Spring

Spring @RequestParam Annotation

Introduction: Spring @RequestParam annotation can be used to extract the query parameters in a handler method. In this quick tutorial, we’ll learn its usage. @RequestParam Annotation: Let’s first expose an API which returns a list of users with a given first nameĀ and age:

And now, let’s use cURL to quickly test this out:

[…]

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Spring

Spring @Primary Annotation

Introduction: Spring @Primary annotation is used to give a higher preference to the marked bean when multiple beans of the same type exist. Spring, by default, auto-wires by type. And so, when Spring attempts to autowire and there are multiple beans of the same type, we’ll get a NoUniqueBeanDefinitionException:

To solve this, we can […]

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Spring

Spring @Lazy Annotation

Introduction: The Spring framework, by default, loads and eagerly initializes all beans at the application startup itself. In our application, we might have some pretty resource-intensive beans. We’ll prefer to load such beans on a need basis. We can achieve this using the Spring @Lazy annotation. In this tutorial, we’ll learn how to use @Lazy […]

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Spring

Spring @Order Annotation

Introduction: The Spring @Order annotation was first introduced in Spring 2.0. It was then used only to define the order among the AspectJ advices. Later in Spring 4.0, the implementation of this annotation was further improved a bit. Since then, it also supports ordering of Spring components or beans in a collection like a Java […]

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Spring

Spring Boot: Building a RESTful Web Application

Introduction: REST stands for Representational State Transfer and is an architectural guideline for API design. We assume that you already have a background in building RESTful APIs. In this tutorial, we’ll design a simple Spring Boot RESTful web application, exposing a few REST endpoints. Project Setup: Let’s start by downloading the project template via Spring […]

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Spring

Spring Boot with H2 Database

Introduction: In this quick tutorial, we’ll bootstrap a simple Spring Boot application backed by an in-memory H2 database. We’ll use the Spring Data JPA to interact with our database. Project Setup: Firstly, let’s generate our project template using Spring Initializr: On clicking the ‘Generate the project’ link, our project files will get downloaded. Now, if […]

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Spring

@SpringBootConfiguration Annotation in Spring Boot

Introduction: @SpringBootConfiguration annotation in Spring Boot is a class-level annotation which indicates that this class provides the application configuration. Generally, the class with the main() method is best-suited for this annotation. We usually use @SpringBootApplication annotation which automatically inherits the @SpringBootConfiguration annotation. Annotation Usage: When we mark a class with @SpringBootConfiguration, it means that the […]

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Spring

Spring Boot CommandLineRunner and ApplicationRunner

Introduction: In this quick tutorial, we’ll explore the two very popular interfaces in Spring Boot: CommandLineRunner and ApplicationRunner. One common use case of these interfaces is to load some static data at application startup. Though, I have seen such usages mostly for test data setup only. Both of them are functional interfaces with a run() […]

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Spring

Introduction to Spring Boot

Introduction: In this tutorial, we’ll take a look at Spring Boot and see how it’s different from the Spring framework. We’ll also discuss various features offered by Spring Boot. What is the Spring Boot? Spring is a powerful framework when it comes to developing enterprise-level applications. It provides us with features like dependency injection along […]

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Other Tutorials

Identifying Code Smells In Java

Introduction: As a software developer, it’s our responsibility to not only write code that works but rather write code that’s maintainable. Martin Fowler in his book Refactoring: Improving the design of existing code defines a code smell as: A surface indication that usually corresponds to a deeper problem in the system Refactoring is a process […]

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