阿里云增值税发票识别NET Rest API调用示例

using System.Globalization;
using System.Net;
using System.Net.Http.Headers;
using System.Security.Cryptography;
using System.Text;
using System.Web;
using Newtonsoft.Json;

namespace SignatureDemo
{
    public class Request
    {
        public string HttpMethod { get; private set; }
        public string CanonicalUri { get; private set; }
        public string Host { get; private set; }
        public string XAcsAction { get; private set; }
        public string XAcsVersion { get; private set; }
        public SortedDictionary<string, object> Headers { get; private set; }
        public byte[] Body { get; set; }
        public Dictionary<string, object> QueryParam { get; set; }

        public Request(string httpMethod, string canonicalUri, string host, string xAcsAction, string xAcsVersion)
        {
            HttpMethod = httpMethod;
            CanonicalUri = canonicalUri;
            Host = host;
            XAcsAction = xAcsAction;
            XAcsVersion = xAcsVersion;
            Headers = [];
            QueryParam = [];
            Body = null;
            InitHeader();
        }

        private void InitHeader()
        {
            Headers["host"] = Host;
            Headers["x-acs-action"] = XAcsAction;
            Headers["x-acs-version"] = XAcsVersion;
            DateTime utcNow = DateTime.UtcNow;
            Headers["x-acs-date"] = utcNow.ToString("yyyy-MM-dd'T'HH:mm:ss'Z'", CultureInfo.InvariantCulture);
            Headers["x-acs-signature-nonce"] = Guid.NewGuid().ToString();
        }
    }

    public class Program
    {
        private static readonly string AccessKeyId = "《AccessKey》";
        private static readonly string AccessKeySecret = "《AccessSecret》";

        private const string Algorithm = "ACS3-HMAC-SHA256";
        private const string ContentType = "content-type";

        /**
        * 签名示例，您需要根据实际情况替换main方法中的示例参数。
        * ROA接口和RPC接口只有canonicalUri取值逻辑是完全不同，其余内容都是相似的。
        *
        * 通过API元数据获取请求方法（methods）、请求参数名称（name）、请求参数类型（type）、请求参数位置（in），并将参数封装到SignatureRequest中。
        * 1. 请求参数在元数据中显示"in":"query"，通过queryParam传参。
        * 2. 请求参数在元数据中显示"in": "body"，通过body传参。
        * 3. 请求参数在元数据中显示"in": "formData"，通过body传参。
        */
        public static void Main(string[] args)
        {
            // RPC接口请求示例一：请求参数"in":"query"
            string httpMethod = "POST"; // 请求方式，大部分RPC接口同时支持POST和GET，此处以POST为例
            string canonicalUri = "/"; // RPC接口无资源路径，故使用正斜杠（/）作为CanonicalURI
            string host = "ocr.cn-shanghai.aliyuncs.com"; // 云产品服务接入点
            string xAcsAction = "RecognizeVATInvoice"; // API名称
            string xAcsVersion = "2019-12-30"; // API版本号
            var request = new Request(httpMethod, canonicalUri, host, xAcsAction, xAcsVersion);
            // DescribeInstanceStatus请求参数如下：
            // RegionId在元数据中显示的类型是String，"in":"query"，必填
            request.QueryParam["RegionId"] = "cn-shanghai";
            request.QueryParam["FileURL"] = "http://viapi-test.oss-cn-shanghai.aliyuncs.com/viapi-3.0domepic/ocr/RecognizeVATInvoice/RecognizeVATInvoice3.jpg";
            request.QueryParam["FileType"] = "jpg";

            GetAuthorization(request);
            // 调用API
            var result = CallApiAsync(request);
            Console.WriteLine($"result:{result.Result}");
        }

        private static async Task<string?> CallApiAsync(Request request)
        {
            try
            {
                // 声明 httpClient
                using var httpClient = new HttpClient();

                // 构建 URL
                string url = $"https://{request.Host}{request.CanonicalUri}";
                var uriBuilder = new UriBuilder(url);
                var query = new List<string>();

                // 添加请求参数
                foreach (var entry in request.QueryParam.OrderBy(e => e.Key.ToLower()))
                {
                    string value = entry.Value?.ToString() ?? "";
                    query.Add($"{entry.Key}={Uri.EscapeDataString(value)}");
                }

                uriBuilder.Query = string.Join("&", query);
                Console.WriteLine(uriBuilder.Uri);
                var requestMessage = new HttpRequestMessage
                {
                    Method = new HttpMethod(request.HttpMethod),
                    RequestUri = uriBuilder.Uri,
                };

                // 设置请求头
                foreach (var entry in request.Headers)
                {
                    if (entry.Key == "Authorization")
                    {
                        requestMessage.Headers.TryAddWithoutValidation("Authorization", entry.Value.ToString()); ;
                    }
                    else if (entry.Key == ContentType) // 与main中定义的要一致
                    {
                        continue;
                    }
                    else
                    {
                        requestMessage.Headers.Add(entry.Key, entry.Value.ToString());
                    }
                }

                if (request.Body != null)
                {
                    HttpContent content = new ByteArrayContent(request.Body);
                    string contentType = request.Headers["content-type"].ToString();
                    content.Headers.ContentType = MediaTypeHeaderValue.Parse(contentType);
                    requestMessage.Content = content;
                }

                // 发送请求
                HttpResponseMessage response = await httpClient.SendAsync(requestMessage);
                // 读取响应内容
                string result = await response.Content.ReadAsStringAsync();
                return result;
            }
            catch (UriFormatException e)
            {
                Console.WriteLine("Invalid URI syntax");
                Console.WriteLine(e.Message);
                return null;
            }
            catch (Exception e)
            {
                Console.WriteLine("Failed to send request");
                Console.WriteLine(e);
                return null;
            }
        }

        private static void GetAuthorization(Request request)
        {
            try
            {
                // 处理queryParam中参数值为List、Map类型的参数，将参数平铺
                request.QueryParam = FlattenDictionary(request.QueryParam);

                // 步骤 1：拼接规范请求串
                StringBuilder canonicalQueryString = new();
                foreach (var entry in request.QueryParam.OrderBy(e => e.Key.ToLower()))
                {
                    if (canonicalQueryString.Length > 0)
                    {
                        canonicalQueryString.Append('&');
                    }
                    canonicalQueryString.Append($"{PercentCode(entry.Key)}={PercentCode(entry.Value?.ToString() ?? "")}");
                }

                byte[] requestPayload = request.Body == null ? Encoding.UTF8.GetBytes("") : request.Body;
                string hashedRequestPayload = Sha256Hash(requestPayload);
                request.Headers["x-acs-content-sha256"] = hashedRequestPayload;

                StringBuilder canonicalHeaders = new();
                StringBuilder signedHeadersSb = new();
                foreach (var entry in request.Headers.OrderBy(e => e.Key.ToLower()))
                {
                    if (entry.Key.StartsWith("x-acs-", StringComparison.CurrentCultureIgnoreCase) || entry.Key.Equals("host", StringComparison.OrdinalIgnoreCase) || entry.Key.Equals(ContentType, StringComparison.OrdinalIgnoreCase))
                    {
                        string lowerKey = entry.Key.ToLower();
                        string value = (entry.Value?.ToString() ?? "").Trim();
                        canonicalHeaders.Append($"{lowerKey}:{value}\n");
                        signedHeadersSb.Append($"{lowerKey};");
                    }
                }
                string signedHeaders = signedHeadersSb.ToString().TrimEnd(';');
                string canonicalRequest = $"{request.HttpMethod}\n{request.CanonicalUri}\n{canonicalQueryString}\n{canonicalHeaders}\n{signedHeaders}\n{hashedRequestPayload}";
                Console.WriteLine($"canonicalRequest:{canonicalRequest}");

                // 步骤 2：拼接待签名字符串
                string hashedCanonicalRequest = Sha256Hash(Encoding.UTF8.GetBytes(canonicalRequest));
                string stringToSign = $"{Algorithm}\n{hashedCanonicalRequest}";
                Console.WriteLine($"stringToSign:{stringToSign}");

                // 步骤 3：计算签名
                string signature = HmacSha256(AccessKeySecret, stringToSign);

                // 步骤 4：拼接 Authorization
                string authorization = $"{Algorithm} Credential={AccessKeyId},SignedHeaders={signedHeaders},Signature={signature}";
                request.Headers["Authorization"] = authorization;
                Console.WriteLine($"authorization:{authorization}");
            }
            catch (Exception ex)
            {
                Console.WriteLine("Failed to get authorization");
                Console.WriteLine(ex.Message);
            }
        }

        private static string FormDataToString(Dictionary<string, object> formData)
        {
            Dictionary<string, object> tileMap = FlattenDictionary(formData);

            StringBuilder result = new StringBuilder();
            bool first = true;
            string symbol = "&";

            foreach (var entry in tileMap)
            {
                string value = entry.Value.ToString();
                if (!string.IsNullOrEmpty(value))
                {
                    if (!first)
                    {
                        result.Append(symbol);
                    }
                    first = false;
                    result.Append(PercentCode(entry.Key));
                    result.Append("=");
                    result.Append(PercentCode(value));
                }
            }
            return result.ToString();
        }

        private static Dictionary<string, object> FlattenDictionary(Dictionary<string, object> dictionary, string prefix = "")
        {
            var result = new Dictionary<string, object>();
            foreach (var kvp in dictionary)
            {
                string key = string.IsNullOrEmpty(prefix) ? kvp.Key : $"{prefix}.{kvp.Key}";

                if (kvp.Value is Dictionary<string, object> nestedDict)
                {
                    var nestedResult = FlattenDictionary(nestedDict, key);
                    foreach (var nestedKvp in nestedResult)
                    {
                        result[nestedKvp.Key] = nestedKvp.Value;
                    }
                }
                else if (kvp.Value is List<string> list)
                {
                    for (int i = 0; i < list.Count; i++)
                    {
                        result[$"{key}.{i + 1}"] = list[i];
                    }
                }
                else
                {
                    result[key] = kvp.Value;
                }
            }
            return result;
        }

        private static string HmacSha256(string key, string message)
        {
            using (var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(key)))
            {
                byte[] hashMessage = hmac.ComputeHash(Encoding.UTF8.GetBytes(message));
                return BitConverter.ToString(hashMessage).Replace("-", "").ToLower();
            }
        }

        private static string Sha256Hash(byte[] input)
        {
            byte[] hashBytes = SHA256.HashData(input);
            return BitConverter.ToString(hashBytes).Replace("-", "").ToLower();
        }

        private static string PercentCode(string str)
        {
            if (string.IsNullOrEmpty(str))
            {
                throw new ArgumentException("输入字符串不可为null或空");
            }
            return Uri.EscapeDataString(str).Replace("+", "%20").Replace("*", "%2A").Replace("%7E", "~");
        }
    }
}