maa-atk/SpringREST

Java Spring Development Notes

These are notes summarizing key concepts and annotations related to Java Spring development. It covers various topics such as Spring Core, Spring MVC, Spring Data Access, Spring Boot, and additional Spring features.

Table of Contents

• Introduction
• Spring Core
• Spring MVC
• Spring Data Access
• Spring Boot and Application Development
• Additional Spring Features
• Annotations
• Development with POJO Objects
• WAR File - Web Application Archive
• Dependency Injection
• Minimizing Boilerplate Code
• AOP - Aspect-Oriented Programming
• Data Access Layer
• JMS - Java Message Service
• Transactions
• Web Layer
• JMX - Java Management Extensions
• Test Layer
• Spring Bean Lifecycle

Introduction

• POJO Objects: Plain Old Java Objects used to represent structured data.
• WAR File: Web Application Archive, a file format for packaging web applications.
• Dependency Injection: Design pattern for achieving loose coupling between components.
• Minimize Boilerplate Code: Using helper classes and frameworks to reduce repetitive code.

Spring Core

• Inversion of Control (IoC) Container: Manages object creation and dependency injection.
• Bean Factory: Container for holding beans.
• Component Scanning: Automatically detects and registers beans based on annotations.
• Bean Scopes: Define the lifecycle and visibility of beans.
• Bean Lifecycle: Initialization and destruction phases of beans.

Spring MVC

• Controllers: Handle HTTP requests and generate responses.
• Request Mapping: Maps HTTP requests to specific handler methods or classes.
• Request Parameters: Handle query parameters and form data.
• Request Body: Bind the HTTP request body to a method parameter.
• Views and Templates: Render the UI using view technologies.
• Exception Handling: Customize exception handling using annotations.

Spring Data Access

• JPA (Java Persistence API): Specification for ORM in Java.
• Hibernate: ORM framework implementing JPA.
• Entity Class: Represents a mapped object in the database.
• JPQL (Java Persistence Query Language): Query language for JPA.
• Repository Pattern: Data access object (DAO) layer using Spring Data repositories.
• Transactions: Manage database transactions using annotations.

Spring Boot and Application Development

• Maven: Build automation tool for managing dependencies and project build processes.
• Spring Boot: Framework for simplifying Spring application development.
• Annotations: An overview of annotations used in Spring.

Additional Spring Features

• AOP (Aspect-Oriented Programming): Separating cross-cutting concerns from the main application logic.
• Spring Security: Authentication and authorization framework for securing applications.
• Spring Actuator: Monitoring and managing applications.
• Spring Testing: Unit testing and integration testing using Spring-specific features.
• JMS (Java Message Service): Messaging standard for asynchronous communication.
• JMX (Java Management Extensions): Remote monitoring and management of Java applications.

Annotations

• @Component, @RestController, @Repository, @Service: Annotations used for

component scanning and auto-detection of Spring-managed beans.

• @Autowired: Autowires dependencies by type or qualifier.
• @RequestMapping, @GetMapping, @PostMapping, @PutMapping, @DeleteMapping, @PatchMapping: Annotations for mapping HTTP requests to controller methods.
• @PathVariable: Binds a path variable from the URL to a method parameter.
• @RequestBody: Binds the HTTP request body to a method parameter.
• @RequestParam: Binds a request parameter to a method parameter.
• @ModelAttribute: Binds request parameters to a model object.
• @SessionAttribute: Binds session attributes to a method parameter.
• @InitBinder: Customize data binding process or register custom binders.
• @ExceptionHandler: Handles exceptions thrown within a controller and returns appropriate responses.

Development with POJO Objects

• POJO Objects: Plain Old Java Objects used to represent structured data.
• Development with POJO objects is a common approach in Java Spring development. It allows for the creation of simple and reusable objects without any specific framework dependencies.

WAR File - Web Application Archive

• WAR (Web Application Archive) is a file format used for packaging web applications.
• A WAR file contains the necessary files and directories to deploy a web application on a web server.
• In Java Spring development, WAR files are often used to package and deploy Spring applications on a web server.

Dependency Injection

• Dependency Injection is a design pattern used in Spring to achieve loose coupling between components.
• It allows for the injection of dependencies into an object, instead of the object creating or managing its dependencies.
• Spring provides various mechanisms for dependency injection, such as constructor injection and setter injection.

Minimizing Boilerplate Code

• Minimizing boilerplate code is a common goal in Java Spring development.
• Spring provides helper classes, annotations, and frameworks to reduce repetitive code and increase productivity.
• By leveraging these tools, developers can focus more on business logic and application-specific code.

CORE Container

• The CORE Container in Spring is responsible for managing object creation and dependency injection.
• It has a bean factory that creates and manages beans, which are the objects managed by the Spring container.

AOP - Aspect-Oriented Programming

• AOP (Aspect-Oriented Programming) is a programming paradigm that allows for modularizing cross-cutting concerns in an application.
• Spring provides support for AOP, allowing developers to separate concerns such as logging, security, and transactions from the main application logic.
• By using AOP, these concerns can be applied uniformly across multiple components without the need for individual import statements.

Data Access Layer

• The Data Access Layer in Spring focuses on accessing databases and handling data persistence.
• Spring provides support for different data access strategies, such as JDBC (Java Database Connectivity) and ORM (Object-Relational Mapping) frameworks like Hibernate.
• These tools help reduce the amount of source code required for database access and provide convenient abstractions for working with data.

JMS - Java Message Service

• JMS (Java Message Service) is a messaging standard for asynchronous communication between applications.
• Spring offers support for JMS, allowing developers to integrate message queues and implement asynchronous processing in their applications.
• JMS can be used to decouple components, enable event-driven architectures, and improve scalability.

Transactions

• Transactions are used to ensure the consistency and integrity of data when multiple operations need to be performed as a single unit.
• Spring provides transaction management support, allowing developers to define and control transactions declaratively using annotations such as @Transactional.
• Transactions help maintain data integrity and support ACID (Atomicity, Consistency, Isolation, Durability) properties.

Web Layer

• The

Web Layer in Spring is responsible for handling web requests and generating appropriate responses.

• It includes components such as controllers, views, and templates that facilitate the development of web applications.
• Controllers handle incoming HTTP requests, map them to specific methods or classes, and generate responses.
• The MVC (Model-View-Controller) pattern is commonly used in the web layer to separate concerns and maintain a clear structure.
• Web remoting involves exposing services over the web using technologies like RESTful APIs or SOAP.

JMX - Java Management Extensions

• JMX (Java Management Extensions) is a technology used for monitoring and managing Java applications.
• Spring provides support for JMX, allowing developers to expose management interfaces and perform remote monitoring and management of their applications.
• With JMX, developers can monitor application metrics, configure runtime behavior, and perform diagnostic tasks.

Test Layer

• The Test Layer in Spring involves writing unit tests and integration tests to ensure the correctness and functionality of the application.
• Unit tests focus on testing individual components or classes in isolation, typically using frameworks like JUnit.
• Integration tests involve testing the interaction between multiple components or modules to validate the integration and behavior of the system as a whole.

Spring Bean Lifecycle

• Spring beans go through a lifecycle, including initialization and destruction phases, managed by the Spring container.
• Initialization Phase:
  • Instantiation: The bean is created by invoking its constructor.
  • Property Population: Dependencies and properties of the bean are injected.
  • BeanNameAware and BeanFactoryAware: Callbacks for beans aware of their bean name or the bean factory.
  • BeanPostProcessor: Customization hooks for modifying the bean instance.
  • InitializingBean and @PostConstruct: Callbacks for custom initialization logic.
• Usage Phase:
  • Bean is ready for use.
• Destruction Phase:
  • DisposableBean and @PreDestroy: Callbacks for custom destruction logic.
  • Destruction of the bean instance.