Java后端使用http post，get请求

package com.fjnu.utils;

import com.alibaba.fastjson.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class httpClient {
    public static String sendGet(String url, String param) {
        String result = "";
        BufferedReader in = null;
        try {
            String urlNameString = url + "?" + param;
            URL realUrl = new URL(urlNameString);
            // 打开和URL之间的连接
            URLConnection connection = realUrl.openConnection();
            // 设置通用的请求属性
            connection.setRequestProperty("accept", "*/*");
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 建立实际的连接
            connection.connect();
            // 获取所有响应头字段
            Map<String, List<String>> map = connection.getHeaderFields();
            // 遍历所有的响应头字段
            for (String key : map.keySet()) {
                System.out.println(key + "--->" + map.get(key));
            }
            // 定义 BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println("发送GET请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 向指定 URL 发送POST方法的请求
     *
     * @param url   发送请求的 URL
     * @param param 请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
     * @return 所代表远程资源的响应结果
     */
    public static String sendPost(String url, Map<String,Object> param,String theRealParam) {
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        url=url+"&"+theRealParam;
        try {
            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            URLConnection conn = realUrl.openConnection();
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "application/json, text/javascript, */*; q=0.01");
            //设置请求类型，注意第三方文档接口的要求，一定要保持一致
            conn.setRequestProperty("Content-Type", "text/html;charset=utf-8");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            out = new PrintWriter(conn.getOutputStream());
            JSONObject jsonObject = new JSONObject(param);
            //配置
            jsonObject.put("grant_type", "client_credentials");
            jsonObject.put("client_id", "YXA6_9BOlrnhSWSb-FUk0fvzqw");
            jsonObject.put("client_secret", "YXA6FIe8F_euvzf-NosJ7nXCx-MMosk");
            out.print(jsonObject);
            // flush输出流的缓冲
            out.flush();
            // 定义BufferedReader输入流来读取URL的响应,注意这里一定需要设置utf-8，这可以从根本上解决乱码问题！
            in = new BufferedReader(new InputStreamReader(conn.getInputStream(),"utf-8"));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println("发送 POST 请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输出流、输入流
        finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result;
    }

    public static void main(String[] args) {
        HashMap<String, Object> map = new HashMap<>();
        map.put("studyId","201911111000019");
        //使用post请求来获得接口返回的json数据
        String sr = sendPost("http://m.fjcyl.com/admin/cylOrgMembers/selectCurrentStudy?current=&PAGE_SIZE=41&CURRENT_PAGE=1&orgId=199060",
                map,"studyId=201911111000019");
        System.out.println(sr);
    }
}

这里，

in = new BufferedReader(new InputStreamReader(conn.getInputStream(),"utf-8"));

一定要设置utf-8，这可以从根本上解决乱码问题！