Spring Boot Starter WebSocket Example: Everything You Need to Know

WebSocket is a protocol that enables two-way communication between a client and a server. It provides a persistent connection that allows real-time communication between web applications. Spring Boot, on the other hand, is a popular Java-based framework that enables developers to create standalone, production-grade web applications with minimal configuration. Combining these two technologies can make it easier for developers to create real-time web applications. In this article, we will explore the Spring Boot Starter WebSocket example in detail.

What is Spring Boot Starter WebSocket?

Spring Boot Starter WebSocket is a module that provides support for WebSocket-based communication in Spring Boot applications. It includes an implementation of the WebSocket protocol, as well as a set of APIs that make it easier for developers to handle WebSocket connections and messages. With Spring Boot Starter WebSocket, developers can easily create real-time web applications that can handle multiple connections and messages simultaneously.

How to Use Spring Boot Starter WebSocket

Using Spring Boot Starter WebSocket is relatively easy. Here are the basic steps:

1. Add the Spring Boot Starter WebSocket dependency to your project.
2. Create a WebSocket configuration class that extends the AbstractWebSocketMessageBrokerConfigurer class.
3. Override the configureMessageBroker method to configure the message broker.
4. Override the registerStompEndpoints method to register the WebSocket endpoints.
5. Create a WebSocket controller to handle WebSocket messages.

We will go through each of these steps in detail.

Adding the Spring Boot Starter WebSocket Dependency

The first step is to add the Spring Boot Starter WebSocket dependency to your project. You can do this by adding the following dependency to your pom.xml file:

pom.xml

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-websocket</artifactId></dependency>

This will download and include the Spring Boot Starter WebSocket module in your project.

Creating a WebSocket Configuration Class

The next step is to create a WebSocket configuration class that extends the AbstractWebSocketMessageBrokerConfigurer class. This class is responsible for configuring the WebSocket message broker. Here’s an example:

WebSocketConfig.java

@Configuration@EnableWebSocketMessageBrokerpublic class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {@Overridepublic void configureMessageBroker(MessageBrokerRegistry config) {config.enableSimpleBroker("/topic");config.setApplicationDestinationPrefixes("/app");}@Overridepublic void registerStompEndpoints(StompEndpointRegistry registry) {registry.addEndpoint("/hello").withSockJS();}}

In this example, we have created a WebSocketConfig class that extends the AbstractWebSocketMessageBrokerConfigurer class. We have also annotated the class with the @Configuration and @EnableWebSocketMessageBroker annotations.

The configureMessageBroker method configures the message broker. In this example, we have enabled the simple broker and set the application destination prefixes.

The registerStompEndpoints method registers the WebSocket endpoints. In this example, we have registered the “/hello” endpoint and enabled SockJS support.

Creating a WebSocket Controller

The final step is to create a WebSocket controller that handles WebSocket messages. Here’s an example:

WebSocketController.java

@Controllerpublic class WebSocketController {@MessageMapping("/hello")@SendTo("/topic/greetings")public Greeting greeting(HelloMessage message) throws Exception {Thread.sleep(1000); // simulated delayreturn new Greeting("Hello, " + message.getName() + "!");}}

In this example, we have created a WebSocketController class that handles WebSocket messages. We have also annotated the class with the @Controller annotation.

The greeting method handles messages that are sent to the “/hello” endpoint. It takes a HelloMessage object as a parameter and returns a Greeting object. The @MessageMapping annotation maps the method to the “/hello” endpoint, and the @SendTo annotation specifies the destination of the response message.

Spring Boot Starter WebSocket Example: Code Walkthrough

Now that we have covered the basic steps for using Spring Boot Starter WebSocket, let’s walk through an example to see how it all fits together.

For this example, we will create a simple chat application that allows users to send and receive messages in real-time. Here’s the code:

ChatApplication.java

@SpringBootApplicationpublic class ChatApplication {public static void main(String[] args) {SpringApplication.run(ChatApplication.class, args);}}

This is the main class for our application. It is a standard Spring Boot application, with the @SpringBootApplication annotation that enables auto-configuration.

WebSocketConfig.java

@Configuration@EnableWebSocketMessageBrokerpublic class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {@Overridepublic void configureMessageBroker(MessageBrokerRegistry config) {config.enableSimpleBroker("/topic");config.setApplicationDestinationPrefixes("/app");}@Overridepublic void registerStompEndpoints(StompEndpointRegistry registry) {registry.addEndpoint("/chat").withSockJS();}}

This is the WebSocket configuration class. It extends the AbstractWebSocketMessageBrokerConfigurer class and overrides the configureMessageBroker and registerStompEndpoints methods.

The configureMessageBroker method enables the simple broker and sets the application destination prefixes. The registerStompEndpoints method registers the “/chat” endpoint and enables SockJS support.

ChatController.java

@Controllerpublic class ChatController {@MessageMapping("/chat.sendMessage")@SendTo("/topic/public")public ChatMessage sendMessage(@Payload ChatMessage chatMessage) {return chatMessage;}@MessageMapping("/chat.addUser")@SendTo("/topic/public")public ChatMessage addUser(@Payload ChatMessage chatMessage,SimpMessageHeaderAccessor headerAccessor) {headerAccessor.getSessionAttributes().put("username", chatMessage.getSender());return chatMessage;}}

This is the WebSocket controller class. It handles WebSocket messages and maps them to specific endpoints.

The sendMessage method handles messages that are sent to the “/chat.sendMessage” endpoint. It takes a ChatMessage object as a parameter and returns the same object. The @MessageMapping annotation maps the method to the “/chat.sendMessage” endpoint, and the @SendTo annotation specifies the destination of the response message.

The addUser method handles messages that are sent to the “/chat.addUser” endpoint. It takes a ChatMessage object and a SimpMessageHeaderAccessor object as parameters. It sets the username in the session attributes and returns the ChatMessage object. The SimpMessageHeaderAccessor object is used to get and set session attributes.

ChatMessage.java

public class ChatMessage {private MessageType type;private String content;private String sender;public enum MessageType {CHAT,JOIN,LEAVE}// getters and setters}

This is a simple Java class that represents a chat message. It has three fields: type, content, and sender. It also has an enum called MessageType that represents the type of message.

FAQ

What is WebSocket?

WebSocket is a protocol that enables two-way communication between a client and a server. It provides a persistent connection that allows real-time communication between web applications.

What is Spring Boot?

Spring Boot is a popular Java-based framework that enables developers to create standalone, production-grade web applications with minimal configuration.

What is Spring Boot Starter WebSocket?

Spring Boot Starter WebSocket is a module that provides support for WebSocket-based communication in Spring Boot applications.

How do you use Spring Boot Starter WebSocket?

To use Spring Boot Starter WebSocket, you need to add the Spring Boot Starter WebSocket dependency to your project, create a WebSocket configuration class that extends the AbstractWebSocketMessageBrokerConfigurer class, override the configureMessageBroker method to configure the message broker, override the registerStompEndpoints method to register the WebSocket endpoints, and create a WebSocket controller to handle WebSocket messages.

What are some examples of real-time web applications?

Some examples of real-time web applications include chat applications, stock tickers, and multiplayer games.

What are some advantages of real-time web applications?

Real-time web applications provide a more engaging user experience, as users can see changes in real-time. They also enable faster communication and collaboration between users.

Conclusion

Spring Boot Starter WebSocket is a powerful tool for creating real-time web applications. By combining the Spring Boot framework with the WebSocket protocol, developers can easily create applications that provide a more engaging user experience and enable faster communication and collaboration between users. With the steps and examples outlined in this article, you should be well on your way to creating your own real-time web application using Spring Boot Starter WebSocket.