SockJS 是一个浏览器上运行的 JavaScript 库，如果浏览器不支持 WebSocket，该库可以模拟对 WebSocket 的支持，实现浏览器和 Web 服务器之间低延迟、全双工、跨域的通讯通道【2】。

SockJS family:

• SockJS-client JavaScript client library
• SockJS-node Node.js server
• SockJS-erlang Erlang server
• SockJS-tornado Python/Tornado server
• SockJS-twisted Python/Twisted server
• vert.x Java/vert.x server

Work in progress:

• SockJS-ruby
• SockJS-netty
• SockJS-gevent (SockJS-gevent fork)
• pyramid-SockJS
• wildcloud-websockets
• SockJS-cyclone
• wai-SockJS
• SockJS-perl
• SockJS-go

public interface WebSocketMessage<T> {/*** Returns the message payload. This will never be {@code null}.*/T getPayload();/*** Return the number of bytes contained in the message.*/int getPayloadLength();/*** When partial message support is available and requested via* {@link org.springframework.web.socket.WebSocketHandler#supportsPartialMessages()},* this method returns {@code true} if the current message is the last part of the* complete WebSocket message sent by the client. Otherwise {@code false} is returned* if partial message support is either not available or not enabled.*/boolean isLast();}

    /*** Start the websocket connection. If already connected, the method has no impact.*/@Overridepublic final void start() {synchronized (this.lifecycleMonitor) {if (!isRunning()) {startInternal();}}}protected void startInternal() {synchronized (lifecycleMonitor) {if (logger.isDebugEnabled()) {logger.debug("Starting " + this.getClass().getSimpleName());}this.isRunning = true;openConnection();}}

protected abstract void openConnection();

    private final WebSocketContainer webSocketContainer;private AsyncListenableTaskExecutor taskExecutor = new SimpleAsyncTaskExecutor();

    public StandardWebSocketClient() {this.webSocketContainer = ContainerProvider.getWebSocketContainer();}

/*** Executes the given task, within a concurrency throttle* if configured (through the superclass's settings).* @see #doExecute(Runnable)*/@Overridepublic void execute(Runnable task) {execute(task, TIMEOUT_INDEFINITE);}/*** Executes the given task, within a concurrency throttle* if configured (through the superclass's settings).* <p>Executes urgent tasks (with 'immediate' timeout) directly,* bypassing the concurrency throttle (if active). All other* tasks are subject to throttling.* @see #TIMEOUT_IMMEDIATE* @see #doExecute(Runnable)*/@Overridepublic void execute(Runnable task, long startTimeout) {Assert.notNull(task, "Runnable must not be null");if (isThrottleActive() && startTimeout > TIMEOUT_IMMEDIATE) {this.concurrencyThrottle.beforeAccess();doExecute(new ConcurrencyThrottlingRunnable(task));}else {doExecute(task);}}/*** Template method for the actual execution of a task.* <p>The default implementation creates a new Thread and starts it.* @param task the Runnable to execute* @see #setThreadFactory* @see #createThread* @see java.lang.Thread#start()*/protected void doExecute(Runnable task) {Thread thread = (this.threadFactory != null ? this.threadFactory.newThread(task) : createThread(task));thread.start();}

@Overrideprotected ListenableFuture<WebSocketSession> doHandshakeInternal(WebSocketHandler webSocketHandler,HttpHeaders headers, final URI uri, List<String> protocols,List<WebSocketExtension> extensions, Map<String, Object> attributes) {int port = getPort(uri);InetSocketAddress localAddress = new InetSocketAddress(getLocalHost(), port);InetSocketAddress remoteAddress = new InetSocketAddress(uri.getHost(), port);final StandardWebSocketSession session = new StandardWebSocketSession(headers,attributes, localAddress, remoteAddress);final ClientEndpointConfig.Builder configBuilder = ClientEndpointConfig.Builder.create();configBuilder.configurator(new StandardWebSocketClientConfigurator(headers));configBuilder.preferredSubprotocols(protocols);configBuilder.extensions(adaptExtensions(extensions));final Endpoint endpoint = new StandardWebSocketHandlerAdapter(webSocketHandler, session);Callable<WebSocketSession> connectTask = new Callable<WebSocketSession>() {@Overridepublic WebSocketSession call() throws Exception {webSocketContainer.connectToServer(endpoint, configBuilder.build(), uri);return session;}};if (this.taskExecutor != null) {return this.taskExecutor.submitListenable(connectTask);}else {ListenableFutureTask<WebSocketSession> task = new ListenableFutureTask<WebSocketSession>(connectTask);task.run();return task;}}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(DelegatingWebSocketMessageBrokerConfiguration.class)
public @interface EnableWebSocketMessageBroker {}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(DelegatingWebSocketConfiguration.class)
public @interface EnableWebSocket {
}

<!DOCTYPE html>
<html>
<head><title>Hello WebSocket</title><script src="sockjs-0.3.4.js"></script><script src="stomp.js"></script><script type="text/javascript">var stompClient = null;function setConnected(connected) {document.getElementById('connect').disabled = connected;document.getElementById('disconnect').disabled = !connected;document.getElementById('conversationDiv').style.visibility = connected ? 'visible' : 'hidden';document.getElementById('response').innerHTML = '';}function connect() {var socket = new SockJS('/hello');stompClient = Stomp.over(socket);stompClient.connect({}, function(frame) {setConnected(true);console.log('Connected: ' + frame);stompClient.subscribe('/topic/greetings', function(greeting){showGreeting(JSON.parse(greeting.body).content);});});}function disconnect() {if (stompClient != null) {stompClient.disconnect();}setConnected(false);console.log("Disconnected");}function sendName() {var name = document.getElementById('name').value;stompClient.send("/app/hello", {}, JSON.stringify({ 'name': name }));}function showGreeting(message) {var response = document.getElementById('response');var p = document.createElement('p');p.style.wordWrap = 'break-word';p.appendChild(document.createTextNode(message));response.appendChild(p);}</script>
</head>
<body onload="disconnect()">
<noscript><h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websocket relies on Javascript being enabled. Please enableJavascript and reload this page!</h2></noscript>
<div><div><button id="connect" onclick="connect();">Connect</button><button id="disconnect" disabled="disabled" onclick="disconnect();">Disconnect</button></div><div id="conversationDiv"><label>What is your name?</label><input type="text" id="name" /><button id="sendName" onclick="sendName();">Send</button><p id="response"></p></div>
</div>
</body>
</html>

package hello;import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.simp.config.MessageBrokerRegistry;
import org.springframework.web.socket.config.annotation.AbstractWebSocketMessageBrokerConfigurer;
import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
import org.springframework.web.socket.config.annotation.StompEndpointRegistry;@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {@Overridepublic void configureMessageBroker(MessageBrokerRegistry config) {config.enableSimpleBroker("/topic");config.setApplicationDestinationPrefixes("/app");}@Overridepublic void registerStompEndpoints(StompEndpointRegistry registry) {registry.addEndpoint("/hello").withSockJS();}}