Introduction Here I am going to show you how to write Junit test for Spring Boot main class. A class having main method in Spring boot application is called main class and the purpose of this class is to deploy the application into embedded Tomcat server without configuring deployment descriptor or generating war file for…

Posted in Junit Spring Boot

How To Write Junit Test For Spring Boot Main Class

Introduction In this example I will show you how to convert entity class to DTO (Data Transfer Object) class and DTO class to entity class using MapStruct. So, MapStruct will map entity class to DTO class or vice versa. This example will test both from RESTful webservices and standalone main class. Spring Boot provides CommandLineRunner…

Posted in Spring Boot Spring JPA

Spring Boot Data JPA Entity DTO Mapping Using MapStruct

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

Introduction Servlet filters are Java classes that are invoked at pre and post processing of requests. So filters are used to intercept requests from clients before they access requests at backend (server). to manipulate responses from server before they are sent back to the client RequestContextFilter is also a servlet filter that extends OncePerRequestFilter that…

Posted in Spring Boot

Spring Boot Filters Example

Introduction The ability of hasPermission() method in Spring Boot Security applications is to determine the accessibility of a particular user for the application. The permission of an access can be read, write, etc. So, a particular user has defined set of access permission by which a user can perform certain activities in the application. The…

Posted in Spring Boot Spring JPA Spring Security

PreAuthorize HasPermission Security Using Spring Boot Data JPA

Problem Recently while I was working with Spring Security in recent versions of Spring Boot framework (2.6.6/2.6.7), I was getting the following error (Requested bean is currently in creation: Is there an unresolvable circular reference?):

Posted in Spring Boot Spring Security

Error bean securityConfig: unresolvable circular reference

Table of Contents Introduction Where is @PreAuthorize applicable? Prerequisites Project Setup MySQL Table Data Application Config Entity Classes Repository Interfaces Service Class REST Controller Class Security Config Spring Boot Main Class Testing Spring Security – PreAuthorize hasRole Source Code Introduction PreAuthorize hasRole Spring security will determine whether a user can invoke a method or not…

Posted in Spring Boot Spring JPA Spring Security

PreAuthorize HasRole Security Using Spring Boot Data JPA

Table of Contents Introduction Prerequisites Project Setup MySQL Table DataSource Config Entity Class Repository Interface Service Class Spring Web Controller Spring Boot Main Class UI (User Interface) Testing Multi Steps Form Source Code Introduction In this example I am going to show you how to build multisteps form using Spring Boot thymeleaf jquery. Multi steps…

Posted in jQuery Spring Boot

Spring Boot Thymeleaf jQuery MultiSteps Form

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

Table of Contents Introduction Why do you want to connect to multiple database Prerequisites Project Setup Application Properties DataSource Configurations DAO Class Source Code Introduction Here I am going to show you how to connect to Oracle data source using JDBC LDAP URL. I am going to create multiple data sources for connecting to multiple…

Posted in Database Spring Boot Spring JDBC

Connecting To Multiple Oracle Data Sources Using JDBC LDAP URLs

Table of Contents Introduction What Is Dead Letter Queue Prerequisites Project Setup Application Properties Custom Exception Producer or Sender Consumer or Receiver Config Class Spring Boot Main Class Testing RabbitMQ Dead Letter Queue Source Code Introduction In this example I am going to show you how to retry the failed messages in RabbitMQ message broker….

Posted in RabbitMQ Spring Boot

Spring RabbitMQ Retry And Error Handling Example

Table of Contents Introduction Prerequisites Angular Project Settings Gradle Properties Spring Boot Project Build App Testing Angular Spring Boot Integration Source Code Introduction In this tutorial I will show you how to integrate Angular into Spring Boot using Gradle build tool. So, let’s say you have two different projects – Angular application and Spring Boot…

Posted in Angular Gradle Spring Boot

Integrate Angular into Spring Boot using Gradle