以查询ambari当前用户列表为例：

import cn.chinaunicom.common.constant.Constant;
import com.alibaba.fastjson.JSONObject;
import com.sun.javafx.fxml.builder.URLBuilder;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
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.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import javax.xml.bind.DatatypeConverter;
import java.io.IOException;
import java.net.URISyntaxException;
import java.util.HashMap;
import java.util.Map;

public class test {

    /**
     * http get请求
     */
    public static String doGet(String restUrl, Map<String, String> params) throws ClientProtocolException, IOException {

        CloseableHttpClient httpClient = null;
        CloseableHttpResponse response = null;
        String result = "";
        try {
            // 通过址默认配置创建一个httpClient实例
            httpClient = HttpClients.createDefault();

            URIBuilder uriBuilder = new URIBuilder(restUrl);
            for (Map.Entry<String, String> entry : params.entrySet()) {
                uriBuilder.setParameter(entry.getKey(), entry.getValue());
            }

            // 创建httpGet远程连接实例
            HttpGet httpGet = new HttpGet(restUrl);

            String encoding = null;  //username  password 自行修改  中间":"不可少
            String username = "xxx";
            String password = "xxx";
            encoding = DatatypeConverter.printBase64Binary((username + ":" + password).getBytes("UTF-8"));
            httpGet.setHeader("Authorization", "Basic " + encoding);

            // 设置配置请求参数
            RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(35000)// 连接主机服务超时时间
                    .setConnectionRequestTimeout(35000)// 请求超时时间
                    .setSocketTimeout(60000)// 数据读取超时时间
                    .build();

            // 为httpGet实例设置配置
            httpGet.setConfig(requestConfig);
            // 执行get请求得到返回对象
            response = httpClient.execute(httpGet);
            // 通过返回对象获取返回数据
            HttpEntity entity = response.getEntity();
            // 通过EntityUtils中的toString方法将结果转换为字符串
            result = EntityUtils.toString(entity);
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (URISyntaxException e) {
            e.printStackTrace();
        } finally {
            // 关闭资源
            if (null != response) {
                try {
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (null != httpClient) {
                try {
                    httpClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return result;
    }

    /**
     * 查询用户列表
     */
    public static String ambari_users() throws IOException {
        String url = "http://xx.xx.xx.xx:8080/api/v1/users";
        Map<String, String> params = new HashMap<>();
        params.put("fields", "Users/user_name");
        params.put("sortBy", "Users/user_name.asc");
        params.put("page_size", "10");

        return doGet(url, params);

    }

    public static void main(String[] args) throws IOException {
        System.out.println(ambari_users());
    }

}

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