java获取小程序二维码

• 官方文档地址：https://developers.weixin.qq.com/miniprogram/dev/api-backend/open-api/qr-code/wxacode.get.html
• wxacode.get，生成二维码数量有限制
  
• wxacode.getUnlimited没有二维码数量没有限制，但是路径长度有限制
  

    
    private String getbaseToken(String grantType, String appId, String secret) {
        String baseTokenUrl = "https://api.weixin.qq.com/cgi-bin/token?";
        String url = baseTokenUrl + "grant_type=" + grantType + "&appid=" + appId + "&secret=" + secret;

        WxAccessTokenDto result;
        result = restTemplate.getForObject(url, WxAccessTokenDto.class);
        if (Objects.nonNull(result) && result.getErrcode() == 0) {
            return result.getAccess_token();
        }

        return null;
    }

• 返回的格式是buffer，如果需要返回前端展示需要做处理
• 下面采用byte[] 接收，转成base64返回前端展示

    
    public String getQrImage(WxQrImageRequest request) {
        String appId = "";
        String secret = "";

        //微信授权
        String accessToken = "";
        String result = null;
        accessToken = getbaseToken("client_credential", appId, secret);

        // 获取小程序二维码
        String url = "https://api.weixin.qq.com/wxa/getwxacode?access_token=" + accessToken;
        Map params = new HashMap<>();
        params.put("path", request.getPath());
        params.put("width", request.getWidth());
        params.put("auto_color", request.isAuto_color());
        params.put("line_color", request.getLine_color());
        params.put("is_hyaline", request.is_hyaline());
        
        // 注意这里byte是小写
        ResponseEntity responseEntity = restTemplate.postForEntity(url, params, byte[].class);
        // 二维码图片转base64
        if (responseEntity.getStatusCode() == HttpStatus.OK) {
            InputStream inputStream = null;
            ByteArrayOutputStream swapStream = null;
            try {
                byte[] body = responseEntity.getBody();
                inputStream = new ByteArrayInputStream(body);
                // 将获取流转为base64格式
                byte[] data;
                swapStream = new ByteArrayOutputStream();
                byte[] buff = new byte[1024];
                int rc;
                while ((rc = inputStream.read(buff, 0, 1024)) > 0) {
                    swapStream.write(buff, 0, rc);
                }
                data = swapStream.toByteArray();
                result = new String(base64.getEncoder().encode(data));
                result = "data:image/jpeg;base64," + result;

                return result;
            } catch (Exception e) {

            } finally {
                try {
                    if (inputStream != null) {
                        inputStream.close();
                    }
                    if (swapStream != null) {
                        swapStream.close();
                    }
                } catch (Exception e) {

                }
            }
        }

        return null;
    }