spring RestTemplate 出現 NoHttpResponseException 和 ConnectionTimeoutException

使用 httpclient.4.5.6

springboot 2.0.8RELEASE 

 

RetryExec.java

CloseableHttpResponse execute()

try {

    return this.requestExecutor.execute(route, request, context, execAware);

} catch(final IOException ex) {

     if (retryHandler.retryRequest(ex.execCount,  context) {

 

     } else {

          if (ex instanceof NoHttpResponseException) {

         }

     }

}

 

@Configuration
public class RestTemplateConfig {

    // builder.build();的並發量是5，不如 new RestTemplate() 默認200
    @Bean
    public RestTemplate restTemplate(RestTemplateBuilder builder) {
        return builder.build();
    }
}

這樣建的RestTemplate 沒有重發 NoHttpResponseException和org.apache.http.conn.ConnectTimeoutException 需要自定義 RetryHandler 

NoHttpResponseException 服務端斷開連接，客戶端使用了斷開的連接發送，導致報錯，默認的RestTemplate 會有connection有效性檢查，默認2秒檢查一次

要設置客戶端的Keep-Alive，客戶端應該設置的比服務端短，默認RestTemplate不會設置

 

帶Keep-Alive的頭部 示例

HTTP/1.1 200 OK
Connection: Keep-Alive
Content-Encoding: gzip
Content-Type: text/html; charset=utf-8
Date: Thu, 11 Aug 2016 15:23:13 GMT
Keep-Alive: timeout=5, max=1000
Last-Modified: Mon, 25 Jul 2016 04:32:39 GMT
Server: Apache

(body)

 

增加 Keep-Alive，設置可以減少NoHttpResponseException

String url = "http://***";
long startTime = System.currentTimeMillis();
//JSONObject json = restTemplate.getForObject("url", JSONObject.class);
HttpHeaders httpHeaders = new HttpHeaders();
httpHeaders.add("Keep-Alive", "timeout=30, max=1000");
JSONObject json = restTemplate.exchange(url, HttpMethod.GET, new HttpEntity<>(null, httpHeaders), JSONObject.class).getBody();