Fullstack Java: Building Chat Applications with Spring Boot and WebSocket

In the modern web, real-time communication has become a critical feature, whether it’s for chat apps, notifications, or live data feeds. For fullstack Java developers, Spring Boot combined with WebSocket provides a robust and scalable way to build real-time applications. In this blog, we’ll explore how to build a basic chat application using Spring Boot and WebSocket, demonstrating how to enable real-time messaging between clients.

Why Use WebSocket for Chat?

Traditional HTTP requests follow a request-response model, which means the server can only respond after receiving a request. This model is inefficient for real-time applications like chat, where the server needs to push updates to clients instantly.

WebSocket is a protocol that provides full-duplex communication over a single TCP connection. It allows servers to send messages to clients without being explicitly asked, making it perfect for chat apps.

Setting Up Spring Boot with WebSocket

Step 1: Create a Spring Boot Project

Use Spring Initializr and add the following dependencies:

• Spring Web
• WebSocket
• Generate the project and open it in your IDE.

Step 2: Configure WebSocket

Create a configuration class to enable WebSocket support:

java

import org.springframework.context.annotation.Configuration;

import org.springframework.messaging.simp.config.MessageBrokerRegistry;

import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;

import org.springframework.web.socket.config.annotation.StompEndpointRegistry;

import org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurer;

@Configuration

@EnableWebSocketMessageBroker

public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

    @Override

    public void registerStompEndpoints(StompEndpointRegistry registry) {

        registry.addEndpoint("/ws").withSockJS();

    }

    @Override

    public void configureMessageBroker(MessageBrokerRegistry registry) {

        registry.setApplicationDestinationPrefixes("/app");

        registry.enableSimpleBroker("/topic");

    }

}

This sets up a WebSocket endpoint /ws and a message broker for routing messages.

Step 3: Create Message Models

java

public class ChatMessage {

    private String sender;

    private String content;

    private String type; // e.g., "CHAT", "JOIN", "LEAVE"

    

    // Getters and setters

}

Step 4: Create a Controller

java

import org.springframework.messaging.handler.annotation.MessageMapping;

import org.springframework.messaging.handler.annotation.SendTo;

import org.springframework.stereotype.Controller;

@Controller

public class ChatController {

    @MessageMapping("/chat.send")

    @SendTo("/topic/public")

    public ChatMessage sendMessage(ChatMessage message) {

        return message;

    }

}

Messages sent to /app/chat.send will be broadcasted to /topic/public.

Step 5: Create Frontend to Connect WebSocket

You can use plain JavaScript or a frontend framework like React or Angular. Here's a basic example with JavaScript and SockJS:

html

<script src="https://cdn.jsdelivr.net/npm/sockjs-client/dist/sockjs.min.js"></script>

<script src="https://cdn.jsdelivr.net/npm/stompjs/lib/stomp.min.js"></script>

<script>

    var socket = new SockJS('/ws');

    var stompClient = Stomp.over(socket);

    stompClient.connect({}, function () {

        stompClient.subscribe('/topic/public', function (message) {

            console.log(JSON.parse(message.body));

        });

        stompClient.send("/app/chat.send", {}, JSON.stringify({

            sender: "Alice",

            content: "Hello!",

            type: "CHAT"

        }));

    });

</script>

Final Thoughts

Building a chat application with Spring Boot and WebSocket is straightforward and scalable. This combination allows fullstack Java developers to create real-time features with minimal complexity. The WebSocket protocol ensures efficient, low-latency communication, while Spring Boot simplifies server-side development.

Whether you’re creating a chat app, live notifications, or multiplayer games, WebSocket with Spring Boot is a solid choice for real-time communication in fullstack Java projects.

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