强制重试特定的HTTP状态代码

Question

在处理特定网站时，有时会收到状态码为403的http响应。在这种情况下，我想重新执行该请求（因为在我的特定情况下，该服务器实际上超载时会抛出403）。我曾尝试将a
ResponseHandler和a
一起使用StandardHttpRequestRetryHandler，但是它没有按我希望的方式工作；我希望在中ResponseHandler引发异常会触发StandardHttpRequestRetryHandler，但事实并非如此。如何获得所需的功能？

这是说明我的情况的示例代码：

import java.io.IOException;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.client.methods.RequestBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.client.StandardHttpRequestRetryHandler;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.EntityUtils;


public class Main {

  public static void main(String[] args) throws Exception {

    // a response handler that throws an exception if status is not 200
    ResponseHandler<String> responseHandler = new ResponseHandler<String> () {

      @Override
      public String handleResponse(HttpResponse response) throws
        ClientProtocolException, IOException
      {
        System.out.println("-> Handling response");

        if (response.getStatusLine().getStatusCode() != 200){
          // I expected this to trigger the retryHandler 
          throw new ClientProtocolException("Status code not supported");
        }
        return EntityUtils.toString(response.getEntity());
      }

    };

    StandardHttpRequestRetryHandler retryHandler = 
        new StandardHttpRequestRetryHandler(5, true)
    {
      @Override
      public boolean retryRequest(
          final IOException exception,
          final int executionCount,
          final HttpContext context)
      {
        System.out.println("-> Retrying request");
        return super.retryRequest(exception, executionCount, context);
      }
    };

    // my client with my retry handler
    HttpClient client = HttpClients
        .custom()
        .setRetryHandler(retryHandler)
        .build();

    // my request
    HttpUriRequest request = RequestBuilder
        .create("GET")
        .setUri("http://httpstat.us/403")         //always returns 403
        .build();

    String contents = client.execute(request, responseHandler);

    System.out.println(contents);
  }


}

Answer 1

尝试使用自定义 ServiceUnavailableRetryStrategy

CloseableHttpClient client = HttpClients.custom()
        .setServiceUnavailableRetryStrategy(new ServiceUnavailableRetryStrategy() {
            @Override
            public boolean retryRequest(
                    final HttpResponse response, final int executionCount, final HttpContext context) {
                int statusCode = response.getStatusLine().getStatusCode();
                return statusCode == 403 && executionCount < 5;
            }

            @Override
            public long getRetryInterval() {
                return 0;
            }
        })
        .build();