Hedwig

Proof-of-concept application to send emails to user on event occurence

Click Here To Use Running Application

Technologies Used

• Java Spring Boot
• JavaMail-API
• Spring Events
• Apache Freemarker
• JPA/H2 in-memory database
• Lombok
• Open-API (swagger-ui)
• Bootstrap-Email Editor

Spring Events

• Reference Article
• Event classes will represent an event for which a mail has to be sent (account-creation-event in this context can be anything depending on business logic)
• A listener class that listens to the above created event and executes code whenever the above event occures
• A publisher will publish the event (notify that event has occurred) and can be injected in the service layer
• Listener method to be executed asynchronously (recommended)

Main classes (Drag to new window)

• Email-Service (to send emails to provided email-id with provided template and subject)
• Account Creation Event
• Account Creation Event Listener (receives userCreationRequestDto as input and sends mail to provided email-id asynchronously)
• User Service (class that creates user account in the system and publishes that AccountCreationEvent has occurred)

Bootstrap Email

• HTML for emails is slightly different from HTML for web
• Copy the HTML generated from bootstrap email editor (right part of screen) to a .ftl file under src/main/resources/templates (configured in FreemarkerConfiguration.class)
• account-creation-success.ftl in templates folder will be generated to the below image
• ${emailId} and ${fullName} will be converted to provided emailId and fullname with the help of apache freemarker

Local Setup

• Install Java 15
• Install Maven

Recommended way is to use sdkman for installing both maven and java

Go to application.properties and configure your email and app password (diffrent from regular passwords)

spring.mail.username = <EMAIL-ID-HERE>
spring.mail.password = <PASSWORD-HERE>

Run the below commands in the core

mvn clean install

mvn spring-boot:run

server port is configured to 9090 and base-url to /hedwig which can be changed in application.properties file

Go to the below url to view swagger-ui (API docs)

http://localhost:9090/hedwig/swagger-ui.html

Run Tests

mvn test