public Map gen(String accessToken) { RestTemplate rest = new RestTemplate();    InputStream inputStream = null;    OutputStream outputStream = null;    try { String url = "https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token="+accessToken;        Map<String,Object> param = new HashMap<>();        param.put("scene", "");        param.put("page", "pages/index/index");        param.put("width", 430);        param.put("auto_color", false);        Map<String,Object> line_color = new HashMap<>();        line_color.put("r", 0);        line_color.put("g", 0);        line_color.put("b", 0);        param.put("line_color", line_color);              MultiValueMap<String, String> headers = new LinkedMultiValueMap<>();        HttpEntity requestEntity = new HttpEntity(param, headers);        ResponseEntity<byte[]> entity = rest.exchange(url, HttpMethod.POST, requestEntity, byte[].class, new Object[0]);        byte[] result = entity.getBody();                FileOutputStream fs = new FileOutputStream("C:/Users/Administrator/Desktop/1.jpg");        FileCopyUtils.copy(new ByteArrayInputStream(result), fs);    } catch (Exception e) { e.printStackTrace();    } finally { } return null; }