Basics In Java

In this blog post, we will explore how to integrate Azure AD with a React.js application using the @azure/msal-browser and @azure/msal-react libraries. Prerequisites Node.js and npm installed on your machine React.js project set up ( create-react-app or similar) Azure AD tenant and registered application Step 1: Install Dependencies Start by navigating to your React.js project directory and install the required dependencies: $ npm install @azure/msal-browser@2.15.0 @azure/msal-react@1.0.1 Step 2: Configure Azure AD Next, you need to configure your Azure AD tenant and registered application. Follow these steps: Sign in to the Azure portal and navigate to the Azure Active Directory section. Under the "App registrations" tab, select your registered application or create a new one. Make note of the "Application (client) ID" as you'll need it later. Under the "Authentication" section

In a Spring Boot application, it's crucial to handle exceptions gracefully and provide user-friendly error messages when something goes wrong. One way to achieve this is by using a controller advice, which allows you to intercept and handle exceptions globally for all controllers. In this blog post, we'll explore how to write a controller advice in Spring Boot that catches all exceptions and returns user-friendly messages. Setting up the Controller Advice First, let's create a new class annotated with @ControllerAdvice and implement the ResponseEntityExceptionHandler class. This class will handle exceptions globally for all controllers in our Spring Boot application. import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.ControllerAdvice; import org.springframework.web.bind.annotation.ExceptionHandler; import org.springframework.web.servlet.mvc.method.annotation.ResponseE

Introduction Welcome to my blog post about CI/CD for Spring Boot projects. In this article, we'll explore the importance of Continuous Integration and Continuous Deployment in the context of Spring Boot applications. We'll discuss how CI/CD can streamline your development workflow, improve code quality, and help you deliver high-quality applications more efficiently. What is CI/CD? CI/CD stands for Continuous Integration and Continuous Deployment (or Continuous Delivery). It is a set of practices and processes that enable developers to build, test, and deploy code changes more frequently and reliably. CI focuses on integrating code changes from multiple developers into a shared repository, while CD focuses on automating the release and deployment of the integrated code. In traditional software development approaches, developers would work on separate branches for an extended period, leading t

Comparing FreeMarker, Thymeleaf, and Velocity Introduction to Templating Engines Templating engines are powerful tools that allow developers to separate the presentation logic from the business logic in web applications. They provide a way to define dynamic templates that can be rendered with data to produce HTML output. Framework Language Popularity Features FreeMarker Java Popular Robust, flexible, and widely used in Java projects. Thymeleaf Java Very popular Seamless integration with Spring, excellent support for HTML5, and natural templates. Velocity Java Less popular Lightweight, simple, and easy to learn. Code Examples FreeMarker Table Example: <table> <tr> <th>Name</th> <th>Age</th>

When working with Java Persistence API (JPA), it's essential to understand the different fetch types for entity associations. In JPA, you can define the fetch type for relationships between entities, which determines how related entities are loaded from the database. In JPA, the default fetch types for different mappings are as follows: One-to-One Relationship For a one-to-one relationship, the default fetch type is FetchType.EAGER . This means that the associated entity will be loaded from the database eagerly, along with the main entity. @Entity public class Author { // ... @OneToOne(fetch = FetchType.EAGER) private Address address; // ... } @Entity public class Address { // ... } One-to-Many Relationship For a one-to-many relationship, the default fetch type is FetchType.LAZY . This means that the associated entities will not be loaded from the database until explicit

Spring Boot provides a convenient way to configure application properties using YAML files. In a typical scenario, you might have different configurations for different environments such as development, testing, and production. Instead of maintaining multiple YAML files for each profile, you can configure multiple profiles within a single YAML file. This approach simplifies the configuration management process. Let's see how to achieve this. Step 1: Create a YAML Configuration File First, create a YAML file (e.g., application.yml ) in your Spring Boot project's resource directory. This file will contain the configuration properties for all the profiles you want to define. spring: profiles: active: dev logging: level: root: INFO com.example: DEBUG # Configuration for the 'dev' profile --- spring: profiles: dev database: url: jdbc:mysql://localhost:3306/devdb username: devuser password: devpassword # Co

When working with a Spring Boot application, you might need to override the spring.datasource.url property in the application.properties file to connect to a different database. Ways to Override the Property There are several ways to override the spring.datasource.url property: Using Command Line Arguments: You can pass the property value as a command line argument when running the application. For example: java -jar my-application.jar --spring.datasource.url=jdbc:mysql://localhost:3306/mydatabase Using System Environment Variables: Set the property value as an environment variable. For example, in a Unix-based system: export SPRING_DATASOURCE_URL=jdbc:mysql://localhost:3306/mydatabase Using an External Configuration File: You can provide an external properties file containing the override value. For example, create a file named application.yaml with the following content: spring: datasource: url: jdbc:mysql://local

In this blog post, we will discuss how to undeploy all processes when starting up a Spring Boot Camunda application. We will utilize the following code snippet: @PostConstruct public void undeployAll() { RepositoryService repositoryService = processEngine.getRepositoryService(); List<Deployment> deployments = repositoryService.createDeploymentQuery().list(); for (Deployment deployment : deployments) { repositoryService.deleteDeployment(deployment.getId(), true); } } Introduction When working with a Spring Boot Camunda application, there might be instances where you need to undeploy all existing processes during application startup. This could be necessary when you want to ensure a clean slate or update the deployed processes. In this blog post, we will explore a simple approach to achieve this using the provided code snippet. Step-by-Step Guide Step 1: Include Camunda Dependencies Make sure your Spring Boot project includes the necessar

In this blog post, we will learn how to configure a Progressive Web App (PWA) in Create React App and display the install icon on the Chrome browser. Step 1: Setting up a Create React App project First, make sure you have create-react-app installed globally. If not, install it by running the following command: npx create-react-app my-pwa Step 2: Configuring the manifest file Navigate to your project directory and open the public/manifest.json file. Modify the file with the following content: { "name": "My PWA", "short_name": "My PWA", "start_url": ".", "display": "standalone", "theme_color": "#000000", "background_color": "#ffffff", "icons": [ { "src": "path/to/icon.png", "sizes": "192x192", "type": "image/png" } ] } Step 3:

In this tutorial, we'll learn how to create an SSL certificate using mkcert , a simple tool developed by Filippo Valsorda. Mkcert allows us to quickly generate trusted development certificates for local testing purposes. Prerequisites Go to the mkcert repository on GitHub and follow the installation instructions for your operating system. Make sure you have Go installed on your machine. Step 1: Install mkcert To install mkcert, follow the instructions provided in the repository's README . Once installed, you should have the mkcert command available in your terminal. Next, run the following command to install the root CA (Certificate Authority) certificate into the system's trust store: mkcert -install This step is required to ensure that the certificates generated by mkcert are recognized as trusted by your operating system and web browsers. Step 2: Generate a Local SSL Certificate O

This blog post will guide you on serving a React static build folder with SSL using the serve CLI. Installation If you haven't installed the serve CLI yet, you can do so by running the following command: npm install -g serve Serving the Build Folder without SSL Make sure you have generated a static build folder for your React app. If not, build your React app using the appropriate command. Open your terminal or command prompt. Navigate to the root directory of your React static build folder. Run the following command to serve your build folder using the serve CLI: serve build -p 9000 This command will start a server and serve the files from the build folder on port 9000. Serving the Build Folder with SSL Make sure you have the SSL certificate and key files ready. If not, generate or obtain them and place them in a folder (e.g., certificates ) within your project directory. Open your terminal or command prompt.

During the development process, it's often necessary to showcase the progress made on a local development server to clients or stakeholders. However, local servers are typically only accessible on your machine or local network. In this blog post, we'll explore how you can use ngrok to share your local development server with clients for easy testing and feedback. Step 1: Install ngrok Ngrok is a powerful tool that creates a secure tunnel to expose your local server to the internet. To get started, head over to the ngrok website and sign up for a free account. Once signed in, download and install ngrok for your operating system. Step 2: Start Your Local Development Server Before using ngrok, make sure your local development server is up and running on the desired port. For example, if you're using Node.js and Express, you might have a server listening on port 3000. const express = require('express'); const app = e

In this ultimate tutorial, we'll walk you through the process of deploying a Create React App on Netlify. Netlify is a powerful platform for hosting static websites and provides an easy way to deploy and manage your React applications. Step 1: Create a React App First, make sure you have Create React App installed globally on your machine: npm install -g create-react-app Then, create a new React app: npx create-react-app my-app Step 2: Configure Netlify Next, sign up for a Netlify account and create a new site. Connect your site to your GitHub repository where your Create React App app is hosted. Step 3: Set up Build Settings In your Netlify site settings, navigate to the "Build & Deploy" section. Set the following build settings: Build command: npm run build Publish directory: build/ Step 4: Deploy to Netlify Install the Netlify CLI globally on your machine: npm install -g netlify-cli

One excellent option for hosting your React app is GitHub Pages. It allows you to deploy your application directly from your GitHub repository, making it accessible to users worldwide. In this blog post, we will walk you through the process of using GitHub Pages to host your React app. So, let's get started! Step 1: Create a React App Assuming you have Node.js and npm installed on your machine, begin by creating a new React application using Create React App. Open your terminal and run the following command: npx create-react-app my-app This command creates a new directory named "my-app" with the basic structure of a React application. Step 2: Set Up a GitHub Repository Navigate to GitHub (github.com) and create a new repository. Give it a name, add an optional description, and choose any additional settings you prefer. Ensure that the repository is public so that it can be accessed through GitHub Pages. Step 3: Connect Your Local React App to the Gi

In this blog post, we will learn how to customize the Spring Boot banner using the patorjk.com website. Step 1: Generate Custom Banner Go to the patorjk.com website and enter the desired text for your custom banner. You can choose from different font styles and designs. Step 2: Copy the Banner Text Once you are satisfied with the custom banner design, copy the generated text from the website. Step 3: Customize Spring Boot Banner Open your Spring Boot project and navigate to the src/main/resources directory. Create a new file called banner.txt if it doesn't exist already. Paste the copied banner text into the banner.txt file and save it. Step 4: Run the Spring Boot Application Start your Spring Boot application, and you will see the custom banner displayed in the console during the startup process. Customizing the Spring Boot banner allows you to ad

To integrate Swagger with a Spring Boot project, you can follow the steps outlined below. Unfortunately, as an AI text-based model, I cannot browse the internet or generate HTML content directly. However, I can provide you with the necessary steps to integrate Swagger and code snippets in a structured manner. Step 1: Add Swagger Dependencies Include the necessary dependencies in your Spring Boot project's pom.xml file: <dependencies> <!-- Other dependencies --> <dependency> <groupId>io.springfox</groupId> <artifactId>springfox-boot-starter</artifactId> <version>3.0.0</version> </dependency> </dependencies> Step 2: Configure Swagger Create a configuration class to enable Swagger and customize its settings. Here's an example: import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import springfox.documentation.bu

Spring Data REST is a powerful framework that allows you to quickly and easily build RESTful APIs using Spring Data. With Spring Data REST, you can expose your data model as a RESTful web service, complete with CRUD operations and pagination support, without writing any custom controller code. In this blog post, we'll take a closer look at Spring Data REST and explore how you can use it to build powerful APIs that are easy to consume. Getting Started with Spring Data REST To get started with Spring Data REST, you'll need to add the spring-boot-starter-data-rest dependency to your Spring Boot project. Once you've added the dependency, Spring Boot will automatically create a RESTful web service for your data model. For example, if you have a Customer entity in your data model, Spring Data REST will automatically create endpoints for creating, reading, updating, and deleting customers. You can access these endpoints using HTTP requests, such as

In a Spring Boot project, Hibernate Validators can be used to validate data in forms or input fields, ensuring that the data entered by the user is in the correct format and meets specific criteria. Hibernate Validators can be easily integrated into a Spring Boot project by following a few simple steps. Adding Hibernate Validators to a Spring Boot Project To add Hibernate Validators to a Spring Boot project, you will need to add the following dependency to your build.gradle or pom.xml file: <dependency> <groupId>org.hibernate.validator</groupId> <artifactId>hibernate-validator</artifactId> <version>6.2.0.Final</version> </dependency> After adding the dependency, you will need to annotate your entity classes with validation constraints. Hibernate Validators provides a wide range of constraints that you can use to validate your entities, such as @NotNull, @NotEmpty, @Size, @Email, @Pattern, and many more.

In distributed systems, failures are inevitable. Network errors, server downtime, and other issues can disrupt communication between microservices, causing errors and failures. To address this, Spring Cloud provides a built-in retry mechanism that allows you to automatically retry failed requests to a remote service. How Does It Work? Spring Cloud's retry mechanism intercepts HTTP requests sent from one microservice to another. If a request fails, the mechanism automatically retries the request a configurable number of times, with a configurable delay between each retry. To use Spring Cloud's retry mechanism, you need to add the spring-retry library to your project. This library provides annotations that you can use to annotate methods that you want to be retried in case of failure. Here's an example of how to use the @Retryable annotation: @Retryable(maxAttempts = 3, value = { HttpClientErrorException.class }) public String getRemoteData() { // send

Java's Object Class and Its Methods In Java, all classes inherit from the Object class, which provides several useful methods that are available to all classes. Understanding these methods is essential for writing effective and efficient Java code. In this article, we'll take a closer look at the Object class and its methods. The Object Class The Object class is a fundamental part of the Java language and is the superclass of all other classes. It provides several methods that are available to all classes. Here are some of the most commonly used methods: equals() The equals() method is used to compare two objects for equality. By default, it checks whether two objects are the same instance, but you can override it to define custom equality rules. Here's an example: public class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; }

In Java, the equals() and hashCode() methods are used to compare objects and to generate unique hash codes for objects, respectively. By default, these methods are inherited from the Object class, which means that they compare objects based on their memory addresses. However, in many cases, we need to compare objects based on their contents rather than their memory addresses. To do so, we can provide our own implementations of equals() and hashCode() methods in our custom classes. Example Class Let's start with an example class that we will use throughout this blog. Suppose we have a class called Person that represents a person's name and age. Here's the class definition: public class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public int getAge() { return age; } } Imp

Swagger is a powerful tool for documenting APIs. It allows developers to easily create and share documentation for their APIs, making it easier for other developers to understand how to use their APIs. In this article, we'll explore how to use Swagger with Spring Boot. What is Swagger? Swagger is an open-source software framework that helps developers design, build, document, and consume RESTful web services. It provides a standard format for describing REST APIs, which allows developers to quickly and easily understand how to use an API without needing to read through lengthy documentation. How to use Swagger with Spring Boot Spring Boot provides built-in support for Swagger, which makes it easy to integrate Swagger into your Spring Boot application. To get started, you'll need to add the following dependencies to your Spring Boot project: <dependency> <groupId>io.springfox</groupId> <artifactId>springfox-swagger2</artifactId>

One common error you may encounter when customizing JSON output in a Spring Boot application is the Infinite Recursion (StackOverflowError) error. This occurs when you have circular references between objects, where Object A refers to Object B, and Object B refers back to Object A. When Jackson attempts to serialize these objects to JSON, it gets stuck in an infinite loop, resulting in a StackOverflowError. One way to fix this error is to use the @JsonIgnore annotation to exclude one of the circularly-referenced fields from the JSON output. If you're working on a Spring Boot project that uses JSON serialization to handle data, you may have come across a scenario where you don't want certain fields to be included in the serialized JSON output. This is where the @JsonIgnore annotation comes in handy. The @JsonIgnore annotation is a part of the Jackson JSON library, which is the default JSON library used by Spring Boot. When applied to a field in a Java class, it t

Enabling CORS in a Spring Boot Application Cross-Origin Resource Sharing (CORS) is a security feature implemented by web browsers that restricts web pages from making requests to a different domain than the one that served the web page. This is a common issue when building Single Page Applications (SPAs) or consuming RESTful APIs from different domains. In this blog post, we'll look at how to enable CORS in a Spring Boot application. Step 1: Add CorsFilter Bean The first step to enabling CORS in a Spring Boot application is to create a CorsFilter bean. Here's how: import org.springframework.beans.factory.annotation.Value; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.web.cors.CorsConfiguration; import org.springframework.web.cors.UrlBasedCorsConfigurationSource; import org.springframework.web.filter.CorsFilter; import java.util.Arrays; @Configuration publi

Spring Boot is a popular framework for building web applications, and it provides a convenient way to receive HTTP requests using the @PostMapping annotation in its controllers. When processing a post request, it's common to use a Data Transfer Object (DTO) class to map the request data to Java objects. However, it's also possible to receive post requests without a DTO class and instead use a Map object to represent the request data. In this blog, we will explore how to receive post requests using a Map object in a Spring Boot controller and discuss some of the advantages and disadvantages of this approach. Handling a Post Request in a Spring Boot Controller First, let's start with a simple example of how to handle a post request in a Spring Boot controller using a DTO class. Consider the following DTO class: public class UserDto { private String name; private int age; public String getName() { return name; } public void set

  Project Lombok is a popular Java library that can help developers reduce the amount of boilerplate code they write. This library includes a set of annotations that can generate getters, setters, constructors, and other methods automatically, making code shorter and more concise. In this blog post, we will discuss some of the key features of Project Lombok, how it can help developers, and why it has become so popular among Java developers. What is Project Lombok? Project Lombok is a Java library that can help developers reduce the amount of boilerplate code they write. This library provides a set of annotations that can generate code automatically, such as getters, setters, constructors, and other methods. For example, suppose we have a Java class with two private fields: name and age. In a typical Java class, we would need to write a constructor to initialize these fields, getters and setters to access them, and perhaps some other methods. However, with Project Lombok, we can use the