How do you create a WebSocket handler in Spring Boot?

Table of Contents

• Introduction
• Steps to Create a WebSocket Handler in Spring Boot
  • 1. Add WebSocket Dependencies
  • 2. Create the WebSocket Handler
  • 3. Configure WebSocket in Spring Boot
  • 4. Create a WebSocket Client
  • 5. Test the WebSocket Handler
• Conclusion

Introduction

In Spring Boot, WebSocket is a powerful protocol that enables full-duplex, real-time communication between the client and the server. By creating a WebSocket handler, you can manage the flow of messages and handle events like connection establishment, message reception, and disconnection. This guide will walk you through creating a WebSocket handler in Spring Boot and integrating it into your application for real-time communication.

Steps to Create a WebSocket Handler in Spring Boot

1. Add WebSocket Dependencies

First, ensure that you have the necessary dependencies in your pom.xml (for Maven) or build.gradle (for Gradle) to enable WebSocket support in your Spring Boot project.

For Maven:

For Gradle:

2. Create the WebSocket Handler

The WebSocket handler in Spring Boot is responsible for handling WebSocket messages. You create a class that implements WebSocketHandler and override its methods to define how the WebSocket connection should behave.

Here’s an example of creating a custom WebSocket handler that handles incoming text messages.

3. Configure WebSocket in Spring Boot

Now, you need to configure the WebSocket handler and register it with Spring Boot. This is done in a configuration class that implements WebSocketConfigurer.

• **/ws**: The endpoint that clients will use to connect to the WebSocket.
• **setAllowedOrigins("*")**: This allows cross-origin requests to the WebSocket endpoint. You can restrict this by specifying the allowed domains.

4. Create a WebSocket Client

Now, let’s create a simple WebSocket client that can connect to the server and send messages. You can use JavaScript for the client-side WebSocket communication.

5. Test the WebSocket Handler

• Run your Spring Boot application.
• Open the HTML client in a browser.
• You should see messages exchanged between the client and server over the WebSocket connection. The server will respond with "Hello, you sent: [message]".

Conclusion

Creating a WebSocket handler in Spring Boot involves implementing the WebSocketHandler interface, configuring it in a WebSocket configuration class, and registering it to an endpoint. This approach enables real-time communication between the client and server, allowing for efficient message exchange without the need for polling or frequent HTTP requests. By following these steps, you can set up WebSocket communication in your Spring Boot applications for use cases like live chats, notifications, and more.