Question

处理特定网站时，有时我会收到状态码为403的http响应。我想在这种情况下重新执行请求（因为，在我的特定情况下，此服务器在实际超载时会抛出403）。我试图将ResponseHandler与StandardHttpRequestRetryHandler一起使用，但它并没有像我希望的那样工作;我期望在ResponseHandler中抛出异常会触发StandardHttpRequestRetryHandler，但似乎并非如此。如何实现所需的功能？

以下示例代码说明了我的情况：

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();

Answer 2

您可以通过手动检查状态代码来执行此操作，如下所示：

CloseableHttpResponse response = null;
boolean success = false;
while(!success) {
    response = client.execute(httpGet);
    int status = response.getStatusLine().getStatusCode();
    success = (status == 200);
    if (!success) {
        if(status == 403) {
            Thread.sleep(2000); // wait 2 seconds before retrying
        } else {
            throw new RuntimeException("Something went wrong: HTTP status: " + status);
        }
    }
}
String contents = EntityUtils.toString(response.getEntity());
response.close();

// ....

System.out.println(contents);

您需要添加一些内容，例如在抛出最终异常并捕获一些已检查的异常（例如Thread.sleep()抛出的InterruptedException）之前重试预定义次数，但基本上代码显示主要想法。 / p>

强制重试特定的http状态代码

2 个答案: