如果Java中的响应时间长于n秒，则重新运行http post请求？

Question

我正在使用 Java 调用 REST API，但有时响应有时会出现延迟。所以我想以某种方式检查响应是否花费太长时间（例如 2 或 3 秒）并重新启动/重新运行 http post 请求，因为我不需要“卡住”等待响应的请求，这可能来很多，很晚。

到目前为止，这是我的一段代码：

private final CloseableHttpClient client;
HttpResponse response;
List<NameValuePair> parameters;
HttpPost post;

public String getRoleData(int roleid) {
    this.post = new HttpPost(this.createUrl("role/eventdata"));
    this.post.setHeader("apikey", this.apikey);
    this.parameters = new ArrayList<>();
    this.parameters.add(new BasicNameValuePair("roleid", String.valueOf(roleid)));
    try {
        post.setEntity(new UrlEncodedFormEntity(this.parameters));
        this.response = client.execute(post);
        String JsonResponse = EntityUtils.toString(this.response.getEntity(), StandardCharsets.UTF_8);
        return JsonResponse;
    } catch (UnsupportedEncodingException ex) {
        System.out.println("API Unsupported instruction entry");
    } catch (IOException ex) {
        System.out.println("API IO issue");
    }
    return "Empty response";
}

Answer 1

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.httpclient.NameValuePair;
import org.apache.http.HttpResponse;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.util.EntityUtils;

public class Test {

    public static void main(String[] args) {
        int timeoutInMillis = 10;
        RequestConfig config = RequestConfig.custom().
              setConnectTimeout(timeoutInMillis).
              setConnectionRequestTimeout(timeoutInMillis).
              setSocketTimeout(timeoutInMillis).build();
        final CloseableHttpClient client = HttpClientBuilder.create()
                  .setDefaultRequestConfig(config).build();
        HttpPost post = new HttpPost("https://reqres.in/api/api/users");
        //this.post.setHeader("apikey", this.apikey);
        List<NameValuePair> parameters = new ArrayList<NameValuePair>();
        parameters.add(new NameValuePair("name", "test1"));
        parameters.add(new NameValuePair("job", "job1"));
        try {
            //post.setEntity(new UrlEncodedFormEntity(this.parameters));
            HttpResponse response = client.execute(post);
            String jsonResponse = EntityUtils.toString(response.getEntity(), StandardCharsets.UTF_8);
            System.out.println(jsonResponse);
        } catch (UnsupportedEncodingException ex) {
            System.out.println("API Unsupported instruction entry");
        } catch (IOException ex) {
            System.out.println("IO issue" + ex.getCause().getClass());
        }
    }
}

应该和上面有点类似。检查 RequestConfig 部分和异常处理部分。您可以在错误处理中添加标志并重试。我们在这里为 http 客户端设置超时值。您可以通过一些 java doc 了解更多详细信息。

顺便说一句，您使用的 POST 方法根据定义不是幂等的。因此，再次重新运行相同的请求时需要小心。超时后服务器可能已经处理完毕。