Design Patterns in Spring Framework

Design Patterns in Spring Framework

spring-framework-design-patterns

Introduction

These solutions not only solve recurring problems but also help developers understand the design of a framework by recognizing common patterns.

The most common design patterns in Spring:

1. Dependency Injection
2. Singleton pattern
3. Factory Method Pattern
4. Proxy Pattern
5. Template Pattern

1. Dependency Injection

It is a pattern to implement Inversion of Control (IoC).

Makes a class independent of its dependencies. It achieves that by decoupling the usage of an object from its creation.

Inversion of Control is a principle in software engineering by which the control of objects or portions of a program is transferred to a container of framework.

2. Singleton Pattern

The singleton pattern is a mechanism that ensures only one instance of an object exist per application. This pattern can be useful when managing shared resources or providing cross-cutting services, such as loggin.

Singleton Beans.
Spring restricts a singleton to one object per Spring IoC container.

3. Factory Method Pattern

The factory method pattern entails a factory class with an abstract method for creating the desired object.

To accomplish this, we can create a factory implementation for each desired object and return the desired object from the concrete factory method.

Application Context

Spring uses this technique as the root of its Dependency Injection Framework. Spring treats a bean container as a factory that produces beans.

External Configuration

We can completely change the application’s behavior based on external configuration.
For example, we can change the AnnotationConfigApplicationContext to an XML-based configuration class.

4. Proxy Pattern

The proxy pattern is a technique that allows one object, the proxy, to control access to another object (the subject or service).

Transactions. Without a proxy, Spring wouldn’t be able to control access to our a Transactional bean and ensure its transactional consistency.

Template Method Pattern

The template method pattern is a technique that defines the steps required for some action, implementing the boilerplate steps, and leaving the customizable steps as abstract.

Templates and Callbacks. Subclasses can then implement this abstract class and provide a concrete implementation for the missing steps.