Introduction In this example I am going to show you how to use Spring’s MultiValueMap in REST API. This MultiValueMap is similar to the Jersey’s MultivaluedMap. A MultiValueMap<K, V> or MultivaluedMap<K, V> is a map of key-values pairs. Each key can have zero or more values, where K – the type of keys maintained by this map and V – the…

Posted in Spring Boot Spring REST

Spring Boot REST API MultiValueMap Example

Table of Contents Introduction Prerequisites Project Setup MySQL Table Application Properties Entity Class Repository Interface Service Class REST Controller Spring Boot Main Class Testing Hazelcast Caching Java Config for Hazelcast Source Code Introduction In this tutorial I am going to show you an example on caching using hazelcast in Spring Boot REST APIs. The cache…

Posted in Spring Boot Spring REST

Caching Using Hazelcast In Spring Boot REST API

Introduction Here I am going to tell you how to use proxy server and timeout with Spring Boot RestTemplate API. If you are running your application behind a proxy server then you need to connect to REST API through proxy server and without proxy server connection you may face connection timeout error or other errors. Remember if…

Posted in Spring Boot Spring REST

Spring RestTemplate With Auth Token, Proxy and Timeout

Introduction In this tutorial I am going to show you how to build Spring Boot Angular CRUD Application. CRUD is an acronym and stands for Create, Read, Update and Delete operations performed through an application or APIs. Using Spring Boot application I will build REST APIs which will be used to perform CRUD operations on…

Posted in Angular Spring Boot Spring JPA Spring REST

Angular Spring Boot REST API CRUD Example

Introduction In this example I am going to show you Spring Security Pre-authentication hasrole with Spring Data JPA. In my another example I had shown the similar example on Spring Security Pre-Authentication with Spring JDBC Template. There are situations where you want to use Spring Security for authorization, but the user has already been reliably…

Posted in Spring Boot Spring REST Spring Security

Spring Security Pre-Authentication with Spring Data JPA

Introduction Here I am going to build a system to log online user activity in Spring Boot applications using HandlerInterceptor interface. As an application owner you may want to track your user activities, such as, which page they are accessing, from where requests were made to your application, from which pages to which pages they…

Posted in Spring Boot Spring JPA Spring REST

How To Log Online User Activity In Spring Boot Applications

Introduction In this tutorial I am going to show you how to call Spring REST APIs concurrently using Java CompletableFuture. So basically REST service APIs will be invoked parallelly and in parallel execution the response time will be very less. I am going to show you how to call REST APIs concurrently using Java 8…

Posted in Microservices Spring Boot Spring REST

How To Call Spring REST APIs Concurrently using Java CompletableFuture

Table of Contents Introduction Prerequisites Download Large File Using WebClient Using RestTemplate Testing the APplication Source Code Introduction Here in this tutorial I am going to show you how to download large file using Spring REST API. Generally when you download a file, your file is stored into file system or you load it into…

Posted in Spring Boot Spring REST

Download Large File using Spring REST API

Introduction Here in this tutorial I am going to show you how to use AJAX technique using jQuery with Spring Boot application to check user availability instantly without refreshing the web page. I am going to use Thymeleaf template in Spring Boot application. I will use Spring REST to create REST API endpoint which will…

Posted in AJAX jQuery Spring Boot Spring REST

Spring Boot AJAX jQuery to check User Availability Instantly

Table of Contents Introduction Authentication/Authorization Flow Prerequisites Project Setup Authentication Service Spring Cloud Gateway Testing JWT Auth in Spring Cloud Gateway Source Code Introduction In this tutorial I am going to show you an example on Spring Cloud Gateway Security with JWT. JSON Web Tokens (JWT) are an open, industry standard RFC 7519 method for…

Posted in Spring Boot Spring Cloud Spring REST Spring Security Spring WebFlux

Spring Cloud Gateway Security with JWT (JSON Web Token)

In this tutorial I am going to discuss about what is Whitelabel Error Page and how to deal with Whitelabel Error Page in Spring Boot applications. Spring boot allows you to setup a Spring based application with minimal configurations. Spring MVC applications provide no default (fall-back) error page out of the box but Spring Boot…

Posted in Spring Boot Spring REST

How to deal with Whitelabel Error Page in Spring Boot Applications

Here in this example I am going to show you how to allow users for OAuth2 SSO (Single Sign On) using AWS (Amazon Web Services) Cognito. I had explained how to do OAuth2 Single Sign On using Spring Boot and GitHub account. Here I am going to use AWS Cognito. You can use any other…

Posted in AWS Spring Boot Spring REST Spring Security

Spring Boot OAuth2 SSO Example with AWS Cognito