WebSocket Client连接远程WebSocket Server

在这篇文章中，简单介绍了WebSocket的使用，客户端可以使用了JavaScript向服务发送请求，服务端也可以通过SimpMessagingTemplate 主动向客户端推送消息，实现服务器端与客户端的双向交互。
下面介绍客户端如何连接远程WebSocket Server并推送消息，参照gs-messaging-stomp-websocket中的TestCase，我们简单修改下代码

@Slf4j
public class StompClientTest {
    public static void main(String[] args) throws Exception {
        int port = 8898;
        SockJsClient sockJsClient;
        WebSocketStompClient stompClient;
        final WebSocketHttpHeaders headers = new WebSocketHttpHeaders();
        StompSession stompSession = null;

        {
            List transports = new ArrayList<>();
            transports.add(new WebSocketTransport(new StandardWebSocketClient()));
            sockJsClient = new SockJsClient(transports);
            stompClient = new WebSocketStompClient(sockJsClient);
            stompClient.setMessageConverter(new MappingJackson2MessageConverter());
        }

        final CountDownLatch latch = new CountDownLatch(1);

        final AtomicReference failure = new AtomicReference<>();

        TestSessionHandler handler = new TestSessionHandler(failure) {
            private StompSession stompSession;

            @Override
            public String getSomething() {
                return "something in main";
            }

            @Override
            public void afterConnected(final StompSession session, StompHeaders connectedHeaders) {

                session.subscribe("/topic/greetings", new StompFrameHandler() {
                    @Override
                    public Type getPayloadType(StompHeaders headers) {
                        return Greeting.class;
                    }

                    @Override
                    public void handleFrame(StompHeaders headers, Object payload) {
                        Greeting greeting = (Greeting) payload;
                        try {
                            log.info("{}", greeting.getContent());
                        } catch (Throwable t) {
                            failure.set(t);
                        } finally {
                            session.disconnect();
                            latch.countDown();
                        }
                    }
                });
                try {
                    session.send("/app/hello", new HelloMessage("message forwarded from '/app/hello'"));
                    session.send("/topic/greetings", new Greeting("message directly from '/topic/greetings'"));
                    this.stompSession = session;
                } catch (Throwable t) {
                    failure.set(t);
                    latch.countDown();
                }
            }

            public StompSession getStompSession() {
                return stompSession;
            }
        };

        stompClient.connect("ws://localhost:{port}/gs-guide-websocket", headers, handler, port);

        log.info("something is {}", handler.getSomething());
        while (!stompClient.isRunning()) {
            if ((stompSession = handler.getStompSession()) != null) {
                break;
            }
        }

        stompSession.send("/app/hello", new HelloMessage("message2 forwarded from '/app/hello'"));
        stompSession.send("/topic/greetings", new Greeting("message2 directly from '/topic/greetings'"));
        stompSession.send("/app/hello", new HelloMessage("message3 forwarded from '/app/hello'"));
        stompSession.send("/topic/greetings", new Greeting("message3 directly from '/topic/greetings'"));

        if (latch.await(30, TimeUnit.SECONDS)) {
            if (failure.get() != null) {
                throw new AssertionError("", failure.get());
            }
        } else {
            fail("Greeting not received!");
        }
    }


}

代码修改部分

this.stompSession = session;

获取StompSession

while (!stompClient.isRunning()) {
     if ((stompSession = handler.getStompSession()) != null) {
          break;
      }
}

WebSocket连接之后，我们将StompSession返回，之后便可以通过send方法向远程WebSocket Server发送消息。

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hello.StompClientTest
20:27:11.778 [main] DEBUG org.springframework.web.socket.sockjs.client.RestTemplateXhrTransport - Executing SockJS Info request, url=http://localhost:8898/gs-guide-websocket/info
20:27:11.825 [main] DEBUG org.springframework.web.client.RestTemplate - Created GET request for "http://localhost:8898/gs-guide-websocket/info"
20:27:11.856 [main] DEBUG org.springframework.web.client.RestTemplate - GET request for "http://localhost:8898/gs-guide-websocket/info" resulted in 200 (null)
20:27:11.872 [main] DEBUG org.springframework.web.socket.sockjs.client.WebSocketTransport - Starting WebSocket session on ws://localhost:8898/gs-guide-websocket/46/94ec7870e1e548b2bdb1a48780895e77/websocket
20:27:11.872 [main] DEBUG org.springframework.web.socket.client.standard.StandardWebSocketClient - Connecting to ws://localhost:8898/gs-guide-websocket/46/94ec7870e1e548b2bdb1a48780895e77/websocket
20:27:11.919 [main] INFO hello.StompClientTest - something is something in main
20:27:12.075 [SimpleAsyncTaskExecutor-1] DEBUG org.springframework.web.socket.sockjs.client.WebSocketClientSockJsSession - Processing SockJS open frame in WebSocketClientSockJsSession[id='94ec7870e1e548b2bdb1a48780895e77, url=ws://localhost:8898/gs-guide-websocket]
20:27:12.075 [SimpleAsyncTaskExecutor-1] DEBUG org.springframework.messaging.simp.stomp.DefaultStompSession - Connection established in session id=750c50a6-97cf-d7a3-d245-1a693cb7a6f3
20:27:12.263 [WebSocketClient-AsyncIO-2] INFO hello.StompClientTest - message directly from '/topic/greetings'
20:27:12.271 [WebSocketClient-AsyncIO-2] DEBUG org.springframework.web.socket.sockjs.client.WebSocketClientSockJsSession - Closing session with CloseStatus[code=1000, reason=null] in WebSocketClientSockJsSession[id='94ec7870e1e548b2bdb1a48780895e77, url=ws://localhost:8898/gs-guide-websocket]
20:27:12.271 [WebSocketClient-AsyncIO-2] DEBUG org.springframework.web.socket.adapter.NativeWebSocketSession - Closing StandardWebSocketSession[id=0, uri=null]
20:27:12.271 [WebSocketClient-AsyncIO-2] DEBUG org.springframework.web.socket.sockjs.client.WebSocketClientSockJsSession - Transport closed with CloseStatus[code=1000, reason=null] in WebSocketClientSockJsSession[id='94ec7870e1e548b2bdb1a48780895e77, url=ws://localhost:8898/gs-guide-websocket]
20:27:12.271 [WebSocketClient-AsyncIO-2] DEBUG org.springframework.messaging.simp.stomp.DefaultStompSession - Connection closed in session id=750c50a6-97cf-d7a3-d245-1a693cb7a6f3
20:27:12.271 [WebSocketClient-AsyncIO-2] ERROR org.springframework.web.socket.sockjs.client.WebSocketClientSockJsSession - Ignoring received message due to state CLOSED in WebSocketClientSockJsSession[id='94ec7870e1e548b2bdb1a48780895e77, url=ws://localhost:8898/gs-guide-websocket]
20:27:12.271 [WebSocketClient-AsyncIO-2] ERROR org.springframework.web.socket.sockjs.client.WebSocketClientSockJsSession - Ignoring received message due to state CLOSED in WebSocketClientSockJsSession[id='94ec7870e1e548b2bdb1a48780895e77, url=ws://localhost:8898/gs-guide-websocket]
20:27:12.271 [WebSocketClient-AsyncIO-2] ERROR org.springframework.web.socket.sockjs.client.WebSocketClientSockJsSession - Ignoring received message due to state CLOSED in WebSocketClientSockJsSession[id='94ec7870e1e548b2bdb1a48780895e77, url=ws://localhost:8898/gs-guide-websocket]
20:27:12.271 [WebSocketClient-AsyncIO-2] DEBUG org.springframework.web.socket.sockjs.client.WebSocketClientSockJsSession - Processing SockJS close frame with CloseStatus[code=1002, reason=null] in WebSocketClientSockJsSession[id='94ec7870e1e548b2bdb1a48780895e77, url=ws://localhost:8898/gs-guide-websocket]
20:27:12.271 [WebSocketClient-AsyncIO-2] DEBUG org.springframework.web.socket.sockjs.client.WebSocketClientSockJsSession - Ignoring close (already closing or closed): current state CLOSED

Process finished with exit code 0

页面显示收到的实际信息

将gs-messaging-stomp-websocket部署到服务器上，将connect连接地址换为服务器地址同样可以。

stompClient.connect("ws://localhost:{port}/gs-guide-websocket", headers, handler, port);

不同语言的WebSocket Client
http://stomp.github.io/implementations.html