spring-boot支持websocket

spring-boot本身对websocket提供了很好的支持，可以直接原生支持sockjs和stomp协议。百度搜了一些中文文档，虽然也能实现websocket，但是并没有直接使用spring-boot直接支持的websocket的特性。

在实践中觉得stromp协议对于websocket开发的自由度影响比较大。这里给大家展示一种自由度比较大的方案。

主要就是三个组件，config，interceptor和handler

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@Configuration @EnableWebSocket public class MessageWebSocketConfig implements WebSocketConfigurer { @Override public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) { registry.addHandler(messageWebSocketHandler(), "/sockjs/message") .addInterceptors(new MessageWebSocketInterceptor()).withSockJS(); }   @Bean public MessageWebSocketHandler messageWebSocketHandler() { return new MessageWebSocketHandler(); } }

config需要继承WebSocketConfigurer需要重写registerWebSocketHandlers方法，指明handler和interceptor。

interceptor顾名思义为拦截器我们可以在websocket建立之间和之后做一些事情。重载beforeHandshake和afterHandshake就OK。我在beforeHandshake这里还操作了attributes。被修改的attributes会被带到后面websocket的session之中。

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public class MessageWebSocketInterceptor implements HandshakeInterceptor { @Override public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object> attributes) throws Exception { if (request instanceof ServletServerHttpRequest) { ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) request; String siteId = servletRequest.getServletRequest().getParameter("siteId"); String userId = servletRequest.getServletRequest().getParameter("userId"); if (siteId == null || userId == null) { return false; } attributes.put("siteId", siteId); attributes.put("userId", userId); } return true; }   @Override public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception exception) {   } }

handler里面就可以写websocket的逻辑啦

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public class MessageWebSocketHandler implements WebSocketHandler {   @Override public void afterConnectionEstablished(WebSocketSession session) {   }   @Override public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) {   }   @Override public void handleTransportError(WebSocketSession session, Throwable exception) { }   @Override public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) {   }   @Override public boolean supportsPartialMessages() { return false; } }

spring-boot单元测试可以写websocket-client

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@RunWith(SpringRunner.class) @SpringBootTest(classes = {Application.class}, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT) public class WebsocketTest { private final Logger logger = LoggerFactory.getLogger(WebsocketTest.class); private final WebSocketHttpHeaders headers = new WebSocketHttpHeaders(); final CountDownLatch latch = new CountDownLatch(1); final AtomicReference<Throwable> failure = new AtomicReference<>(); @LocalServerPort private int port; private SockJsClient sockJsClient;   @Before public void setup() { List<Transport> transports = new ArrayList<>(); transports.add(new WebSocketTransport(new StandardWebSocketClient())); transports.add(new RestTemplateXhrTransport()); this.sockJsClient = new SockJsClient(transports); }   @Test public void getGreeting() throws Exception {   this.sockJsClient.doHandshake(new TestWebSocketHandler(failure), "ws://localhost:"+String.valueOf(port)+"/sockjs/message?siteId=webtrn&userId=lucy"); if (latch.await(60, TimeUnit.SECONDS)) { if (failure.get() != null) { throw new AssertionError("", failure.get()); } } else { fail("Greeting not received"); }   }       private class TestWebSocketHandler implements WebSocketHandler {   private final AtomicReference<Throwable> failure;   TestWebSocketHandler() { this.failure = null; }   ;   TestWebSocketHandler(AtomicReference<Throwable> failure) { this.failure = failure; }   ;   @Override public void afterConnectionEstablished(WebSocketSession session) throws Exception { logger.info("client connection established"); session.sendMessage(new TextMessage("hello websocket server!")); }   @Override public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception { String payload = (String) message.getPayload(); logger.info("client handle message: " + payload); if (payload.equals("hello websocket client! webtrn lucy")) { latch.countDown(); }   if (payload.equals("web socket notify")) { latch.countDown(); } }   @Override public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception { logger.info("client transport error"); }   @Override public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception { logger.info("client connection closed"); }   @Override public boolean supportsPartialMessages() { return false; } }   }

如果采用stomp协议的话可以参考spring-boot的一个ws-guide。有问题还是直接看spring文档比较好。