这个例子使用的是Apache HttpClient 4.5.7版本

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.7</version>
</dependency>

import com.alibaba.fastjson.JSON;
import org.apache.commons.beanutils.BeanMap;
import org.apache.commons.beanutils.BeanUtils;
import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * @author Jack
 * @date 2019年3月12日 下午4:56:14
 * @version 1.0.0
 */
public class HttpClientUtils {

    /**
     *
     * @param protocol  协议
     * @param hostname  域名或者IP地址
     * @param port  端口
     * @param path  路径 如   /aa/query
     * @param request   入参
     * @param resCla   返回结果对象的类字面量
     * @param <Y>
     * @param <T>
     * @return  返回对应的结果对象
     * @throws Exception
     */
    public static  <Y,T> Y alaPost(String protocol, String hostname, String port, String path, T request,Class<Y> resCla) throws Exception{
        String result=post( protocol,  hostname,  port,  path, request);
        Y response=resCla.newInstance() ;
        try {
            Map<String, Object> resMap = JSON.parse(result, Map.class);
            //map转bean
            BeanUtils.populate(response,resMap );
        } catch (Exception e) {
            throw new Exception("error");
        }
        return response;
    }

    /**
     *
     * @param protocol  协议
     * @param hostname  域名或者IP地址
     * @param port  端口
     * @param path  路径 如   /aa/query
     * @param request   入参
     * @param <T>
     * @return   字符串形式的返回结果
     * @throws Exception
     */
    public static <T> String post(String protocol, String hostname, String port, String path, T request)
            throws Exception {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        // url路径
        HttpPost httpPost = new HttpPost(
                protocol + "://" + hostname + ":" + port + path);
        List<NameValuePair> nvps = new ArrayList<>();

        // 设置参数
        //bean转map
        BeanMap map=new BeanMap(request);
        map.forEach((k, v) -> nvps.add(new BasicNameValuePair( k.toString(), v.toString())));
        // 设置参数编码
        httpPost.setEntity(new UrlEncodedFormEntity(nvps, "utf-8"));
        CloseableHttpResponse response = httpclient.execute(httpPost);
        if (HttpStatus.SC_OK != response.getStatusLine().getStatusCode()) {
            throw new Exception("error");
        }
        String result ;
        try {
            HttpEntity entity = response.getEntity();
            // 获取返回结果
            result = EntityUtils.toString(entity);
            //关闭流
            EntityUtils.consume(entity);
        } finally {
            response.close();
        }
        return result;
    }

}