Introduction Here in this tutorial I will show you an example on how to test private methods using Junit framework. I am using Junit 5 framework to test the private method. Using Mockito framework you won’t be able to test private methods, but using PowerMock core API you will be able to test the private…

In this tutorial I am going to show you how lookup method injection works in Spring framework. You may face a situation where you need to inject prototype scoped bean into singleton scoped bean. For singleton scoped bean a new instance or object is created and the same is returned each time it is injected…

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…

Here I am going to build an application to show how to use Spring Cloud Bus. Let’s say you have multiple applications reading properties using Spring Cloud Config from centralized configuration files (for example, from Git repository). Spring Cloud Config is where you can have not only your all configurations centrally managed but also you…

In this example I am going to show you how to run multiple batch jobs parallelly in Spring Batch framework. Spring Batch is a lightweight, comprehensive batch framework designed to enable the development of robust batch applications vital for the daily operations of enterprise systems. Spring Batch provides reusable functions that are essential in processing…

In this tutorial I am going to show you an example on deploying Spring Boot application to Heroku cloud. I will create a basic CRUD application with Spring Boot Data JPA and PostgreSQL/MySQL technologies. I will first show you how to perform CRUD operations locally, then deploy the same application in the Heroku cloud with…

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…

Introduction Here I am going to show you an example on how to return different data formats from REST API using Spring Boot framework. You may have a requirement that you need to return multiple formats, such as XML, JSON, etc., from the REST response, then this example may help you. This example will return…

In this example I am going to show you how to mock an autowired field in Spring boot framework with Junit 5. When you use @Value annotation in Spring beans to read the value from properties file and later when you want to perform Junit test then you also need to pass value for this…

Spring Data JPA provides multiple ways of selecting or fetching data from database server and one of the ways is using @NamedQuery or @NamedQueries. @NamedQuery and @NamedQueries can be created using XML configuration, external properties file or using Java based annotation config. Spring Data JPA supports both JPQL and SQL native named queries. Here I…

I am going to show yo how to download PDF file from MySQL database using Spring Boot and iText library in Java programming language. Many applications require dynamic generation of PDF documents for reporting purpose, such as, generating statements for customers, readers buying online specific chapters of a book, etc. In my another tutorial I…

Here I am going to show you how to download excel file from MySQL using Spring framework. Generating excel report from MySQL database has few advantages over other file formats. Most of the people you are working with in your organization are familiar with excel file format, hence it needs a short learning curve. You…