Spring WebClient发生连接断开时如何处理异常

Question

我正在使用Spring WebClient接收服务器已发送事件。当服务器关闭时，出现以下异常堆栈：

[reactor.ipc.netty.channel.ChannelOperations:283] - [HttpClient] Error processing connection. Requesting close the channel
java.io.IOException: An existing connection was forcibly closed by the remote host

[reactor-http-nio-4] [] [] [reactor.ipc.netty.channel.ContextHandler:283] - Error cannot be forwarded to user-facing Mono
java.io.IOException: An existing connection was forcibly closed by the remote host

[io.netty.channel.AbstractChannelHandlerContext:146] - An exception '{}' [enable DEBUG level for full stacktrace] was thrown by a user handler's exceptionCaught() method while handling the following exception:
java.io.IOException: An existing connection was forcibly closed by the remote host

在WebClient的深处很明显，Netty捕获了异常。但是，我的问题是：如何捕获它，以便可以优雅地处理它。

我的代码：

final Flux<Object> stream = WebClient.builder()
            .baseUrl("http://localhost:8080/ssp/common/v1/eventstream")
            .build()
            .get()
            .retrieve()
            .bodyToFlux(ServerSentEvent.class)
            .flatMap(e -> Mono.justOrEmpty(e.data()))
            .repeat();

    stream.doOnError(e -> System.out.println(e));
    stream.subscribe(e -> processEvent(e));

stream.doOnError（）在这种情况下无济于事。在M. Deinum的评论下，我修改了代码：

final Flux<Object> stream = WebClient.builder()
            .baseUrl("http://localhost:8080/ssp/common/v1/eventstream")
            .build()
            .get()
            .retrieve()
            .bodyToFlux(ServerSentEvent.class)
            .flatMap(e -> Mono.justOrEmpty(e.data()))
            .doOnError(e -> System.out.println("haha"))
            .repeat();

    stream.subscribe(e -> processEvent(e));

然后，它会变得更好一点。我打印了“哈哈”字样，但仍然有异常堆栈（短了一点）：

[reactor.ipc.netty.channel.ChannelOperations:283] - [HttpClient] Error processing connection. Requesting close the channel
java.io.IOException: An existing connection was forcibly closed by the remote host

[reactor-http-nio-4] [] [] [reactor.ipc.netty.channel.ContextHandler:283] - Error cannot be forwarded to user-facing Mono
java.io.IOException: An existing connection was forcibly closed by the remote host