuthorize to specify authorization rules for methods
• Using @PreFilter and @PostFilter to filter incoming and outgoing collection object requests