Question

我正在使用tomcat 8.0.15，spring 4.1.5。

我实现了3个强制函数，用于使用websocket，如下所示。这很简单。

private Map<String, WebSocketSession> map_users = new ConcurrentHashMap<>();
private Map<String, String> map_id = new ConcurrentHashMap<>();

public void afterConnectionEstablished(WebSocketSession wss) throws Exception {
    map_users.put(wss.getId(), wss);
}

public void afterConnectionClosed(WebSocketSession wss, CloseStatus cs) throws Exception {
    map_users.remove(wss.getId());

    // remove user
    String username = map_id.get(wss.getId());
    if (username != null) {
        map_id.remove(wss.getId());
        map_id.remove(username);
    }
}

public void handleTextMessage(WebSocketSession wss, TextMessage tm) throws Exception {
    String str = tm.getPayload();
    String username = ...;

    // regist user
    if (!map_id.get(wss.getId())) {
        map_id.put(wss.getId(), username);
        map_id.put(username, wss.getId());
    }

    for (WebSocketSession w: map_users.values()) {
        w.sendMessage(new TextMessage(wss.getId() + " send to " + w.getId() + ", msg:" + tm.getPayload()));
    }
}

某些客户端发送消息，其他客户端通过handleTextMessage获取消息。

在我的情况下，如果没有handleTextMessage函数，服务器程序想要向客户端发送文本消息。（为此我将WebSocketSession的ID和用户名保存到map_id中）

String websocketsesssion_id = map_id.get(username);
WebSocketSession wss = map_users.get(websocketsesssion_id);
wss.sendMessage(new TextMessage(new java.util.Date()));

以上代码效果很好。但是当一些客户端的WebSocketSession正在使用并尝试同时使用时，它会产生错误。它的意思是 1.一些客户端发送消息 - ＆gt; handleTextMessage被调用 - ＆gt;客户端的WebSocketSession正在使用 2.服务器程序想要向该客户端发送消息 - ＆gt;从地图获取客户端的WebSocketSession - ＆gt;尝试使用相同的WebSocketSession发送消息

Stacktrace:] with root cause
java.lang.IllegalStateException: The remote endpoint was in state [TEXT_PARTIAL_WRITING] which is an invalid state for called method
    at org.apache.tomcat.websocket.WsRemoteEndpointImplBase$StateMachine.checkState(WsRemoteEndpointImplBase.java:1092)
    at org.apache.tomcat.websocket.WsRemoteEndpointImplBase$StateMachine.textPartialStart(WsRemoteEndpointImplBase.java:1050)
    at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendPartialString(WsRemoteEndpointImplBase.java:218)
    at org.apache.tomcat.websocket.WsRemoteEndpointBasic.sendText(WsRemoteEndpointBasic.java:49)
    at org.springframework.web.socket.adapter.standard.StandardWebSocketSession.sendTextMessage(StandardWebSocketSession.java:197)
    at org.springframework.web.socket.adapter.AbstractWebSocketSession.sendMessage(AbstractWebSocketSession.java:105)
    at org.springframework.web.socket.sockjs.transport.session.WebSocketServerSockJsSession.writeFrameInternal(WebSocketServerSockJsSession.java:222)
    at org.springframework.web.socket.sockjs.transport.session.AbstractSockJsSession.writeFrame(AbstractSockJsSession.java:325)
    at org.springframework.web.socket.sockjs.transport.session.WebSocketServerSockJsSession.sendMessageInternal(WebSocketServerSockJsSession.java:212)
    at org.springframework.web.socket.sockjs.transport.session.AbstractSockJsSession.sendMessage(AbstractSockJsSession.java:161)

结果，WebSocketSession关闭，客户端必须再次打开新的WebSocketSession。

所以，我的问题是：

我可以检查WebSocketSession是否正在使用中吗？（在handleTextMessage函数之外）

Answer 1

问题是几个线程尝试在套接字上同时写入：

尝试：

String websocketsesssion_id = map_id.get(username);
WebSocketSession wss = map_users.get(websocketsesssion_id);
synchronized(wss) {
 wss.sendMessage(new TextMessage(new java.util.Date()));
}

Answer 2

虽然同步sendMessage()调用有助于ws：//连接，但它对wss://, i.e. SSL/TLS connection无效。如果您在阅读部分消息时尝试发送部分消息，则100％失败。我在Spring Boot 1.4.2 RELEASE（tomcat 8.5.6）

上测试了它

与tomcat 8.5.9相同。请参阅下面的跟踪堆栈。

[pool-18-thread-1] [GenericMessageEndpoint] Sending message to the endpoint: 
[pool-18-thread-2] [GenericMessageEndpoint] Sending message to the endpoint: 
[pool-18-thread-3] [GenericMessageEndpoint] Sending message to the endpoint: 

[https-jsse-nio-8443-exec-1] [FrontendWebSocketHandler] Message from 0, isLast: false, length: 16384
[https-jsse-nio-8443-exec-1] [FrontendWebSocketHandler] Message from 0, isLast: false, length: 16384

[pool-18-thread-3] [FrontendWebSocketHandler] Transport error. Session: StandardWebSocketSession[id=0, uri=/myt/websocket]
java.io.IOException: java.io.IOException: Unable to wrap data, invalid status [CLOSED]
    at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendMessageBlock(WsRemoteEndpointImplBase.java:315)
    at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendMessageBlock(WsRemoteEndpointImplBase.java:258)
    at org.apache.tomcat.websocket.WsSession.sendCloseMessage(WsSession.java:606)
    at org.apache.tomcat.websocket.WsSession.doClose(WsSession.java:494)
    at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendMessageBlock(WsRemoteEndpointImplBase.java:313)
    at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendMessageBlock(WsRemoteEndpointImplBase.java:250)
    at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendPartialString(WsRemoteEndpointImplBase.java:223)
    at org.apache.tomcat.websocket.WsRemoteEndpointBasic.sendText(WsRemoteEndpointBasic.java:49)
    at org.springframework.web.socket.adapter.standard.StandardWebSocketSession.sendTextMessage(StandardWebSocketSession.java:197)
    at org.springframework.web.socket.adapter.AbstractWebSocketSession.sendMessage(AbstractWebSocketSession.java:104)
    at com.ebs.mytreasury.frontend.websocket.FrontendWebSocketHandler.send(FrontendWebSocketHandler.java:180)
    at com.ebs.mytreasury.frontend.websocket.FrontendWebSocketHandler.send(FrontendWebSocketHandler.java:24)
    at com.ebs.mytreasury.frontend.GenericMessageEndpoint.sendMessage(GenericMessageEndpoint.java:72)
    at com.ebs.mytreasury.frontend.GenericMessageEndpoint.send(GenericMessageEndpoint.java:57)
    at com.mytreasury.services.backend.MessageSender.process(MessageSender.java:24)
    at com.mytreasury.services.backend.AbstractTopicMessageHandler.handle(AbstractTopicMessageHandler.java:47)
    at com.mytreasury.services.backend.AbstractTopicMessageHandler.handle(AbstractTopicMessageHandler.java:52)
    at com.mytreasury.services.backend.AbstractTopicMessageHandler.handle(AbstractTopicMessageHandler.java:52)
    at com.mytreasury.services.backend.AbstractTopicMessageHandler.handle(AbstractTopicMessageHandler.java:52)
    at com.mytreasury.services.backend.AbstractTopicMessageHandler.handle(AbstractTopicMessageHandler.java:52)
    at com.mytreasury.services.backend.AbstractTopicMessageHandler.handle(AbstractTopicMessageHandler.java:52)
    at com.mytreasury.services.backend.AbstractTopicMessageHandler.handle(AbstractTopicMessageHandler.java:52)
    at com.mytreasury.services.backend.AbstractTopicMessageHandler.handle(AbstractTopicMessageHandler.java:52)
    at com.mytreasury.services.backend.AbstractTopicMessageHandler.handle(AbstractTopicMessageHandler.java:52)
    at com.ebs.mytreasury.frontend.message.handler.ResponseGenericMessageHandler.handle(ResponseGenericMessageHandler.java:52)
    at com.ebs.mytreasury.frontend.socket.EventPublisherSocketHandler.handle(EventPublisherSocketHandler.java:96)
    at com.ebs.mytreasury.frontend.socket.EventPublisherSocketHandler$1$1.run(EventPublisherSocketHandler.java:135)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.IOException: Unable to wrap data, invalid status [CLOSED]
    at org.apache.tomcat.util.net.SecureNioChannel.write(SecureNioChannel.java:647)
    at org.apache.tomcat.util.net.NioBlockingSelector.write(NioBlockingSelector.java:101)
    at org.apache.tomcat.util.net.NioSelectorPool.write(NioSelectorPool.java:157)
    at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.doWrite(NioEndpoint.java:1241)
    at org.apache.tomcat.util.net.SocketWrapperBase.doWrite(SocketWrapperBase.java:670)
    at org.apache.tomcat.util.net.SocketWrapperBase.flushBlocking(SocketWrapperBase.java:607)
    at org.apache.tomcat.util.net.SocketWrapperBase.flush(SocketWrapperBase.java:597)
    at org.apache.tomcat.websocket.server.WsRemoteEndpointImplServer.doWrite(WsRemoteEndpointImplServer.java:95)
    at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.writeMessagePart(WsRemoteEndpointImplBase.java:494)
    at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendMessageBlock(WsRemoteEndpointImplBase.java:309)
    ... 29 common frames omitted
[https-jsse-nio-8443-exec-3] [FrontendWebSocketHandler] Transport error. Session: StandardWebSocketSession[id=0, uri=/myt/websocket]
javax.net.ssl.SSLException: bad record MAC
    at sun.security.ssl.Alerts.getSSLException(Alerts.java:208)
    at sun.security.ssl.SSLEngineImpl.fatal(SSLEngineImpl.java:1728)
    at sun.security.ssl.SSLEngineImpl.readRecord(SSLEngineImpl.java:981)
    at sun.security.ssl.SSLEngineImpl.readNetRecord(SSLEngineImpl.java:907)
    at sun.security.ssl.SSLEngineImpl.unwrap(SSLEngineImpl.java:781)
    at javax.net.ssl.SSLEngine.unwrap(SSLEngine.java:624)
    at org.apache.tomcat.util.net.SecureNioChannel.read(SecureNioChannel.java:563)
    at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.fillReadBuffer(NioEndpoint.java:1222)
    at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.fillReadBuffer(NioEndpoint.java:1195)
    at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.read(NioEndpoint.java:1168)
    at org.apache.tomcat.websocket.server.WsFrameServer.onDataAvailable(WsFrameServer.java:62)
    at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.upgradeDispatch(WsHttpUpgradeHandler.java:148)
    at org.apache.coyote.http11.upgrade.UpgradeProcessorInternal.dispatch(UpgradeProcessorInternal.java:54)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:53)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:789)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1437)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
Caused by: javax.crypto.BadPaddingException: bad record MAC
    at sun.security.ssl.EngineInputRecord.decrypt(EngineInputRecord.java:238)
    at sun.security.ssl.SSLEngineImpl.readRecord(SSLEngineImpl.java:974)
    ... 18 common frames omitted
[pool-18-thread-3] [FrontendWebSocketHandler] Connection closed. Session: StandardWebSocketSession[id=0, uri=/myt/websocket], CloseStatus: CloseStatus[code=1006, reason=Unable to wrap data, invalid status [CLOSED]];
[pool-18-thread-2] [GenericMessageEndpoint] Exception while sending message to the endpoint: java.lang.IllegalStateException: The remote endpoint was in state [TEXT_PARTIAL_WRITING] which is an invalid state for called method,
[pool-18-thread-1] [GenericMessageEndpoint] Exception while sending message to the endpoint: java.lang.IllegalStateException: The remote endpoint was in state [TEXT_PARTIAL_WRITING] which is an invalid state for called method, 
[pool-18-thread-3] [GenericMessageEndpoint] Exception while sending message to the endpoint: java.io.IOException: java.io.IOException: Unable to wrap data, invalid status [CLOSED],

Answer 3

Websocket会话可能已经由另一个线程处于 State.TEXT_PARTIAL_WRITING ，而不是 TEXT_PARTIAL_READY ，如此处的代码所示

https://www.codota.com/web/assistant/code/rs/5c666c3d1095a50001c2b6f4#L1182

WebSocket远程端点处于[TEXT_PARTIAL_WRITING]状态

3 个答案: