官网地址  http://hc.apache.org/
官方PDF地址: http://hc.apache.org/httpcomponents-core-ga/tutorial/pdf/httpcore-tutorial.pdf
HttpClient是基于HttpCore的HTTP / 1.1兼容HTTP代理实现。 它还为客户端身份验证,HTTP状态管理和HTTP连接管理提供可重用的组件。 HttpComponents Client是Commons HttpClient 3.x的继承者和替代者。 强烈建议Commons HttpClient用户进行升级。
HttpClient 特性
Asynch HttpClient是基于HttpCore NIO和HttpClient组件的HTTP / 1.1兼容HTTP代理实现。 它是Apache HttpClient的补充模块,适用于特殊情况,在特殊情况下,就原始数据吞吐量而言,处理大量并发连接的能力比性能更为重要。
HttpAsyncClient特性
?	超文本传输协议(HTTP)可能是当今Internet上使用的最重要的协议。 Web服务,支持网络的设备和网络计算的增长继续将HTTP协议的作用扩展到用户驱动的Web浏览器之外,同时增加了需要HTTP支持的应用程序的数量。
?	尽管java.net软件包提供了用于通过HTTP访问资源的基本功能,但它并未提供许多应用程序所需的全部灵活性或功能。 HttpClient试图填补这一点通过提供高效,最新且功能丰富的软件包来实现最新的HTTP标准和建议的客户端,从而使此方法无效
?	HttpClient是为扩展而设计的,同时提供对基本HTTP协议的强大支持,对于构建HTTP感知的客户端应用程序(例如Web浏览器,Web服务)的任何人来说,HttpClient可能都会感兴趣客户端或利用或扩展HTTP协议进行分布式通信的系统。
基于HttpCore的客户端HTTP传输库
基于经典(阻塞)I / O
内容不可知
HttpClient不是浏览器。 它是客户端HTTP传输库。 HttpClient的目的是传输和接收HTTP消息,HttpClient将不会尝试处理内容,执行HTML页面中嵌入的javascript,尝试猜测内容类型(如果未显式设置),重新格式化请求/重写位置URI或其他与HTTP传输无关的功能。
最新Pom引入
   <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpasyncclient</artifactId>
            <version>4.1.4</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.10</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpmime</artifactId>
            <version>4.5.10</version>
        </dependency>


HttpClient连接池简单封装
支持https 无须认证请求
import com.alibaba.fastjson.JSONObject;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.config.SocketConfig;
import org.apache.http.conn.DnsResolver;
import org.apache.http.conn.HttpConnectionFactory;
import org.apache.http.conn.ManagedHttpClientConnection;
import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.NoopHostnameVerifier;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.TrustSelfSignedStrategy;
import org.apache.http.entity.ByteArrayEntity;
import org.apache.http.entity.ContentType;
import org.apache.http.impl.DefaultConnectionReuseStrategy;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.DefaultConnectionKeepAliveStrategy;
import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.DefaultHttpResponseParserFactory;
import org.apache.http.impl.conn.ManagedHttpClientConnectionFactory;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.impl.conn.SystemDefaultDnsResolver;
import org.apache.http.impl.io.DefaultHttpRequestWriterFactory;
import org.apache.http.ssl.SSLContexts;
import org.apache.http.util.EntityUtils;
import javax.net.ssl.SSLContext;
import java.io.IOException;
import java.net.URI;
import java.nio.charset.Charset;
import java.util.concurrent.TimeUnit;
/**
 * @author Created by niugang on 2020/3/25/15:13
 * HttpClient实现应该是线程安全的。 建议将此类的相同实例重用于多个请求执行。
 */
public class HttpClientUtils {
    public static CloseableHttpClient httpClient = null;
    public static PoolingHttpClientConnectionManager manager = null;
    /**
     * 获取HttpClient工具类
     *
     * @return CloseableHttpClient
     * @throws Exception Exception
     */
    public static synchronized CloseableHttpClient getHttpClient() throws Exception {
        if (httpClient == null) {
            //ssl 连接设置 无须证书也能访问 https
            SSLContext sslContext = SSLContexts.custom()
                    .loadTrustMaterial(null, new TrustSelfSignedStrategy())
                    .build();
            // 该主机名验证程序实际上关闭了主机名验证。 它接受任何有效的SSL会话并匹配目标主机
            SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext, NoopHostnameVerifier.INSTANCE);
            //为支持的协议方案创建自定义连接套接字工厂的注册表。
            Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create()
                    .register("http", PlainConnectionSocketFactory.INSTANCE)
                    .register("https", sslsf)
                    .build();
            //HTTPConnection工厂 :配置请求/解析响应
            HttpConnectionFactory<HttpRoute, ManagedHttpClientConnection> connFactory = new ManagedHttpClientConnectionFactory(
                    DefaultHttpRequestWriterFactory.INSTANCE, DefaultHttpResponseParserFactory.INSTANCE);
            //DNS解析器
            DnsResolver dnsResolver = SystemDefaultDnsResolver.INSTANCE;
            //创建池化管理器
            manager = new PoolingHttpClientConnectionManager(
                    socketFactoryRegistry, connFactory, dnsResolver);
            // 默认为Socket配置
            SocketConfig socketConfig = SocketConfig.custom()
                    .setTcpNoDelay(true)
                    .build();
            manager.setDefaultSocketConfig(socketConfig);
            // 配置永久连接的最大总数或每个路由限制
            // 可以保留在池中或由连接管理器租用。
            //每个路由的默认最大连接,每个路由实际最大连接为默认为DefaultMaxPreRoute控制,而MaxTotal是控制整个池子最大数
            manager.setMaxTotal(100);
            manager.setDefaultMaxPerRoute(10);
            // 在从连接池获取连接时,连接不活跃多长时间后需要进行一次验证,默认为2s
            manager.setValidateAfterInactivity(5 * 1000);
            //默认请求配置
            //设置连接超时时间 4s
            //设置等待数据超时时间,5s
            //设置从连接池获取连接的等待超时时间
            RequestConfig defaultRequestConfig = RequestConfig.custom()
                    .setConnectTimeout(4 * 1000)
                    .setSocketTimeout(5 * 1000)
                    .setConnectionRequestTimeout(2000)
                    .build();
            httpClient = HttpClients.custom()
                    .setConnectionManager(manager)
                    .setDefaultRequestConfig(defaultRequestConfig)
                    //连接池不是共享模式
                    .setConnectionManagerShared(false)
                    .evictIdleConnections(60, TimeUnit.SECONDS)
                    //定期回收空闲连接
                    .evictExpiredConnections()
                    .setConnectionTimeToLive(60, TimeUnit.SECONDS)
                    //连接重用策略,即是否能keeplive
                    .setConnectionReuseStrategy(DefaultConnectionReuseStrategy.INSTANCE)
                    //长连接配置,即获取长连接生产多长时间
                    .setKeepAliveStrategy(DefaultConnectionKeepAliveStrategy.INSTANCE)
                    //设置重试次数,默认为3次;当前禁用掉(根据需要重启)
                    .setRetryHandler(new DefaultHttpRequestRetryHandler(0, false))
                    .build();
            Runtime.getRuntime().addShutdownHook(new Thread() {
                @Override
                public void run() {
                    try {
                        httpClient.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            });
        }
        return httpClient;
    }
    public static void main(String[] args) throws Exception {
        //####1.HTTPS get请求验证
        URI uri = new URIBuilder()
                .setScheme("https")
                .setHost("11.12.115.104")
                .setPath("/api/serverStatus/serverInfo")
                .build();
        HttpGet httpsget = new HttpGet(uri);
        // 自定义响应处理器
        ResponseHandler<String> responseHandler = new ResponseHandler<String>() {
            @Override
            public String handleResponse(
                    final HttpResponse response) throws IOException {
                int status = response.getStatusLine().getStatusCode();
                if (status >= 200 && status < 300) {
                    HttpEntity entity = response.getEntity();
                    return entity != null ? EntityUtils.toString(entity, Charset.forName("UTF-8")) : null;
                } else {
                    throw new ClientProtocolException("Unexpected response status: " + status + "->" + response.getStatusLine().getReasonPhrase());
                }
            }
        };
        String httpsGetExecute = getHttpClient().execute(httpsget, responseHandler);
        System.out.println("https get excute result " + httpsGetExecute);
        //####2.Https Post请求验证  请求体为json数据
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("user", "3333");
        jsonObject.put("ip", "192.168.1.3");
        jsonObject.put("status", "0");
        ByteArrayEntity byteArrayEntity = new ByteArrayEntity(jsonObject.toJSONString().getBytes(), ContentType.create("application/json", "UTF-8"));
        HttpPost httpspost = new HttpPost("https://11.12.115.104/api/accessControl/saveDevice.do");
        httpspost.setHeader("token", "63be0354c964fffd481f5dc5b5ca25e7");
        httpspost.setEntity(byteArrayEntity);
        String httpsGostExecute = getHttpClient().execute(httpspost, responseHandler);
        System.out.println("https post excute result " + httpsGostExecute);
       //####3.http get
        HttpGet httpGet = new HttpGet("http://www.baidu.com");
        String httpGetExecute = getHttpClient().execute(httpGet, responseHandler);
        System.out.println("http get excute result " + httpGetExecute);
    }
}
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Apache HttpClient和HttpAsyncClient应用
原文:https://www.cnblogs.com/niugang0920/p/12567565.html