使用google-http-client和google-http-client-apache-v2在代理后面生成NonRepeatableRequestException。

Question

我使用google-http-client和google-http-client-apache-v2库在代理后面创建POST request 。

// 1.- Setting ssl and proxy
HttpClientBuilder builder = HttpClientBuilder.create();
            
SSLContext sslContext = SslUtils.getTlsSslContext();
SslUtils.initSslContext(sslContext, GoogleUtils.getCertificateTrustStore(), SslUtils.getPkixTrustManagerFactory());
builder.setSSLSocketFactory(new SSLConnectionSocketFactory(sslContext));
            
builder.setProxy(new HttpHost(host, port));
CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
credentialsProvider.setCredentials(new AuthScope(host, port), new UsernamePasswordCredentials(user, pass));
builder.setDefaultCredentialsProvider(credentialsProvider);

// 2.- Build request
HttpTransport httpTransport = new ApacheHttpTransport(builder.build());
HttpRequestFactory factory = httpTransport.createRequestFactory(credential);

HttpContent httpContent = new ByteArrayContent("application/json", "{}")
HttpRequest request = factory.buildRequest("POST", new GenericUrl(url), httpContent);

// 3.- Execute request
HttpResponse httpResponse = request.execute();

该请求产生一个NonRepeatableRequestException

org.apache.http.client.ClientProtocolException
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:187) ~[httpclient-4.5.13.jar!/:4.5.13]
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83) ~[httpclient-4.5.13.jar!/:4.5.13]
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:108) ~[httpclient-4.5.13.jar!/:4.5.13]
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56) ~[httpclient-4.5.13.jar!/:4.5.13]
    at com.google.api.client.http.apache.v2.ApacheHttpRequest.execute(ApacheHttpRequest.java:73) ~[google-http-client-apache-v2-1.39.2.jar!/:?]
    at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:1012) ~[google-http-client-1.39.2.jar!/:1.39.2]
    at 
    ...
Caused by: org.apache.http.client.NonRepeatableRequestException: Cannot retry request with a non-repeatable request entity.
    at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:225) ~[httpclient-4.5.13.jar!/:4.5.13]
    at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:186) ~[httpclient-4.5.13.jar!/:4.5.13]
    at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89) ~[httpclient-4.5.13.jar!/:4.5.13]
    at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110) ~[httpclient-4.5.13.jar!/:4.5.13]
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185) ~[httpclient-4.5.13.jar!/:4.5.13]
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83) ~[httpclient-4.5.13.jar!/:4.5.13]
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:108) ~[httpclient-4.5.13.jar!/:4.5.13]
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56) ~[httpclient-4.5.13.jar!/:4.5.13]
    at com.google.api.client.http.apache.v2.ApacheHttpRequest.execute(ApacheHttpRequest.java:73) ~[google-http-client-apache-v2-1.39.2.jar!/:?]
    at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:1012) ~[google-http-client-1.39.2.jar!/:1.39.2]

似乎ApacheHttpRequest将ByteArrayContent封装为可重复的(参见JavaDoc)在ContentEntity (即non-repeatable. )中。

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在google库中调试执行时，代理返回"407代理身份验证所需“，然后尝试重复请求(猜测包括凭据)，而出现此异常是因为google库使用的ContentEntity是不可重复的。

是否有任何方法可以避免与代理握手，包括在第一个请求中包含凭据，以避免实体的重用？

有没有办法告诉使用可重复实体的google库？

尝试使用折叠库版本：

• google-api-client-1.31.5
• google-http-client-jackson2-1.39.2
• google-oauth-client-1.31.5
• google-http-client-apache-v2-1.39.2
• google-http-client-1.39.2
• httpclient-4.5.13
• httpcore-4.4.14

Answer 1

我在github上发布了解决办法，以防它对某人有帮助：

作为解决办法，我尝试的是将ApacheHttpTransport包装在CustomApacheHttpTransport，中，它将方法的结果委托给ApacheHttpTransport，但buildRequest方法除外。

CustomApacheHttpTransport中的这个buildRequest方法生成一个类型为CustomApacheHttpRequest.的自定义请求。

public final class CustomApacheHttpTransport extends HttpTransport {
    
    private ApacheHttpTransport apacheHttpTransport;
    
    public CustomApacheHttpTransport (HttpClient httpClient) {
        this.apacheHttpTransport = new ApacheHttpTransport(httpClient);
    }
    
    @Override
    protected LowLevelHttpRequest buildRequest (String method, String url) {
        HttpRequestBase requestBase;
        if (method.equals("DELETE")) {
            requestBase = new HttpDelete(url);
        } else if (method.equals("GET")) {
            requestBase = new HttpGet(url);
        } else if (method.equals("HEAD")) {
            requestBase = new HttpHead(url);
        } else if (method.equals("PATCH")) {
            requestBase = new HttpPatch(url);
        } else if (method.equals("POST")) {
            ..
        }
        return new CustomApacheHttpRequest(apacheHttpTransport.getHttpClient(), requestBase);
    }
}

这个自定义请求与ApacheHttpRequest类似，除非它在执行时创建一个自定义实体，CustomContentEntity，将根据请求内容是否支持重试而可重复。

final class CustomApacheHttpRequest extends LowLevelHttpRequest {
    
    private final HttpClient httpClient;
    private final HttpRequestBase request;
    private RequestConfig.Builder requestConfig;
    
    CustomApacheHttpRequest (HttpClient httpClient, HttpRequestBase request) {
        this.httpClient = httpClient;
        this.request = request;
        this.requestConfig = RequestConfig.custom().setRedirectsEnabled(false).setNormalizeUri(false).setStaleConnectionCheckEnabled(false);
    }
    
    ...
        
    @Override
    public LowLevelHttpResponse execute () throws IOException {
        if (this.getStreamingContent() != null) {
            Preconditions.checkState(request instanceof HttpEntityEnclosingRequest, "Apache HTTP client does not support %s requests with content.", request.getRequestLine().getMethod());
            
            CustomContentEntity entity = new CustomContentEntity(this.getContentLength(), this.getStreamingContent());
            entity.setContentEncoding(this.getContentEncoding());
            entity.setContentType(this.getContentType());
            if (this.getContentLength() == -1L) {
                entity.setChunked(true);
            }
            ((HttpEntityEnclosingRequest) request).setEntity(entity);
        }
        
        request.setConfig(requestConfig.build());
        return new CustomApacheHttpResponse(request, httpClient.execute(request));
    }
}

CustomContentEntity中的关键是isRepeatable方法，它不像ContentEntity那样总是返回false。

final class CustomContentEntity extends AbstractHttpEntity {
    
    private final long contentLength;
    private final StreamingContent streamingContent;
    
    CustomContentEntity (long contentLength, StreamingContent streamingContent) {
        this.contentLength = contentLength;
        this.streamingContent = streamingContent;
    }
    
    @Override
    public boolean isRepeatable () {
        return ((HttpContent) streamingContent).retrySupported();
    }
    ...
}

此外，我还必须创建CustomApacheHttpResponse作为CustomApacheHttpRequest的响应，因为ApacheHttpResponse是包私有的(CustomApacheHttpResponse与ApacheHttpResponse).完全一样。