Category: Spring

Last update:Posted on

What is Spring bean?

In short, a Spring bean is an object which Spring framework manages at runtime. A Spring bean is a basic building block of any Spring application. Most of the application logic code you write will be placed in Spring beans.

The management of a Spring bean includes:

  • creating an object
  • providing dependencies (e.g. other beans, configuration properties)
  • intercepting object method calls to provide additional framework features
  • destroying an object

A Spring bean is a fundamental concept of the framework. As a user of Spring, you should have a deep understanding of this core abstraction.

Keep reading and you’ll find out all you need to know about Spring beans.
Continue reading “What is Spring bean?”

Last update:Posted on

Injecting Spring Prototype bean into Singleton bean

Have you ever wonder why singleton is the default scope for Spring beans? Why isn’t it prototype?

It’s not a random choice. It’s because the vast majority of business logic we create can be safely kept in stateless objects. And the best choice for stateless beans is the singleton scope. The prototype scope is better for stateful beans to avoid multithreading issues.

Yet, sometimes you need to mix both and use a prototype bean in a singleton bean. This particular case is a bit tricky. In this article, I’m going to explain to you different ways of accessing prototypes in singletons.

So let’s begin.

Continue reading “Injecting Spring Prototype bean into Singleton bean”

Last update:Posted on

How to bind @RequestParam to object in Spring

Do you have multiple parameters annotated with @RequestParam in a request mapping method and feel it isn’t readable?

The annotation looks pretty straightforward when there’s one or two input parameters expected in a request but when the list gets longer you might feel overwhelmed.

You cannot use the @RequestParam annotation inside objects but it doesn’t mean you’re left with no other solution. In this post, I’m going to show you how to bind multiple request parameters to an object in Spring application.

Continue reading “How to bind @RequestParam to object in Spring”

Last update:Posted on

Spring Boot application.properties file

Spring Boot comes with a built-in mechanism for application configuration using a file called application.properties. In this article, I’ll show you how to effectively use the application.properties file in custom scenarios.

I’m not going to discuss properties specified by the Spring Boot framework. Working with existing configuration keys is pretty straightforward. You can easily find common keys in the official documentation.

This post covers defining custom properties, handling data types, and working with properties on different runtime environments. If that’s what you’re looking for, keep on reading.

Continue reading “Spring Boot application.properties file”

Last update:Posted on

Spring Custom Validator by example

Since you’re here, you probably reach the point in which standard annotations like @NotNull or @Size don’t meet your expectations. Fortunately, I have good news for you. Creating a custom validation annotation is pretty easy. In this post, you will learn how to create a custom constraint annotation and a corresponding validator class. You will also see how to use Spring beans inside a custom validator.

Let’s just right into it.

Continue reading “Spring Custom Validator by example”

Last update:Posted on

Spring bean thread safety guide

Is Spring controller/service/singleton thread-safe?

It’s a commonly asked question by Spring newcomers and probably a must-have warm-up question on job interviews. As usual in programming, the answer is: it depends. The main factor which determines thread safety of a component is its scope.

Let’s get down to it and see what Spring’s scopes have to offer in multithreaded programming.

Continue reading “Spring bean thread safety guide”

Last update:Posted on

HTTP cache with Spring examples

Caching is a powerful feature of the HTTP protocol but for some reason, it’s mainly considered for static resources like images, CSS stylesheets, or JavaScript files. However, HTTP caching isn’t limited to application’s assets as you can also use it for dynamically computed resources.

With a small amount of work, you can speed up your application and improve the overall user experience. In this article, you will learn how to use the built-in HTTP response cache mechanism for Spring controller’s results.

Continue reading “HTTP cache with Spring examples”

Last update:Posted on

Feature toggle in Spring Boot 2

Whether you like it or not, software development is a collaborative activity. Integration work has always been demonized and treated as necessary evil. There are several approaches which try to solve the challenge of effective integration. The feature toggle belongs to that group. In this article, you’ll see in practice how feature toggles, also known as feature flags, can be used in your Spring Boot application.

Continue reading “Feature toggle in Spring Boot 2”