1、HttpURLConnection 获取小程序码连接

// 获取accessToken，详情查看小程序文档result为http调用返回，不同的http工具返回结构不同
String accessToken = result.get("access_token").toString();

URL url = new URL("https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token="+accessToken);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");// 提交模式
// conn.setConnectTimeout(10000);//连接超时 单位毫秒
// conn.setReadTimeout(2000);//读取超时 单位毫秒
// 发送POST请求必须设置如下两行
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
// 获取URLConnection对象对应的输出流，调用微信api
PrintWriter printWriter = new PrintWriter(httpURLConnection.getOutputStream());
// 获取小程序码的必传参数scene
JSONObject paramJson = new JSONObject(); paramJson.put("scene", scene);
printWriter.write(paramJson.toString());
printWriter.flush();

2、处理HttpURLConnection输入流，微信api返回值

File file = new File("小程序直播码.png");
InputStream in = httpURLConnection.getInputStream();
BufferedImage bufferedImage = ImageIO.read(in);
ImageIO.write(bufferedImage, "png", file);

System.out.println(file.getAbsolutePath());