java Http +json 通讯

        //Map 转 json
        Map jsonMap = new HashMap<>();
        jsonMap.put("username","zhangsan");
        jsonMap.put("pwd","123");
        String contentString = JSONObject.toJSONString(jsonMap);
        //System.out.println(contentString); // {"pwd":"123","username":"zhangsan"}
        
        //解析json Map字符串转为json
        JSonObject jsonObject = JSONObject.parseObject(contentString);
        String username = jsonObject.getString("username");
        String pwd = jsonObject.getString("pwd");
        System.out.println(username);
        System.out.println(pwd);

import com.alibaba.fastjson.JSONObject;

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

public class HttpClientJson {
    public static String post(JSonObject jsonObject, String urls, String encode){
        StringBuffer stringBuffer = new StringBuffer();  
        try{
            //建立URL资源
            URL url = new URL(urls);
            //建立HTTP连接
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            //设置允许输入
            conn.setDoInput(true);
            //设置允许输出
            conn.setDoOutput(true);
            //设置不用缓存 conn.setUseCaches(false);
            //设置传递方式
            conn.setRequestMethod("POST");
            //设置维持长连接
            conn.setRequestProperty("Connection","Keep-Alive");
            //设置文件字符集
            conn.setRequestProperty("Charset","utf-8");
            //将发送参数转换为字节数组
            byte[] data = jsonObject.toString().getBytes(StandardCharsets.UTF_8);
            //设置文件类型
            conn.setRequestProperty("Content-Type","application/json;charset=utf-8");
            //设置连接超时
            conn.setConnectTimeout(10000);
            conn.setReadTimeout(60*1000*2);
            
            //开始连接请求
            conn.connect();
            OutputStream out = new DataOutputStream(conn.getOutputStream());
            //写入请求的字符串
            out.write(data);
            out.flush();
            out.close();
            
            //请求返回的状态
            if (conn.getResponseCode() == HttpURLConnection.HTTP_OK){
                System.out.println("连接成功");
                //请求返回的数据
                InputStream in = conn.getInputStream();
                try{
                    String readline = new String();
                    BufferedReader responseReader = new BufferedReader(new InputStreamReader(in,"utf-8"));
                    while ((readline=responseReader.readLine())!=null){
                        stringBuffer.append(readline);
                    }
                    responseReader.close();
                    System.out.println(stringBuffer.toString());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }else {
                System.out.println("error="+conn.getResponseCode());
            }
            
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

        String url = "";
        //定义Map
        Map jsonMap = new HashMap<>();
        jsonMap.put("username","zhangsan");
        jsonMap.put("pwd","123");
        //把map转换为字符串
        String contentString = JSONObject.toJSONString(jsonMap);
        System.out.println(contentString);
        //Map字符串转为jsonObject
        JSonObject jsonObject = JSONObject.parseObject(contentString);
        //发送POST请求
        String requestBody = HttpClientJson.post(jsonObject,url);
        System.out.println("返回内容"+requestBody);
        //解析返回体
        JSonObject requestJSON = JSONObject.parseObject(requestBody);