https://hc.apache.org/index.html

配置依赖

    implementation group: 'org.apache.httpcomponents', name: 'httpclient', version: '4.5.13'
    implementation group: 'org.apache.httpcomponents', name: 'httpcore', version: '4.4.12'
    implementation group: 'org.apache.httpcomponents', name: 'httpasyncclient', version: '4.1.4'
    implementation group: 'org.apache.httpcomponents', name: 'httpcore-nio', version: '4.4.12'

        var credProvider = new BasicCredentialsProvider();
        credProvider.setCredentials(
            new AuthScope(host, port),
            new UsernamePasswordCredentials(username, password));

        var connManager = new PoolingHttpClientConnectionManager();
        connManager.setMaxTotal(100);
        connManager.setDefaultMaxPerRoute(100);
        connManager.setValidateAfterInactivity(3000);

        var requestConfig = RequestConfig.custom()
            .setConnectionRequestTimeout(1000)
            .setConnectTimeout(2000)
            .setSocketTimeout(3000)
            .build();

        var httpClient = HttpClients.custom()
            .setDefaultCredentialsProvider(credProvider)
            .setConnectionManager(connManager)
            .setDefaultRequestConfig(requestConfig)
            .evictExpiredConnections()
            .evictIdleConnections(180, TimeUnit.SECONDS)
            .build();

参数配置说明:
httpclient支持连接池化, 在进行http请求的时候, 需要建立tcp连接, 要经过三次握手, 所以为了复用tcp连接, 就需要池化连接, 池化连接是针对HttpHost 这个类的(由connMgr.setMaxPerRoute()的参数是HttpHost类型可知)的, 既可以是ip:port, 也可以是hostname:port. 如果是后者, 则这一整个域名背后所有的ip共享一个route的limit限制.
setMaxTotal : 设置一共可以建立的连接个数, 过多的会造成被访问节点的负担, 过少影响请求方的效率
setDefaultMaxPerRoute: 设置每个route默认的最大连接数
setMaxPerRoute(HttpHost, Integer) : 可以覆盖default值, 为某个route设置连接数
setConnectionRequestTimeout : 从连接池获取连接超时
setConnectTimeout: 连接超时
setSocketTimeout: 读超时

参考:
https://www.cnblogs.com/trust-freedom/p/6349502.html
https://blog.csdn.net/wujun2412/article/details/120704886
感谢分享