/**
 * restTemplate配置
 *
 * @author Songsong
 * @date 2020-08-17 15:09
 */
@Configuration
public class RestTemplateConfiguration {
    @Bean(name = "restTemplate")
    public RestTemplate restTemplate() {
        SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
        //設置連接超時時間1s
        factory.setConnectTimeout(1000);
        //設置讀取時間1s
        factory.setReadTimeout(1000);
        return new RestTemplate(factory);
    }
}

@Resource
private RestTemplate restTemplate;

 public <T> ResponseEntity<T> getForEntity(String url, Class<T> responseType, Object... uriVariables) throws RestClientException {
        RequestCallback requestCallback = this.acceptHeaderRequestCallback(responseType);
        ResponseExtractor<ResponseEntity<T>> responseExtractor = this.responseEntityExtractor(responseType);
        return (ResponseEntity)nonNull(this.execute(url, HttpMethod.GET, requestCallback, responseExtractor, uriVariables));
    }

public <T> ResponseEntity<T> postForEntity(String url, @Nullable Object request, Class<T> responseType, Object... uriVariables) throws RestClientException {
        RequestCallback requestCallback = this.httpEntityCallback(request, responseType);
        ResponseExtractor<ResponseEntity<T>> responseExtractor = this.responseEntityExtractor(responseType);
        return (ResponseEntity)nonNull(this.execute(url, HttpMethod.POST, requestCallback, responseExtractor, uriVariables));
    }

@Slf4j
@Configuration
public class RestTemplateConfiguration {
    @Bean(name = "restTemplate")
    public RestTemplate restTemplate() {
       return getRestTemplate(3, "https://www.baidu.com/......");
    }
    private RestTemplate getRestTemplate(int maxTotal, String preHeatUrl) {
        HttpComponentsClientHttpRequestFactory httpRequestFactory = httpComponentsClientHttpRequestFactory(maxTotal);
        RestTemplate restTemplate = new RestTemplate(httpRequestFactory);
        //解決首次預熱耗時長
        if (StringUtils.isNotEmpty(preHeatUrl)) {
            try {
                restTemplate.postForEntity(preHeatUrl, "", String.class);
            } catch (Exception e) {
                log.error("preHeat url error:{}", e.getMessage());
            }
        }
        return restTemplate;
    }
    /**
     * ClientHttpRequestFactory接口的另一種實現方式（推薦使用），即：
     * HttpComponentsClientHttpRequestFactory：底層使用Httpclient連接池的方式創(chuàng)建Http連接請求
     *
     * @return
     */
    private HttpComponentsClientHttpRequestFactory httpComponentsClientHttpRequestFactory(int maxTotal) {
        //Httpclient連接池，長連接保持時間
        PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(1, TimeUnit.HOURS);
        //設置總連接數
        connectionManager.setMaxTotal(maxTotal);
        //設置同路由的并發(fā)數
        connectionManager.setDefaultMaxPerRoute(maxTotal);
        //設置header
        List<Header> headers = new ArrayList<Header>();
        headers.add(new BasicHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.3; rv:36.0) Gecko/20100101 Firefox/36.04"));
        headers.add(new BasicHeader("Accept-Encoding", "gzip, deflate"));
        headers.add(new BasicHeader("Accept-Language", "zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3"));
        headers.add(new BasicHeader("Connection", "keep-alive"));
        //創(chuàng)建HttpClient
        HttpClient httpClient = HttpClientBuilder.create()
                .setConnectionManager(connectionManager)
                .setDefaultHeaders(headers)
                .setRetryHandler(new DefaultHttpRequestRetryHandler(3, true)) //設置重試次數
                .setKeepAliveStrategy(new DefaultConnectionKeepAliveStrategy()) //設置保持長連接
                .build();
        //創(chuàng)建HttpComponentsClientHttpRequestFactory實例
        HttpComponentsClientHttpRequestFactory requestFactory =
                new HttpComponentsClientHttpRequestFactory(httpClient);
        //設置客戶端和服務端建立連接的超時時間
        requestFactory.setConnectTimeout(10000);
        //設置客戶端從服務端讀取數據的超時時間
        requestFactory.setReadTimeout(5000);
        //設置從連接池獲取連接的超時時間，不宜過長
        requestFactory.setConnectionRequestTimeout(2000);
        //緩沖請求數據，默認為true。通過POST或者PUT大量發(fā)送數據時，建議將此更改為false，以免耗盡內存
        requestFactory.setBufferRequestBody(false);
        return requestFactory;
    }

return restTemplate；

//設置總連接數
 connectionManager.setMaxTotal(maxTotal);