Java 10孵化器HttpClient请求Node.js本地服务器失败

最近在测试Java 9/10孵化器中的jdk.incubator.httpclient组件时，碰到了一个挺棘手的问题：用官方示例代码发送GET请求时，访问外部非本地URL完全正常，但请求本地服务器——不管是用localhost、127.0.0.1还是本机实际IP——都会直接失败，抛出EOFException，而且堆栈信息完全不涉及我自己写的业务代码。

测试代码 #

我用的是项目主页提供的基础示例代码：

URI uri = URI.create("http://192.168.1.102:8080/"); 
HttpRequest getRequest = HttpRequest.newBuilder() 
    .uri(uri) 
    .GET() 
    .build(); 
HttpResponse<String> response = client.send(getRequest, HttpResponse.BodyHandler.asString()); 
System.out.println("response to get: " + response.body()); 

报错信息 #

运行时会先弹出孵化器模块的警告，随后直接抛出异常：

WARNING: Using incubator modules: jdk.incubator.httpclient 
Exception in thread "main" java.io.EOFException: EOF reached while reading 
at jdk.incubator.httpclient/jdk.incubator.http.Http1AsyncReceiver$Http1TubeSubscriber.onComplete(Http1AsyncReceiver.java:507) 
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$InternalReadPublisher$ReadSubscription.signalCompletion(SocketTube.java:551) 
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$InternalReadPublisher$InternalReadSubscription.read(SocketTube.java:728) 
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$SocketFlowTask.run(SocketTube.java:171) 
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:198) 
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:271) 
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:224) 
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$InternalReadPublisher$InternalReadSubscription.signalReadable(SocketTube.java:675) 
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$InternalReadPublisher$ReadEvent.signalEvent(SocketTube.java:829) 
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$SocketFlowEvent.handle(SocketTube.java:243) 
at jdk.incubator.httpclient/jdk.incubator.http.HttpClientImpl$SelectorManager.handleEvent(HttpClientImpl.java:769) 
at jdk.incubator.httpclient/jdk.incubator.http.HttpClientImpl$SelectorManager.run(HttpClientImpl.java:731) 

排查与解决 #

一开始我怀疑是本地服务器没启动，但用浏览器可以正常访问，直接排除了这个可能。后来反复测试排查，发现问题根源和我当时用的Node.js/Express服务器的HTTP/2协议升级处理逻辑有关——这个孵化器版本的HttpClient在和这类服务器交互时，协议协商阶段可能出现了异常，导致连接提前断开，进而抛出EOF错误。

最后我更换了其他HTTP服务器进行测试，这个问题就完全消失了。

内容的提问来源于stack exchange，提问作者Toby Eggitt