WebSocket + Spring boot web application example

Hello everyone, Today we will learn how to develop a Simple Spring Boot web application with WebSocket

Why WebSocket?

We already know traditional HTTP requests are unidirectional and heavy.But WebSocket is bi-directional.The initial connection is using HTTP, then this connection gets upgraded to a socket-based connection. This single connection is then used for all future communication.The WebSocket message data exchange is much lighter compared to HTTP
Following technologies stack being used:

  • Spring Boot 2.1.4.RELEASE
  • Spring 5.1.6.RELEASE 
  • JDK 1.8
  • Eclipse Oxygen
  • Bootstrap
  • Thymeleaf
  • WebSocket

User Interface


Project Structure

Pom.xml[maven]

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.4.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<artifactId>springboot-websocket-example</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>springboot-websocket-example</name>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-websocket</artifactId>
</dependency>
<dependency>
<groupId>org.json</groupId>
<artifactId>json</artifactId>
<version>20171018</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<groupId>com.knowledgefactory</groupId>
<description>springboot-websocket-example</description>
</project>

SocketConfig.class

package com.knowledgefactory;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;

@Configuration
@EnableWebSocket
public class SocketConfig implements WebSocketConfigurer {
public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
registry.addHandler(new TextHandler(), "/getMessage");
}
}

TextHandler.class

package com.knowledgefactory;

import java.io.IOException;
import org.json.JSONException;
import org.json.JSONObject;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

@Component
public class TextHandler extends TextWebSocketHandler {
@Override
public void handleTextMessage(WebSocketSession session, TextMessage message)
throws InterruptedException, IOException, JSONException {
String payload = message.getPayload();
JSONObject jsonObject = new JSONObject(payload);
session.sendMessage(new TextMessage("Your message:" + jsonObject.get("user")));
}
}

KnowledgefactorydemoApplication.class(Spring Boot)

package com.knowledgefactory;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

index.html

<!DOCTYPE html>
<html>

<head>
<title>WebSocket Chat Application</title>
<link href="/bootstrap.min.css" rel="stylesheet">
<script src="/jquery.min.js"></script>
<script src="/main.js"></script>
<script src="/bootstrap.min.js"></script>
</head>

<body>
<div class="container">
<br> <br> <br>
<div class="row">
<div class="col-md-2"></div>
<div class="col-md-8">
<form class="form-inline">
<div class="form-group">
<label for="connect">Spring Boot socket programming
example:</label>
<button class="btn btn-success" id="connect" type="button">Start
</button>
<button class="btn btn-danger" id="disconnect" type="button" disabled="disabled">End</button>
</div>
</form>
</div>
<div class="col-md-2"></div>
</div>
<br> <br> <br>
<div class="row">
<div class="col-md-2">
<table id="chat">
<thead>
<tr>
<th>Welcome,Please enter your message</th>
</tr>
</thead>
</table>
</div>
<div class="col-md-2"></div>
<div class="col-md-6">
<form>
<div class="form-group">
<textarea class="form-control" rows="5" id="user" placeholder="Write your message here..."
required></textarea>
</div>
<button class="btn btn-primary" id="send" type="submit">Send</button>
</form>
</div>
<div class="col-md-2"></div>
<br> <br>
</div>
<div class="raw">
<div class="col-md-2">
<table id="response">
<thead>
<tr>
<th>Your Message</th>
</tr>
</thead>
</table>
</div>
<div class="col-md-2"></div>
<div class="col-md-8">
<form>
<div class="form-group">
<textarea id="helloworldmessage" class="form-control" rows="15" placeholder="Your Message"
required></textarea>
</div>
</form>
</div>
</div>
</div>
</body>

</html>

main.js
var ws;
function setConnected(connected) {
$("#connect").prop("disabled", connected);
$("#disconnect").prop("disabled", !connected);
}
function connect() {
ws = new WebSocket('ws://localhost:8080/getMessage');
ws.onmessage = function (data) {
helloWorld(data.data);
}
setConnected(true);
}
function disconnect() {
if (ws != null) {
ws.close();
}
setConnected(false);
console.log("Websocket is in disconnected state");
}
function sendData() {
var data = JSON.stringify({
'user': $("#user").val()
})
ws.send(data);
}
function helloWorld(message) {
$("#helloworldmessage").append("\n " + message + "");
}
$(function () {
$("form").on('submit', function (e) {
e.preventDefault();
});
$("#connect").click(function () {
connect();
});
$("#disconnect").click(function () {
disconnect();
});
$("#send").click(function () {
sendData();
});
});

Run
$ mvn spring-boot:run

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