C# solves the problem of Baidu Map API APP SN verification failure (code example)

This article will introduce to you the solution to the SN verification failure problem encountered when using C# to call Baidu Map API. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

The signature (sn verification) problem encountered when using C# to call Baidu Map Web Service API is recorded here. ( Please ignore the IP whitelist verification )

1. First get ak and sk, these two things can be obtained from the console

2. At this address: sn signature algorithm, which provides java, php, c#, python2.7 Reference code

In the reference code provided by Baidu, there is a problem with the MD5 encryption method in the C# code. (When the author wrote the essay, there was still a problem with the code. I hope Baidu will officially fix this problem later)

Modify Baidu's MD5 method, the signature will be correct, and the API will be called normally, happy! !

Here is the complete signature code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web;

namespace IpService.Code
{
    public class BaiduAKSNCaculater
    {
        private static string MD5(string password)
        {
            try
            {
                System.Security.Cryptography.HashAlgorithm hash = System.Security.Cryptography.MD5.Create();
                byte[] hash_out = hash.ComputeHash(System.Text.Encoding.UTF8.GetBytes(password));

                var md5_str=BitConverter.ToString(hash_out).Replace("-", "");
                return md5_str.ToLower();

            }
            catch
            {
                
                throw;
            }
        }

        private static string UrlEncode(string str)
        {
            str = System.Web.HttpUtility.UrlEncode(str);
            byte[] buf = Encoding.ASCII.GetBytes(str);//等同于Encoding.ASCII.GetBytes(str)
            for (int i = 0; i < buf.Length; i++)
                if (buf[i] == &#39;%&#39;)
                {
                    if (buf[i + 1] >= &#39;a&#39;) buf[i + 1] -= 32;
                    if (buf[i + 2] >= &#39;a&#39;) buf[i + 2] -= 32;
                    i += 2;
                }
            return Encoding.ASCII.GetString(buf);//同上，等同于Encoding.ASCII.GetString(buf)
        }

        private static string HttpBuildQuery(IDictionary<string, string> querystring_arrays)
        {

            StringBuilder sb = new StringBuilder();
            foreach (var item in querystring_arrays)
            {
                sb.Append(UrlEncode(item.Key));
                sb.Append("=");
                sb.Append(UrlEncode(item.Value));
                sb.Append("&");
            }
            sb.Remove(sb.Length - 1, 1);
            return sb.ToString();
        }

        public static string CaculateAKSN(string ak, string sk, string url, IDictionary<string, string> querystring_arrays)
        {
            var queryString = HttpBuildQuery(querystring_arrays);

            var str = UrlEncode(url + "?" + queryString + sk);
           
            return MD5(str);
        }
    }
}

Here is the calling code

public static string GetIPAreas()
        {
            var ip = "你要查询的ip地址";
            var ak = "从百度控制台获取到应用AK";
            var sk = "从百度控制台获取到签名SK";
            var uri = "http://api.map.baidu.com";
            var path = "/location/ip";
            var param = new Dictionary<string, string>();
            param.Add("ip", ip);
            param.Add("ak", ak);

            //注意：签名的url参数，并非完整地址
            var sn = BaiduAKSNCaculater.CaculateAKSN(ak, sk, path, param);

            var url = string.Format("{0}{1}?ip={2}&ak={3}&sn={4}",
                uri,
                path,
                ip,
                ak,
                sn);

            var str = Code.HttpService.Get(url);
            return str;
        }

Written at the end, I hope Baidu officials will modify the code in the example as soon as possible so that others can use it Use

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