Spring > Introduction

What is Spring?

Spring is a powerful, lightweight framework for building Java-based enterprise applications. It provides comprehensive infrastructure support, helping developers create scalable, maintainable, and secure applications.

Why Learn Spring?

• Lightweight – Minimal overhead with a modular architecture.
• Flexible – Supports multiple configurations (XML, Java-based, and annotations).
• Enterprise-Ready – Used for web applications, microservices, and cloud-native apps.
• Dependency Injection (DI) – Manages object dependencies efficiently.
• Aspect-Oriented Programming (AOP) – Enables separation of cross-cutting concerns.

How Spring Works

Spring provides a container-based approach where dependencies are managed automatically.

1. Define Beans – Components are defined as Spring-managed beans.
2. Configure Dependencies – Using XML, annotations, or Java-based configuration.
3. Inject Dependencies – Spring injects required dependencies automatically.
4. Run Application – Spring Boot makes it easy to run applications with minimal setup.

Basic Structure of a Spring Boot Application

Spring Boot simplifies Spring development with a minimal setup. Here’s a simple example:

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

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

Explanation:

• @SpringBootApplication – Marks this class as a Spring Boot application.
• SpringApplication.run(...) – Boots up the Spring application.

Key Features of Spring

Spring offers several powerful features:

1. Inversion of Control (IoC) – Manages object creation and dependency injection.
2. Spring MVC – Framework for building web applications.
3. Spring Boot – Simplifies Spring application development.
4. Spring Data – Simplifies database access.
5. Spring Security – Provides authentication and authorization.
6. Spring Cloud – Helps in building cloud-native applications.

Spring Core Concepts

Spring is built on several core concepts:

1. Dependency Injection (DI) – Helps manage object dependencies efficiently.
2. Bean Lifecycle – Defines how beans are created, initialized, and destroyed.
3. ApplicationContext – Central container that manages beans.
4. Transaction Management – Handles database transactions seamlessly.

Example of Dependency Injection

import org.springframework.stereotype.Component;
import org.springframework.beans.factory.annotation.Autowired;

@Component
class Engine {
    public void start() {
        System.out.println("Engine started!");
    }
}

@Component
class Car {
    private final Engine engine;
    
    @Autowired
    public Car(Engine engine) {
        this.engine = engine;
    }
    
    public void drive() {
        engine.start();
        System.out.println("Car is moving...");
    }
}

Explanation:

• @Component – Marks the class as a Spring-managed bean.
• @Autowired – Injects dependencies automatically.

Spring simplifies Java development by providing a comprehensive and modular framework. Learning the fundamentals of Spring will help you build scalable, enterprise-level applications efficiently.

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🔗 Related Topics:

• Spring Architecture
• Spring Modules

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