小程序图片上传到COS，求提供完整的前端+后端java计算签名代码

//java后端计算签名
    public static String signateForCOS(String method,String key) {
        try {
            String bucketName = BUCKET_NAME;
            COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
            COSSigner signer = new COSSigner();
            //设置过期时间为 1 个小时
            Date expiredTime = new Date(System.currentTimeMillis() + 3600L * 1000L);
            // 要签名的 key, 生成的签名只能用于对应此 key 的上传
            //String key = "/userImage";
            HttpMethodName methodName = null;
            switch(method.toLowerCase()){
                case "post":
                    methodName = HttpMethodName.POST;
                    break;

                case "get":
                    methodName = HttpMethodName.GET;
                    break;
                case "put":
                    methodName = HttpMethodName.PUT;
                    break;
            }

            String sign = signer.buildAuthorizationStr(methodName, key, cred, expiredTime);
            logger.info("参数信息："+methodName+"  "+key);
            logger.info("/userImage算的签名信息是：{}", sign);
            return sign;
        } catch (Exception e) {
            logger.error("signateForCOS error ,info is " + e);
        }
        return "";

    } 

 var cos = new COS({
  getAuthorization: function(params, callback) { //获取签名 必填参数

    // 方法一（推荐）服务器提供计算签名的接口

    wx.request({
      url: app.globalData.urlPath + '/wechat/getSign',
      data: {
        Method: params.Method,
        Key: params.Key
      },
      dataType: 'text',
      success: res => {
        var res = res.data
        console.log("接口返回结果："+res)
        //var json = JSON.parse(res);
        //console.log("签名信息：" + res['data'])
        callback(res);
      }
    });

    // 方法二（适用于前端调试）
    /** 
    var authorization = COS.getAuthorization({
      SecretId: config.SecretId,
      SecretKey: config.SecretKey,
      Method: params.Method,
      Key: params.Key
    });
    console.log("authorization is "+authorization)
    callback(authorization);
    */
  }
});

<Error>
	<Code>AccessDenied</Code>
	<Message>Access Denied.</Message>
	<Resource>gxtdlm-1258532084.cos.ap-beijing.myqcloud.com/wx114f04180b885f25.o6zAJs4_u9NmbTbvfTrLTVgRE9h0.6ZggaTp0lNhDd6c19a88e2e6d2a626487e7a487d78a5.jpeg</Resource>
	<RequestId>NWM4OWM4MGNfZGMyOTVkNjRfNDcyY18xOTU4YTFk</RequestId>
	<TraceId>OGVmYzZiMmQzYjA2OWNhODk0NTRkMTBiOWVmMDAxODc0OWRkZjk0ZDM1NmI1M2E2MTRlY2MzZDhmNmI5MWI1OTQyYWVlY2QwZTk2MDVmZDQ3MmI2Y2I4ZmI5ZmM4ODFjMTIyODZmMTQ1NWFiZTE0NGQ1ZDFiNmU5YWY4MmNkMzc=</TraceId>
</Error>