URL url = new URL("https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token=" + access_token);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");// 提交模式
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
JSONObject paramJson = new JSONObject();
paramJson.put("scene", userId);//这就是你二维码里携带的参数 String型  名称不可变
paramJson.put("page", "/pages/index/index"); //这是设置扫描二维码后跳转的页面pages/home/home
paramJson.put("width", 280);//默认430，二维码的宽度，单位 px，最小 280px，最大 1280 px
paramJson.put("is_hyaline", true);
paramJson.put("check_path", false);
paramJson.put("env_version", "trial");//正式版为 "release"，体验版为 "trial"，开发版为 "develop"。默认是正式版。
PrintWriter printWriter = new PrintWriter(httpURLConnection.getOutputStream());
printWriter.write(paramJson.toString());
printWriter.flush();
BufferedInputStream bis = new BufferedInputStream(httpURLConnection.getInputStream());
int responseCode = httpURLConnection.getResponseCode();
System.out.println("二维码返回码" + responseCode);
return bis;

这里  responseCode 返回的内容是  200
证明api调用成功，图片已获取到。但是通过 BufferedInputStream 进行存储成图片后，图片变成了损坏状态
小程序已经发布体验版了
求解答：