配置中心长轮询实现中怎样实现客户端？

@Slf4j public class ConfigClient {

private CloseableHttpClient httpClient; private RequestConfig requestConfig;

public ConfigClient() { this.httpClient = HttpClientBuilder.create().build(); // ① httpClient 客户端超时时间要大于长轮询约定的超时时间 this.requestConfig = RequestConfig.custom().setSocketTimeout(40000).build(); }

@SneakyThrows public void longPolling(String url, String dataId) { String endpoint = url + "?dataId=" + dataId; HttpGet request = new HttpGet(endpoint); CloseableHttpResponse response = httpClient.execute(request); switch (response.getStatusLine().getStatusCode()) { case 200: { BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity() .getContent())); StringBuilder result = new StringBuilder(); String line; while ((line = rd.readLine()) != null) { result.append(line); } response.close(); String configInfo = result.toString(); log.info("dataId: [{}] changed, receive configInfo: {}", dataId, configInfo); longPolling(url, dataId); break; } // ② 304 响应码标记配置未变更 case 304: { log.info("longPolling dataId: [{}] once finished, configInfo is unchanged, longPolling again", dataId); longPolling(url, dataId); break; } default: { throw new RuntimeException("unExcepted HTTP status code"); } }

}

public static void main(String[] args) { // httpClient 会打印很多 debug 日志，关闭掉 Logger logger = (Logger)LoggerFactory.getLogger("org.apache.http"); logger.setLevel(Level.INFO); logger.setAdditive(false);

ConfigClient configClient = new ConfigClient(); // ③ 对 dataId: user 进行配置监听 configClient.longPolling("http://127.0.0.1:8080/listener", "user"); }

}