Capture long running method execution in Spring Boot using annotation
It is crucial to capture long running method execution in your application (whether it is an API or traditional mvc application). You should also …
Graceful Shutdown in Spring Boot and multithread environment
Spring provides reliable shutdown of the application using feature called Graceful Shutdown. With Graceful shutdown feature we can close the …
Use Junit 5 in Spring Boot version 2.1.x
Some of the older versions of Spring boot supports Junit 4 (with Junit 5 dependencies as well). If you want to use Junit 5 in in your spring boot …
@RequestHeader annotation in Spring Boot
@RequestHeader annotation is used to bind a request header to a method argument in a controller. In other words, it allows us to read http headers in …
Git cherry pick
git cherry-pick is useful command to pick specific commit or multiple commits from another branch and merge it to another branch(or we can say that …
Git Interview Questions
Git is a tool for keeping track of changes in computer programs. It’s free to use and lots of people in the software field use it. Now, …
Using Git Professionally
In this long blog, we are going to improve our git knowledge. I will try to explain the some concepts behing the basic things in git. Writing perfect …
How to disable async operation for specific test cases in Spring Boot
I was facing a challenge with running test cases that include async methods in my Spring Boot application. The test cases failed because the async …
How to change running port in spring boot?
There are 3 ways to change default running port in spring boot application: By default, the embedded server starts on port 8080. 1- Use Property files …
What spring boot version am I using?
It is so easy to learn your spring boot version. To learn that you have to look at the following files (according to project tool you are using): If …
Integrate Google reCAPTCHA v3 into Spring Boot and Vue 3 (Nuxt 3)
Integrating Google reCAPTCHA v3 with spring boot applications can greatly enhance security and protect against malicious activities, such as spam and …
How to resolve Content type 'application/x-www-form-urlencoded;charset=UTF-8' not supported in your Spring Boot project
Most probably you have encounter the following error, while waiting response from other services(for instance it could be payment response from the …
How to validate object programmatically in Spring Boot
Validating objects is crucial to ensure data integrity and prevent errors in subsequent layers of the application. While the @Valid annotation is …
Creating base class (abstract entity class) for all entities in your Spring Boot project
As developers, we often find ourselves faced with the challenge of managing multiple entities that share common attributes and behavior. By leveraging …
Pattern Matching and Template Verification in Java: Ensuring Text Consistency
Let’s assume that you have the following message template in which clients send the text with the correct parameter. Here is the template: …
Creating entity with includes nested data structures in Hibernate 6 (and in Spring Boot 3)
Sometimes your entity might need store nested data structures such as Map<String, Map<String, String> or list of list etc.. If you want to …
How to convert JSON into generic Java classes using Jackson (avoiding error LinkedHashMap cannot be cast to ...)
Jackson is a popular Java library for working with JSON. Even it is easy to use, when converting a JSON string to a generic Java class, such as …
Why I am moving my github page to mehmetozanguven.com
After careful consideration, I have decided to move my GitHub page(https://mehmetozanguven.github.io) to my own domain, mehmetozanguven.com. This has …
Modern Spring Boot v3 with Thymeleaf, TailwindCSS and AlpineJS
In this tutorial, we will integrate Spring MVC with gulp and webpack. As you know creating Spring MVC project with Thymelaef project is so easy. But …
gulpjs for backend developers
This mini tutorial is especially for backend developers who implement also frontend part of the application inside the one package. Today, gulp seems …
How to paginate and sort for join queries in Spring Boot
Let’s say you have two entities which has many-to-one relationship and you want to paginate your query on the parent side with additional colums …
JavaFX - What are the Scene and Stage ?
Scene This is the one of the fundamental classes in JavaFX A Scene represents the content area of window (not include the window’s border and …
JavaFX and CSS (Final)
We can use CSS(Cascading Style Sheets) to change visual appearance of our JavaFX program. Anything that can be done with CSS can also be done with …
JavaFX GridPane and TilePane
GridPane Layout children nodes in rows and columns Rows and columns are numbered, starting from zero. Each rows and columns have not the same width …
JavaFX BorderPane HBox and VBox
BorderPane BorderPane can be useful for displaying one large central component with four smaller components at left, top, right and bottoms Note you …
JavaFX Basic Layouts
In this blog post, let’s talk about laying out the components in the JavaFX. We need a pre-defined layout solution because computing the …
JavaFX Basic Inputs and Controls
If you are going to draw something on the screen and handle some mouse event, then you can only use MouseEvent listener and AnimationTimer …
JavaFX Basic Events
In JavaFX, events are represented by objects. When an event occurs, system collects all the information relevant to the event and construct an object …
JavaFX Canvas and GraphicsContext
The screen of a computer is a grid of little squares called pixels. The color of each pixel can be set individually, and drawing on the screen just …
JavaFX Color and Paint
Color Computer color uses an RGB color system which means that color on the a computer screen is specified by three numbers called color components, …
JavaFX Getting Started
GUI programs are different from the traditional program that you have encountered. GUI programs are event-driven which means that these programs …
How to add robots.txt and sitemap.xml into Quasar(VueJs) Framework
Adding robots.txt and/or sitemap.xml can be cumbersome for the modern javascript framework such as VueJs, React or Angular etc.. In this short blog, I …
Kadane's Algorithm - Optimal Solution to Maximum Subarray Problem
Kadane’s algorithm could be a good solution to find maximum subarray in the given list. First let’s describe the maximum subarray problem. …
Running MongoDB with Podman
Instead of running MongoDB locally, we can easily run with Podman. Here are the basic steps you should follow: Pull the latest images podman pull …
Create simple hash map with expiration(time-to-live) feature
You want to add & use simple cache in your application via hash map, but also you want your cache to remove automatically expired …
Threads in Java
Like people, computers can multitask. They can be working on several different tasks at the same time. A computer that has just a single central …
Optimal Stopping - Look-then-Leap Rule and Practical Implementation with Java
In this article, we are going to dive into the what is the optimal stopping and we are going to write practical implementation with Java. First, …
Utility script for pretty printing kafka consumer log
Recently, I had to listen kafka consumer log to identity bug I have found in my web application. But listening kafka consumer logs via console output …
How to use cache in Spring Boot applications without annotation(s)
Almost every blog(s) on the Internet for caching operation in the Spring Boot are using @Cacheable, @CacheEvit, @CachePut vs… In this blog we …
Running Spring Boot Application with Podman
To run spring boot application in a container. We should do the following steps: Create a jar package with maven or gradle (mvn clean install or mvn …
Running PostgreSQL with Podman
Instead of running postgresql locally, we can easily run with Podman. Here are the basic steps you should follow. Search available Postgres Images You …
Podman Tutorial
In this one-shot tutorial, we are going to learn what Podman is, how to use it, the differences between Docker and Podman and more.. What is Podman? …
How to read properties file only once in the Spring Boot application
Do you want to know how to read specific properties file according to the environment variable in Spring boot? Let’s explore how to read …
Java 8 Date and Time API in one tutorial
Even we have Java 17 version right now, industries still are using Java 8 & 11 even old ones using Java 6. Also many of these industries are using …
How to create sitemap.xml controller in Spring Boot
Let’s quickly learn how to generate sitemap.xml endpoint for your spring boot project. We will create a sitemap controller to handle sitemap.xml …
How to create robots.txt controller in Spring Boot
Let’s learn how to create robots.txt file for your spring boot or spring mvc project. Having robots.txt file tells search engine crawlers, such …
How to catch all exceptions in Spring Boot
In this quick tutorial, let’s learn how to catch all exception(s) in Spring Boot. And most probably you want to return customized exception when …
Dockerfile Format and Commands
Before diving into the podman or docker itself, we should first know how to create dockerfile. Because writing a Dockerfile is the first step to …
Quick Intro to Container(s)
Recently, I decided to learn containers (specifically Podman) to simply run my applications in an isolated environment. I can directly jump into the …
Spring Boot OAuth2, Postgresql, Thymeleaf with Form based Authentication
Let’s implement oauth2 practical implementation with Spring Boot using PostgreSQL and Thymeleaf. In this application: We will use PostgreSQL to …
Spring Boot OAuht2 Reason for /oauth2/authorization/{id}
Do you know the reason why redirect URL should be http://localhost:8080/login/oauth2/code/google when we setup Authorization Server in the …
Spring Boot OAuth 2 Implementation with Thymeleaf
In this article, we will implement a basic single sign on application using Spring boot. We will use Thymeleaf for html pages A single sign-on (SSO) …
Spring Boot with OAuth2 - Theory
In this post, we are going to learn what the oAuth2 is, how to use OAuth2 in Spring boot. We will start with why do we need a OAuth2, we will look at …
Leaflet - JavaScript Library for Interactive Maps
Recently, I needed to create map on my project and to do that I had to learn Leaflet. After adding to the leaflet to my project, I think it is good to …
JPA Fundamentals & Hibernate - 13) Entity Lifecycle Events (Final)
In this article, we are going to learn lifecycle events in the JPA. As of the most application we will have date_created and last_modified column to …
JPA Fundamentals & Hibernate - 12) JPQL and Queries
In this article, we will learn what is the JPQL(The Java Persistence Query Language) and how to use it. What is the JPQL The Java Persistence query …
JPA Fundamentals & Hibernate - 11) Entity Manager
In this article, we are going to discuss what is the entity manager in the JPA and also learn the basic operations in the entity manager How to Obtain …
JPA Fundamentals & Hibernate - 10) Inheritance Strategies
In this article, we are going to look how to represent the inheritance relationship in the JPA and how to use @MapperSuperclass annotation Github Link …
JPA Fundamentals & Hibernate - 9) AssociationOverride
In this article, we are going to learn how to create relationship using @Embeddable & @Embedded object . @AssociativeOverride is used to override …
JPA Fundamentals & Hibernate - 8) Many To Many Relationship
In this post, we are going to learn how to create many-to-many relationship in JPA. Github Link If you only need to see the code, here is the github …
JPA Fundamentals & Hibernate - 7) One To Many & Many To One Relationship
In the OneToMany setup, Many sides must have the foreign key and it is the owner of the relatonship Github Link If you only need to see the code, …
JPA Fundamentals & Hibernate - 6) One To One Relationship & Cascade Operation
In this article, we are going to learn how to construct a one-to-one relationship between entities in the JPA and when to use Cascade operation Github …
JPA Fundamentals & Hibernate - 5) Composed Keys
In this article, we are going to find out how to create composite keys in JPA. Composite key is the key which composed of multiple columns. Github …
JPA Fundamentals & Hibernate - 4) @Embeddable and @Embedded
In this post, we are going to learn when and how to use embaddable object in Java and JPA. Github Link If you only need to see the code, here is the …
JPA Fundamentals & Hibernate - 3) @Enumareted, @Temporal and Date Types
In this post, we are going to learn @Enumarated and @Temporal annotations, how to store enums as ordinal and string and when to store enum types to …
JPA Fundamentals & Hibernate - 2) @Id generation
In this post, we are going to find out “what are the options to provide automatic Id generation instead of setting manually”. We will look …
JPA Fundamentals & Hibernate - 1) Entities and Context
In this series, we are going to learn the JPA fundamentals and we are going to use one of its implementation Hibernate. Before diving into the series, …
Check Sessions and Disk Storage in the PostgreSQL
Check Session If you want to list the current session for your database(s), you can use the following sql query: SELECT * FROM pg_stat_activity WHERE …
BackUp PostgreSQL with pg_dump
In this post, we are going to find out how to backup postgresql database with pg_dump utility. What is the pg_dump utility PostgreSQL provides the …
Spring Boot JWT Setup with Frontend (VueJs)
In this post, we are going to setup spring boot rest project with using JWT. we will also integrate the our spring boot application with the frontend …
How to resolve -- /var/lib/nginx/tmp/ Permission Denied Error
Recently I have encountered this error. Problem is that: user that runs nginx service has no permission to access /var/lib/nginx/tmp file. Example: …
Find Client's Location In Spring Boot with IP2Location and Update via Scheduling
In this tutorial, we are going to find location of your clients using spring boot and IP2Location and also we will look at how to update IP2Location …
How to resolve -- PR_CONNECT_RESET_ERROR
This error might releted to your Nginx configuration(at least problem was the nginx for me) After enable the SSL connection and try to connect from …
Spring Security -- 9) Spring Security CORS Setup
In this post, let’s find out what is the CORS policy, how to implement in the Spring Boot and Spring Security, finally how to resolve most …
Spring Security -- 8) Spring Security CSRF Attack Simulation & CSRF Setup and Customization (Cross-Site Request Forgery)
In this post, we are going to learn what CSRF(or XSRF) attack is, how to simulate csrf attack in spring and how to setup csrf protection in spring …
How to resolve -- Invalid Cors Request In Spring Boot
Recently I have encountered this error. And I can not send any request even I have setup corsConfiguration.setAllowedOrigins("*") . Response …
Spring Security -- 7) Security Context and Security Context Holder
In this post, let’s find out what the Security Context is I am going to use the project that I have implemented in the previous post. Here is …
Spring Security -- 6) Multiple Authentication Filters && Providers
In this post, let’s implement two steps authentication mechanism. This will be similar to JWT authentication but instead of JWT I will use my …
Spring Security -- 5) Filter Chain, Custom filter and Authentication
Let’s look at the Filter Chain, more specifically AuthenticationFilter in the Spring Security. And also I am going to implement custom filter. …
Spring Security -- 4) Implementing Custom Authentication Provider
In this post, I am going to answer to this question “what is the Authentication Provider” and I am going to implement a project includes …
Spring Security -- 3) UserDetailsManager, JdbcUserDetailsManager and BCryptPasswordEncoder
In this post, let’s look at the what UserDetailsManager is, differences between UserDetailsService. And also I am going to implement a project …
Spring Security -- 2) UserDetailsService
In this post, I am going to use real database to check the user against the request(s). Github Link If you only need to see the code, here is the …
Spring Security -- 1) Basic Concepts
In these short series , I am going to dive into what Spring Security is, how Spring Security works. Most of the example application would be for web …
Aspect Oriented Programming(AOP) with Spring Boot Example - 2
This is the second post for a short series of aspect oriented programming with the spring boot. In this post, I am going to implement a simple project …
Aspect Oriented Programming(AOP) with Spring Boot - 1
In this post, we are going to look at what is AOP and how your spring application matches with AOP concepts using Spring AOP module. After that we are …
Modern Web Mimarisi
Modern Web Mimarisi Yazılım geliştiriciler olarak günümüzün çoğunu kod yazarak geliştiriyoruz. Kimimiz kendi projesini geliştirirken, kimimiz …
Regex in one blog
In this post, we are going to learn Regex expression in one blog Let’s start with defining what is Regex or Regex expression. What is Regex? …
Apache Flink Series 10 - Reading Log files for State Example
In this post, I am going to read the log files from the application that I created in previous post. Here is the github link and also previous post …
Apache Flink Series 9 - How Flink & Standalone Cluster Setup Work?
In this post, I am going to explain, how Flink starts itself, and what happens when you submit your job to the Standalone Cluster setup Standalone …
Apache Flink Series 8 - State Backend & State Example
In this post, I am going to explain “what is state backend”, “which options do we have for state backend” , “how to configure state backend for your …
Apache Flink Series 7 — Create Sample Apache Flink Cluster on Local Machine — Part 2
In this post, I will create simple stream job and submit the job to the flink cluster. You can find the project in my github repo. This is the second …
Apache Flink Series 6 — Reading the Log files
In this post, we will look at the log files (both for TaskManager and JobManager) and try to understand what is going on Flink cluster. Actually this …
Apache Flink Series 5 — Create Sample Apache Flink Cluster on Local Machine — Part 1
In this post, we are creating simple Flink cluster own local machine. Before diving into creating cluster, configuration and etc.. let’s summarize …
Apache Flink Series 4 — DataStream API
In this post, I am going to explain DataStream API in Flink. You may see the all my notes about Apache Flink with this link When we look at the Flink …
Apache Flink Series 3 — Architecture of Flink
In this post, I am going to explain “Components of Flink”, “Task Execution”, “Task Chaining”, “Data Transfer”, “Credit-Based Flow Control”, “State …
Apache Flink Series 2 — Stream Processing Fundamentals
In this post, I am going to explain some terms about stream processing and also terms used in Apache Flink You may see the all my notes about Apache …
Apache Flink Series 1 — What is Apache Flink
In this post, I will try to explain what is Apache Flink, what is used for, and features of Apache Flink. You may see the all my notes about Apache …