Java HTTP Client输出空JSON

Question

I am running the following code:

CloseableHttpClient httpclient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet("http://10.0.0.22:8086/db/cadvisorDB/series?u=root&p=root&q=select%20max(memory_usage)%20from%20stats%20where%20container_name%20%3D%27execution_container_"+bench_list+"_"+i+"%27%20and%20memory_usage%20%3C%3E%200%20group%20by%20container_name");
//Thread.sleep(10000);
CloseableHttpResponse requestResponse = httpclient.execute(httpGet);
String response=EntityUtils.toString(requestResponse.getEntity());
System.out.println(response);

Output console:

[]

When I wait for the HttpResponse 30s it works. I got the complete response (JSON with data points) :

Thread.sleep(30000);

IS it possible using Apache Java client to tell the client to wait until getting a value different than "[]". I mean a non empty Json.

Using timeouts does not solve the problem.

Thank you in advance

Answer 1

Then setting the timeout will work.

HttpGet request = new HttpGet(url);

    // set timeouts as you like
    RequestConfig config = RequestConfig.custom()
            .setSocketTimeout(60 * 1000).setConnectTimeout(20 * 1000)
            .setConnectionRequestTimeout(20 * 1000).build();

    request.setConfig(config);

Answer 2

To be specific, no it is not possible simply using HttpClient "to tell the client to wait until getting a value different than" what it gets when the call is over. You have to program this yourself (in a loop or something.)

• Does it make a difference if the sleep() is before HttpClients.createDefault() ?
• Is it possible that your server at 10.0.0.22:8086 is just not ready when your code is executed? Is this server launched by the same app?

Answer 3

I had also same issue , but problem was 2 Http call making sequentially. so i have putted Thread.sleep(2000) for seconds and it worked.

Please confirm if your code making two rest call sequentially?

then may be you can place Thread.sleep just before second http call.