一般作为工具类进行使用，POST请求需要带json格式的请求体，GET请求返回json格式的响应

package cn.omvn.utils;

/**
 * 2023-10-05
 * 栋dong
 */

import com.alibaba.fastjson.JSONObject;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;

public class HttpUtil {
    /**
     * GET 方式的http请求
     *
     * @param httpUrl 请求地址
     * @return 返回结果
     */
    public static String doGet(String httpUrl) {
        HttpURLConnection connection = null;
        InputStream inputStream = null;
        BufferedReader bufferedReader = null;
        String result = null;// 返回结果字符串
        try {
            // 创建远程url连接对象
            URL url = new URL(httpUrl);
            // 通过远程url连接对象打开⼀个连接，强转成httpURLConnection
            connection = (HttpURLConnection) url.openConnection();
            // 设置连接⽅式：get
            connection.setRequestMethod("GET");
            // 设置连接主机服务器的超时时间：15000毫秒
            connection.setConnectTimeout(15000);
            // 设置读取远程返回的数据时间：60000毫秒
            connection.setReadTimeout(60000);
            // 发送请求
            connection.connect();
            // 通过connection连接，获取输⼊流
            if (connection.getResponseCode() == 200) {
                inputStream = connection.getInputStream();
                // 封装输⼊流，并指定字符集
                bufferedReader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8));
                // 存放数据
                StringBuilder sbf = new StringBuilder();
                String temp;
                while ((temp = bufferedReader.readLine()) != null) {
                    sbf.append(temp);
                    sbf.append(System.getProperty("line.separator"));
                }
                result = sbf.toString();
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭资源
            if (null != bufferedReader) {
                try {
                    bufferedReader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (null != inputStream) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (connection != null) {
                connection.disconnect();// 关闭远程连接
            }
        }
        return result;
    }

    /**
     * post 方式的http请求
     * @param httpUrl 请求地址
     * @param jsonInputString   请求参数
     * @return 返回结果
     */
    public static JSONObject doPost(String httpUrl, String jsonInputString) {
        try {
            // 创建URL对象
            URL url = new URL(httpUrl);

            // 打开连接
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            // 设置请求方法为POST
            connection.setRequestMethod("POST");

            // 启用输入和输出流
            connection.setDoOutput(true);
            connection.setDoInput(true);

            // 设置请求头信息
            connection.setRequestProperty("Content-Type", "application/json");
            connection.setRequestProperty("Accept", "application/json");

            // 写入JSON数据
            try (OutputStream os = connection.getOutputStream()) {
                byte[] input = jsonInputString.getBytes("utf-8");
                os.write(input, 0, input.length);
            }

            // 获取响应代码
            int responseCode = connection.getResponseCode();

            // 读取响应数据
            if (responseCode == 200) {
                StringBuilder response = new StringBuilder();
                try (InputStreamReader reader = new InputStreamReader(connection.getInputStream(), "utf-8"); BufferedReader in = new BufferedReader(reader)) {

                    String line;
                    while ((line = in.readLine()) != null) {
                        response.append(line);
                    }
                }

                return JSONObject.parseObject(response.toString());
            } else {
                // 处理请求失败的情况
                throw new RuntimeException("Request failed with response code: " + responseCode);
            }
        } catch (Exception e) {
            throw new RuntimeException("Error: " + e.getMessage());
        }
    }
}