从 java WebSocketStompClient 发送 BinaryMessage答案

【问题标题】：Sending a BinaryMessage from java WebSocketStompClient从 java WebSocketStompClient 发送 BinaryMessage
【发布时间】：2015-05-27 17:40:42
【问题描述】：

根据 (Is it possible to send binary data with STOMP over WebSockets using Spring-WebSockets?) 看来，应该可以通过 websocket 使用 STOMP 发送二进制消息。

我已将 WebSocketStompClient 配置如下：

List<Transport> transports = new ArrayList<>(1);
transports.add(new WebSocketTransport( new StandardWebSocketClient()) );
WebSocketClient transport = new SockJsClient(transports);
WebSocketStompClient stompClient = new WebSocketStompClient(transport);
// using a custom converter to serialize java object to byte[]
stompClient.setMessageConverter( new SerializedJavaObjectMessageConverter() );

我正在使用以下方式发送消息：

StompHeaders stompHeaders = new StompHeaders();
stompHeaders.setDestination( "/app/greetings");
stompHeaders.setContentType( MimeTypeUtils.APPLICATION_OCTET_STREAM );
session.send(stompHeaders, new Greeting( message ));

我收到以下断言的异常：

Assert.isInstanceOf(TextMessage.class, message, this + " supports text messages only.");

在 org.springframework.web.socket.sockjs.client.AbstractClientSockJs（下）中找到，它似乎只支持 TextMessage：

@Override
public final void sendMessage(WebSocketMessage<?> message) throws IOException {
    Assert.state(State.OPEN.equals(this.state), this + " is not open, current state=" + this.state);
    Assert.isInstanceOf(TextMessage.class, message, this + " supports text messages only.");
    String payload = ((TextMessage) message).getPayload();
    payload = getMessageCodec().encode(new String[] { payload });
    payload = payload.substring(1); // the client-side doesn't need message framing (letter "a")
    message = new TextMessage(payload);
    if (logger.isTraceEnabled()) {
            logger.trace("Sending message " + message + " in " + this);
    }
    sendInternal((TextMessage) message);
}

如上配置的新 java 客户端 WebSocketStompClient (4.2-SNAPSHOT) 是否支持发送二进制消息？

更新：

以下客户端配置有效：

WebSocketClient transport = new StandardWebSocketClient();
WebSocketStompClient stompClient = new WebSocketStompClient(transport)

【问题讨论】：

你能澄清你的问题吗？
@QPaysTaxes - 根据您的评论，我已经改写了这个问题。
根据 Rossen Stoyanchev 在jira.spring.io/browse/SPR-12301 上的评论，SockJs 不支持二进制消息 (github.com/sockjs/sockjs-protocol/…)

标签： java spring spring-websocket

【解决方案1】：

我可以通过发送 TextMessage 来实现此功能。我创建了另一个自定义 MessageConverter，Base64 对序列化对象进行编码/解码：

public class Base64JavaObjectMessageConverter extends AbstractMessageConverter {

    public Base64JavaObjectMessageConverter() {
        super(MimeTypeUtils.TEXT_PLAIN);
    }

    @Override
    protected boolean supports(Class<?> clazz) {
        return true;
    }

    @Override
    public Object convertFromInternal(Message<?> message, Class<?> targetClass) {
        byte[] messageBytes = Base64.getDecoder().decode( (byte[])message.getPayload() );
        return SerializationUtils.deserialize( messageBytes  );
    }

    @Override
    public Object convertToInternal(Object payload, MessageHeaders headers) {
        byte[] messageBytes = SerializationUtils.serialize( payload );
        return Base64.getEncoder().encode( messageBytes);
    }

}

【讨论】：