Retry using the special http status code

Question

When accessing a specific website, sometimes I get an http response with a status code of 403. I wanted to re-execute the request in such cases (because in my specific situation this server throws 403 when it is really overloaded), I tried using ResponseHandler along with StandardHttpRequestRetryHandler but it didn’t work as I hoped; I expected throwing an exception in the ResponseHandler would trigger the StandardHttpRequestRetryHandler , but it doesn't seem to be that way. How can I achieve the desired functionality?

Here is an example code that illustrates my situation:

 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

Try using custom 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

You can do this by manually checking the status code, something like this:

 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); 

You need to add some things, for example, repeat the set number of times before throwing the final exception and catch some checked exceptions (for example, the InterruptedException created by Thread.sleep() ), but basically the code shows the main idea.