How to generate sun code for WeChat applet in Java

public static String getAccessToken(String appid, String appsecret)
    {
        String requestUrl = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid="+appid+"&secret="+appsecret+"";
        String accessToken = null;
        try
        {
            String response = HttpClientUtil.getInstance().sendHttpsGet(
                    requestUrl, null);
            JSONObject json = JSONObject.parseObject(response);
            accessToken = String.valueOf(json.get("access_token"));
        }
        catch (Exception e)
        {
            logger.error("getAccessToken error", e);
        }

        return accessToken;
    }

 public static String generatLimitSunCode(WxScanCodeParam param) throws Exception 
    {
       String token =param.getAccessToken();
       Map<String, String> params = new HashMap<>();
       params.put("path", param.getPath());
       params.put("width", "430");
       CloseableHttpClient httpClient = HttpClientBuilder.create().build();
       HttpPost httpPost = new HttpPost("https://api.weixin.qq.com/wxa/getwxacode?access_token="+token);
       httpPost.addHeader(HTTP.CONTENT_TYPE, "application/json");
       String body = JSON.toJSONString(params);
       StringEntity entity = new StringEntity(body);
       entity.setContentType("image/jpg");
       httpPost.setEntity(entity);
       HttpResponse response = httpClient.execute(httpPost);
       int statusCode = response.getStatusLine().getStatusCode();
       if (statusCode == HttpStatus.SC_OK) 
       {
           HttpEntity entity2 = response.getEntity();
           if(!entity2.getContentType().getValue().equals("image/jpeg"))
           {
               String result = EntityUtils.toString(entity2, "UTF-8");
               logger.error("generate sun code error,http execute result:" + result);
               return null;
           }
       }
       else
       {
           logger.error("generate sun code error,http execute result:" + statusCode);
       }
       
       InputStream inputStream = response.getEntity().getContent();
        // 保存图片到本地     
       int flag = saveImg(inputStream, param.getFilePath(), name);
       if (flag == 0)
       {
           throw new SysException("保存图片[" + name + "]失败");
       }
       else
       {
           logger.info("太阳码[{}]生成成功", name);
       }
       return param.getFilePath() + File.separatorChar + name;
   }

/**
     * 生成无限制的小程序码
     * @param param
     * @return
     * @throws Exception
     */
    public static String generatUnlimitSunCode(WxScanCodeParam param) throws Exception 
    {
       String token =param.getAccessToken();
       Map<String, String> params = new HashMap<>();
       params.put("scene", param.getScene());
       params.put("page", param.getPath());
       params.put("width", "430");
       CloseableHttpClient httpClient = HttpClientBuilder.create().build();
       HttpPost httpPost = new HttpPost("https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token="+token);
       httpPost.addHeader(HTTP.CONTENT_TYPE, "application/json");
       String body = JSON.toJSONString(params);
       StringEntity entity = new StringEntity(body);
       entity.setContentType("image/jpg");
       httpPost.setEntity(entity);
       HttpResponse response = httpClient.execute(httpPost);
       int statusCode = response.getStatusLine().getStatusCode();
       if (statusCode == HttpStatus.SC_OK) 
       {
           HttpEntity entity2 = response.getEntity();
           if(!entity2.getContentType().getValue().equals("image/jpeg"))
           {
               String result = EntityUtils.toString(entity2, "UTF-8");
               logger.error("generate sun code error,http execute result:" + result);
               return null;
           }
       }
       else
       {
           logger.error("generate sun code error,http execute result:" + statusCode);
       }
       
       InputStream inputStream = response.getEntity().getContent();
       
       //太阳码写标题
       String content=param.getWriteContent();
       if(StringUtil.isNotEmpty(content) && param.isWrite())
       {
          inputStream = ImageUtil.addImageTitle(param.getWriteContent(), inputStream, 450, 450);
       }
      
       String name = param.getFileName()+".jpg";//文件名加后缀，跟上面对应
       

       int flag = saveImg(inputStream, param.getFilePath(), name);// 保存图片
       if (flag == 0)
       {
           throw new SysException("保存图片[" + name + "]失败");
       }
       else
       {
           logger.info("太阳码[{}]生成成功", name);
       }
       return param.getFilePath() + File.separatorChar + name;
   }