Difference between @AutoWired and @Qualifier in Spring Framework?

Hello guys, if you are preparing for Spring Framework or Spring Boot interviews then you should always prepare comparison questions like what is difference between @Qualifier and @AutoWired annotation in Spring? This kind of questions are good to demonstrate not only your knowledge but also how well you understand them and its also your chance to impress the interviewer. In the past, I have answered @Bean vs @Component and @Controller vs @RestController annotation and in this article, I am going to explain you the difference between @Autowired and @Qualifier in Spring Framework. 

How to Solve "Error starting Application Context" in Spring Framework?

 Hello guys, Spring Boot is a popular framework for building Java applications, providing a streamlined development experience. However, like any software, Spring Boot applications can encounter errors during startup. One common error that developers may encounter is the "Error starting ApplicationContext" error. This error typically indicates an issue with the application's configuration or dependencies but it's really hard to find what exactly is wrong and how to fix it. In the past, I have shared tips on how to fix error creating bean error and In this article, we will explore various solutions to fix this error and ensure a successful startup of your Spring Boot application.

Top18 Spring Cloud Features for Microservices Architecture in Java

Hello guys, If you are doing Java development using Spring Boot then you may already know that Spring Cloud is a popular open-source framework for implementing microservices in Java. It provides a wide range of features that simplify the development, deployment, and management of Microservices in Java. In this article, we will discuss some of the key features of the Spring Cloud framework that makes it an excellent framework for developing Microservices in Java. Microservices architecture is a modern approach to building complex applications as a collection of loosely coupled, independently deployable services. 

What is Backend for front-end pattern in Microservices? How to use it? Example Tutorial

Hello guys, as Organizations embrace Microservices architecture, the need for efficient communication and collaboration between front-end and back-end teams becomes crucial. To address this, the Backend for Front-End (BFF) pattern has emerged as a valuable approach. BFF pattern allows front-end developers to have dedicated back-end services that cater specifically to their needs, enabling them to build user interfaces more effectively.  In the past, I have shared several Microservices design patterns like  Event Sourcing, SAGA, Database Per Microservices, CQRS, API Gateway, Aggregator Design Pattern,  and also shared best practices to design Microservices and in this article, I am going to talk about the Backend for Front-End pattern entails and how to effectively utilize it in microservices architecture.

What is Circuit Breaker Design Pattern in Microservices? How to implement it?

Hello guys, Microservices design patterns are very important concepts for Java developers to learn, not just to create a robust, scalable, and high-performance Microservice architecture but also to do well on Java developer interviews. In the past, I have shared several Microservices design patterns like e Event Sourcing, SAGA, Database Per Microservices, CQRS, API Gateway, and also shared best practices to design Microservices and in this article, I am going to talk about Circuit-Breaker Design Pattern, and how you can implement in Java using Spring Cloud Framework.  This is not just an important Microservice Pattern but also a popular Microservice question which I have also mentioned earlier in my article about 15 Microservices questions for Interviews. If you haven't read that article yet, I suggest read it, especially if you are preparing for Java and Microservice interviews. 

What is @Conditional annotation in Spring Framework? Example Tutorial

Hello guys, if you want to know what is @Conditional annotation in Spring Framework and Spring Boot, and how to use it then you have come to the right place. Earlier, I have shared best free courses to learn Spring Framework and Spring Boot, and in this article, you'll learn what they are, how to use them with practical examples. Spring 4.0 introduced the @Conditional annotation that is used for conditional checking for bean registration. This annotation offers more support than the @Profile annotation provided by the spring framework and most of the Spring Boot matching is attributed to this annotation. It allows you to setup features based upon certain conditions like presence of a class in classparth or a JAR File which is how Spring Boot Auto-configuration works.

Difference between @Controller vs @RestController in Spring Framework

Hello and welcome to the blog post. If you are preparing for Java or Spring Boot interview, you may have come across this topic. In this article, we are going to have a look at the difference between @Controller and @RestController annotation. Let's understand with the help of an example.
Spring Framework is a popular open-source application framework that provides infrastructure support for developing Java applications. One of the essential components of Spring Framework is the controller, which is used to handle HTTP requests and provide responses to clients. In Spring, there are two types of controllers: @Controller and @RestController.

Difference between @RequestParam and @PathVariable in Spring MVC

Hello guys, if you are wondering what is difference between @ReqestParam and @PathVaraible annotation in Spring MVC, most likely because it was asked to you on a Java and Spring interview or maybe you are just curious then you have come to the right place. In the past, I have talked about difference between @Component, @Service, @Reposistory and @Controller annotations and in this comprehensive article we are going to take an in-depth look at the difference between the two most frequently used annotations in Spring MVC. It provides two commonly used annotations, namely @RequestParam and @PathVariable, which play a significant role in parameter handling within web applications. 

Differences between OAuth 2.0 and JWT (JSON Web Token)

Hello guys, both OAuth 2.0 and JWT (JSON Web Tokens) are two widely used authentication and authorization protocols in modern web applications. While both serve similar purposes, there are some key differences between the two that are important to understand, which we will see in this article. This is also an important interview question and if you are preparing for Java and Microservices developer interviews, it's better to know how this two technology works and what are the key differences between then.  In short, OAuth 2.0 is primarily used for authorization, whereas JWT is primarily used for authentication. OAuth 2.0 uses access tokens, whereas JWT is a self-contained token. OAuth 2.0 has a complex authorization flow, whereas JWT has a simple flow. OAuth 2.0 provides better security as it reduces the risk of unauthorized access to protected resources, while JWT can be intercepted if not properly secured. OAuth 2.0 access tokens are short-lived and need to be refreshed periodically, whereas JWTs do not expire.

3 Ways to return different content types from Spring MVC Controller? @RequestMapping and ResponseEntity Example Tutorial

Hello guys, if you want to provide different types from a Controller in Spring MVC and wondering how to do that then you have come to the right place. In the past, I have shared the free Spring MVC courses, books, and interview questions and in this article, I am going to show you three ways to send different content types from Spring Controller. There are various content types for a controller and we are going to discuss them in this tutorial. So we are going to discuss how to interpret the data present in the request and response. JSON is one of the media formats that may be consumed/produced using this request-response architecture.

Difference between @RequestParam vs @RequestBody in Spring MVC? (with Example)

Hello everyone, in this article, we are going to look at an interesting topic from the Java Spring framework and the topic is, to find the difference between @RequestBody and @RequestParam. If you don't know this is one of the frequently asked Spring MVC interview question and also two of the most used annotation when creating backend of a Java web application in Spring Framework. Earlier, I have explained difference between @RequestBody and @ResponseBody in Spring MVC and REST APIs, and in this article, I am going to tell you the difference between @RequestBody and @RequestParam annotation in Spring Framework. It is worth noting that these two annotations are frequently used in Spring Boot REST API.

10 Examples of RestTemplate in Spring Framework

Hello guys, if you are wondering how to send GET and POST request to your API or Web Service from a Java based Spring Framework then you would be glad to know that You can use use RestTemplate class from Spring Framework. It's a fully functional HTTP client which is really really useful in this age of API. I have used RestTemplate to consume JSON from API before as well as sending different kind of request like POST, PUT, DELETE and PATCH to any REST API. For example, in this article, I shared how to send POST request using RestTemplate and how to set header on HTTP request using RestTemplate. Yes, RestTemplate also allow you to send headers like Authorization on Http Request. 

What is @Component annotation in Spring? What does it do?

Hello guys, One of the main reason many people use Spring Framework is Dependency injection and auto-wiring, which means you don't need to write code to create and inject dependency, Spring will do it for you. But does it do it and how @Component annotation helps? Well, In Spring, the @Component annotation is used to mark a class as a Spring bean that should be managed by Spring's Inversion of Control (IoC) container. When a class is annotated with @Component, Spring automatically scans for such components during application startup and creates instances of these components that can be used for dependency injection. The @Component annotation is the foundation for other stereotype annotations in Spring, such as @Service, @Repository, and @Controller, which are specializations of @Component. These annotations are used to further specify the role and purpose of a component in a Spring application.

How to fix "not a managed type exception" in JPA? [Solution]

Hello folks, JPA (Java Persistence API) is a widely used technology in Java applications for object-relational mapping (ORM) and working with databases. However, when using JPA, you may encounter the "not a managed type" exception, which is a common error that occurs when JPA fails to recognize an entity class as a managed type. This exception can occur due to various reasons, such as incorrect package or class names, missing annotations, or misconfiguration of JPA settings. Fixing this error requires identifying the root cause and taking appropriate steps to resolve it. In this article, we will explore different strategies and solutions to fix the "not a managed type" exception in JPA, helping you overcome this hurdle and successfully work with JPA in your Java applications.

Top 10 Spring Framework Annotations Java Developer Should Learn - Example Tutorial

Hello guys, if you are learning the Spring framework and want to know what are essential Spring annotations you should know then you have come to the right place. Earlier, I have shared the free Core Spring and Spring Boot courses and Spring certification resources for Java developers, and in this article, you will find some of the most common annotations in this article, which is a must for a Java developer to work with Spring. You will also learn what does annotation really does and why should you learn them. There is no doubt that the Spring framework is one of the most popular Java frameworks, and it has made the life of Java developers easy by providing some excellent features in the last 15 years. 

Top 5 Spring Cloud Annotations for Java Microservices

Hello guys, If you are developing a Java application for Cloud, then you should learn Spring Cloud, a great framework and extension of the popular Spring framework, which can help you to develop a cloud-native Java application. Spring Cloud provides several necessary services required for a cloud-based Java application and Microservices like configuration management, service discovery, circuit breakers, intelligent routing, micro-proxy, a control bus, one-time tokens, global locks, leadership election, distributed sessions, cluster state, etc.

What is ContextLoaderListener in Spring MVC? Example Tutorial

The ContextLoaderListner is one of the essential components of the Spring MVC framework, probably the most important after the DispatcherServlet itself. It is used to create the root context and responsible for loading beans, which are shared by multiple DispatcherServlet like beans related to the service layer and data access layer. In general, When you develop Spring MVC based web applications and also using Spring in the services layer, you need to provide two application-contexts. The first one is configured using ContextLoaderListener, and the other is set using DispatcherServlet. The DispatcherServlet is responsible for loading web component-specific beans like controllers, view resolvers, and handler mappings while, as I said before, ContextLoaderListener is accountable for loading middle-tier and data-tier beans which forms the back end of Spring applications.

How to enable HTTP Caching in Java Web application with Spring MVC? Cache-Control Header Example

One of the standard requirement in a secure Java web application is to disallow the back button of the browser or invalid the session if the user hit the back button of the browser. You might have seen this behavior while doing online banking or net banking, almost all the banks don't allow you to use the browser's back button. Your session gets terminated as soon as you hit the back button, and you have to log in again to do any transaction. Btw, have you ever checked some situations on your Servlet and JSP-based Java web application, like, if you pressed the back button of your browser after logging in, what happened? You will find that the browser takes you to the previous page.

What is @PropertySource Annotation in Java and Spring? PropertySource Example Spring Boot

Hello Java developers, if you are using Spring Framework or Spring Boot in your new project and wondering what is property source in Spring Framework and how to use @PropertySource annotation then you have come to the right place. Earlier, I have shared the best books and online courses to learn Spring Framework and in this article, I will teach you how to use @PropertySource annotation in Spring to read Environment variables and inject properties using @Value annotation. In the Spring application, one of the files that are needed to provide properties to the Spring environment is the @Configuration classes. 

How @Configuration, @Component, and @ComponentScan annotations works in Spring Framework? Component Scanning Example

Hello guys, if you are wondering how to does autowiring work in Spring Framework and how does Spring Framework find dependency in runtime then you have come to the right place. Earlier, I have explained How Spring MVC works and how Spring Security works, and In this tutorial, I will tell you how component scanning and auto-wiring works in Spring. You will also learn how to enable component scanning in a Spring application. When you develop a software application using spring, you need to tell the Spring framework where to look for Spring components. Using component scanning it is very much easier as this enables auto-detection of beans by spring container and smoothly.