如何在Google HTTP Client中增加ReadTimeout

Question

我的应用程序在GAE中运行。此应用程序对我的CloudML进行REST调用。

这是该代码

GoogleCredential credential = GoogleCredential.getApplicationDefault()
        .createScoped(Collections.singleton(CLOUDML_SCOPE));
HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
HttpRequestFactory requestFactory = httpTransport.createRequestFactory(
        credential);
GenericUrl url = new GenericUrl(cloudMLRestUrl);

JacksonFactory jacksonFactory = new JacksonFactory();
JsonHttpContent jsonHttpContent = new JsonHttpContent(jacksonFactory, getPayLoad());

ByteArrayOutputStream baos = new ByteArrayOutputStream();

jsonHttpContent.setWrapperKey("instances");
jsonHttpContent.writeTo(baos);
LOG.info("Executing request... " + baos.toString());
HttpRequest request = requestFactory.buildPostRequest(url, jsonHttpContent);

HttpResponse response = request.execute();  

上面的代码通常会导致ReadTimeout异常。

java.net.SocketTimeoutException: Read timed out at 
java.net.SocketInputStream.socketRead0(Native Method) ~[na:1.8.0_121] at 
java.net.SocketInputStream.socketRead(SocketInputStream.java:116) 
~[na:1.8.0_121] at 
java.net.SocketInputStream.read(SocketInputStream.java:171) ~[na:1.8.0_121] 
at 

似乎我们可以添加具有自定义超时的HttpRequestInitializer，但是在创建HttpRequestFactory时我们需要传递GoogleCredential HttpRequestFactory requestFactory = httpTransport.createRequestFactory(GoogleCredential);

因此，我不能使用自定义HTTPRequestInitializer。如何增加使用GoogleCredential HTTPRequestInitializer创建的HttpRequestFactory的readTimeout？

Answer 1

我没有尝试过，但是希望您能够有效地将请求初始化程序链接在一起：

final GoogleCredential credential = ...;
HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
HttpRequestFactory requestFactory = httpTransport.createRequestFactory(
    new HttpRequestInitializer() {
        @Override public void initialize(HttpRequest request) {
            credential.initialize(request);
            request.setReadTimeout(...);
        }
    });

或作为lambda表达式：

final GoogleCredential credential = ...;
HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
HttpRequestFactory requestFactory = httpTransport.createRequestFactory(
    request -> {
        credential.initialize(request);
        request.setReadTimeout(...);
    });

换句话说，当创建新请求时，凭据可以设置标头等，然后您还可以设置读取超时。