这个是httpClient的get请求写法，一般需求应该是够用了。
参考了几个博客的代码，具体的网址忘记了，有问题可以联系我。
代码：
package com.demo.service.impl;

import com.demo.service.HttpRequestGetService;
import com.demo.utils.CloseHttpUtil;
import org.apache.http.HttpEntity;
import org.apache.http.ParseException;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import org.springframework.stereotype.Component;

import java.io.IOException;
import java.net.URISyntaxException;
import java.util.Map;

@Component
public class HttpRequestGetServiceImpl implements HttpRequestGetService {
    CloseHttpUtil closeHttpUtil = new CloseHttpUtil();

    public String doGetRequest(String url, Map<String, String> headMap, Map<String, String> paramMap) {
        // 获取连接客户端工具
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String entityStr = null;
        CloseableHttpResponse response = null;
        try {
            /*
             * 由于GET请求的参数都是拼装在URL地址后方，所以我们要构建一个URL，带参数
             */
            URIBuilder uriBuilder = new URIBuilder(url);
            for (Map.Entry<String, String> param : paramMap.entrySet()) {
                uriBuilder.addParameter(param.getKey(), param.getValue());
            }
            // 根据带参数的URI对象构建GET请求对象
            HttpGet httpGet = new HttpGet(uriBuilder.build());

        /*
         * 添加请求头信息
         */
            for (Map.Entry<String, String> header : headMap.entrySet()) {
                httpGet.addHeader(header.getKey(), header.getValue());
            }
            /*httpGet.addHeader("Content-Type", "application/VIID+JSON;charset=utf8");
            httpGet.addHeader("User-Identify","12345678905030000000");*/
            closeHttpUtil.setTimeOut(httpGet);
            // 执行请求
            response = httpClient.execute(httpGet);
            // 获得响应的实体对象
            HttpEntity entity = response.getEntity();
            // 使用Apache提供的工具类进行转换成字符串
            entityStr = EntityUtils.toString(entity, "UTF-8");
        } catch (ClientProtocolException e) {
            System.err.println("Http协议出现问题");
            e.printStackTrace();
        } catch (ParseException e) {
            System.err.println("解析错误");
            e.printStackTrace();
        } catch (URISyntaxException e) {
            System.err.println("URI解析异常");
            e.printStackTrace();
        } catch (IOException e) {
            System.err.println("IO异常");
            e.printStackTrace();
        } finally {
            // 释放连接
            closeHttpUtil.close(response, httpClient);
        }

        return entityStr;
    }

    public String doGetRequestNoparam(String url, Map<String, String> headMap) {
        // 获取连接客户端工具
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String entityStr = null;
        CloseableHttpResponse response = null;
        try {
            /*
             * 由于GET请求的参数都是拼装在URL地址后方，所以我们要构建一个URL，带参数
             */
            URIBuilder uriBuilder = new URIBuilder(url);
            // 根据带参数的URI对象构建GET请求对象
            HttpGet httpGet = new HttpGet(uriBuilder.build());
        /*
         * 添加请求头信息
         */
            for (Map.Entry<String, String> header : headMap.entrySet()) {
                httpGet.addHeader(header.getKey(), header.getValue());
            }
            /*httpGet.addHeader("Content-Type", "application/VIID+JSON;charset=utf8");
            httpGet.addHeader("User-Identify","12345678905030000000");*/
            closeHttpUtil.setTimeOut(httpGet);
            // 执行请求
            response = httpClient.execute(httpGet);
            // 获得响应的实体对象
            HttpEntity entity = response.getEntity();
            // 使用Apache提供的工具类进行转换成字符串
            entityStr = EntityUtils.toString(entity, "UTF-8");
        } catch (ClientProtocolException e) {
            System.err.println("Http协议出现问题");
            e.printStackTrace();
        } catch (ParseException e) {
            System.err.println("解析错误");
            e.printStackTrace();
        } catch (URISyntaxException e) {
            System.err.println("URI解析异常");
            e.printStackTrace();
        } catch (IOException e) {
            System.err.println("IO异常");
            e.printStackTrace();
        } finally {
            // 释放连接
            closeHttpUtil.close(response, httpClient);
        }
        return entityStr;
    }

    public String doGetRequestStringParam(String url, Map<String, String> headMap, String param) {
        // 获取连接客户端工具
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String entityStr = null;
        CloseableHttpResponse response = null;
        try {
            /*
             * 由于GET请求的参数都是拼装在URL地址后方，所以我们要构建一个URL，带参数
             */
            URIBuilder uriBuilder = new URIBuilder(url);
            // 根据带参数的URI对象构建GET请求对象
            HttpGet httpGet = new HttpGet(uriBuilder.build() + param);
            System.out.println("调用String参数的URL:" + httpGet);
        /*
         * 添加请求头信息
         */
            for (Map.Entry<String, String> header : headMap.entrySet()) {
                httpGet.addHeader(header.getKey(), header.getValue());
            }
            closeHttpUtil.setTimeOut(httpGet);
            response = httpClient.execute(httpGet);
            // 获得响应的实体对象
            HttpEntity entity = response.getEntity();
            // 使用Apache提供的工具类进行转换成字符串
            entityStr = EntityUtils.toString(entity, "UTF-8");
        } catch (ClientProtocolException e) {
            System.err.println("Http协议出现问题");
            e.printStackTrace();
        } catch (ParseException e) {
            System.err.println("解析错误");
            e.printStackTrace();
        } catch (URISyntaxException e) {
            System.err.println("URI解析异常");
            e.printStackTrace();
        } catch (IOException e) {
            System.err.println("IO异常");
            e.printStackTrace();
        } finally {
            // 释放连接
            closeHttpUtil.close(response, httpClient);

        }
        return entityStr;
    }

    public String doGetRequestIntParam(String url, Map<String, String> headMap, int RecordStartNo, int PageRecordNum) {
        // 获取连接客户端工具
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String entityStr = null;
        CloseableHttpResponse response = null;
        try {
            /*
             * 由于GET请求的参数都是拼装在URL地址后方，所以我们要构建一个URL，带参数
             */
            URIBuilder uriBuilder = new URIBuilder(url);
            // 根据带参数的URI对象构建GET请求对象
            HttpGet httpGet = new HttpGet(uriBuilder.build() + "?" + "RecordStartNo=" + RecordStartNo + "&" + "PageRecordNum=" + PageRecordNum);
            System.out.println("调用String参数的URL:" + httpGet);
        /*
         * 添加请求头信息
         */
            for (Map.Entry<String, String> header : headMap.entrySet()) {
                httpGet.addHeader(header.getKey(), header.getValue());
            }
            closeHttpUtil.setTimeOut(httpGet);
            response = httpClient.execute(httpGet);
            // 获得响应的实体对象
            HttpEntity entity = response.getEntity();
            // 使用Apache提供的工具类进行转换成字符串
            entityStr = EntityUtils.toString(entity, "UTF-8");
        } catch (ClientProtocolException e) {
            System.err.println("Http协议出现问题");
            e.printStackTrace();
        } catch (ParseException e) {
            System.err.println("解析错误");
            e.printStackTrace();
        } catch (URISyntaxException e) {
            System.err.println("URI解析异常");
            e.printStackTrace();
        } catch (IOException e) {
            System.err.println("IO异常");
            e.printStackTrace();
        } finally {
            // 释放连接
            closeHttpUtil.close(response, httpClient);
        }
        return entityStr;
    }
}
__________________________________________________________________

import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.impl.client.CloseableHttpClient;

import java.io.IOException;

public class CloseHttpUtil {
    public static void close(CloseableHttpResponse response, CloseableHttpClient httpClient) {
        if (null != response) {
            try {
                response.close();
                httpClient.close();
            } catch (IOException e) {
                System.err.println("释放连接出错");
                e.printStackTrace();
            }
        }
    }

    public static void setTimeOut(HttpGet httpGet) {
        RequestConfig requestConfig = RequestConfig.custom()
                // 设置连接超时时间(单位毫秒)
                .setConnectTimeout(10000)
                // 设置请求超时时间(单位毫秒)
                .setConnectionRequestTimeout(10000)
                // socket读写超时时间(单位毫秒)
                .setSocketTimeout(10000)
                // 设置是否允许重定向(默认为true)
                .setRedirectsEnabled(true).build();

        // 将上面的配置信息 运用到这个Get请求里
        httpGet.setConfig(requestConfig);
    }