Spring Rest模板-204内容来自Web服务

Question

I have a rest service and is consumed using Spring's RestTemplate with Apache HttpClient as,

    @Autowired
    public ClientImpl(@Value("${base-uri}") final String baseUrl,
                              @Qualifier("restOperations") RestOperations restTemplate) {
        serviceUrl = baseUrl;
        restTemplate = restTemplate;
    }

   private List<ResponseDetails> processRequest(CustomRequest request) throws Exception {
    ResponseEntity<ResponseDetails[]> responseEntity = restTemplate.exchange(serviceUrl, HttpMethod.POST, entity, ResponseDetails[].class);
    if (responseEntity.getStatusCode().value() == 204) {
        return Collections.<ResponseDetails>emptyList();
    }
    ResponseDetails[] response = responseEntity.getBody();
    return response != null ? Lists.newArrayList(response) : Collections.<ResponseDetails>emptyList();
}

When the webservice returns 204 response, then the second service call after 204 response, fails with read timeout.

Spring-web : 4.3.5

I cannot figure out the cause. Any help?

EDIT: From debug logs,

org.apache.http.impl.conn.DefaultHttpResponseParser;Garbage in response: ÿþ{"id":0}HTTP/1.1 204 Could not find

Response in server logs by httpclient:

<204 No Content,{Cache-Control=[no-cache], Pragma=[no-cache], Content-Type=[application/json; charset=utf-16], Expires=[-1], Server=[some], X-AspNet-Version=[someversion], X-Powered-By=[ASP.NET], Date=[somedate]}>

Answer 1

HTTP 204 is status code for "No Content", but there seems to be garbage content in the response. This can be seen on your logs:

ÿþ{"id":0}

This is the cause of problems you have.

HTTP client is not expecting anything in the body content of 204 response so does not read it, hence response handler does not see that there is any garbage. However since there is garbage which is not yet consumed the connection stays open until it is read -> the next connection, which tries to reuse the connection, gets hit with a read timeout.

There is a separate thread about a similar problem , where the problem is worked around with a custom HTTP request executor. Using such executor, you could call getBody() to obtain the garbage response body and then next request would not have any issues.