iot/projects/Infrastructure/Extensions/StringExtensions.cs

using HtmlAgilityPack;
using System;
using System.Linq;
using System.Security.Cryptography;
using System.Text;

namespace Infrastructure.Extensions
{
    public static class StringExtensions
    {
        public static string Format(this string value, params object[] args)
        {
            return string.Format(value, args);
        }

        public static string GetExtension(this string filename)
        {
            return filename.Substring(filename.LastIndexOf('.') + 1).ToLower();
        }

        public static string GetSummary(this string value, int length = 32)
        {
            if (string.IsNullOrWhiteSpace(value))
            {
                return value;
            }
            if (value.Length > length)
            {
                return value.Substring(0, length) + "...";
            }
            return value;
        }

        public static string HtmlToText(this string html, int length = 10)
        {
            if (string.IsNullOrWhiteSpace(html))
            {
                return html;
            }
            var result = string.Empty;
            var doc = new HtmlDocument();
            doc.LoadHtml(html);
            var builder = new StringBuilder();
            builder.Append(result);
            foreach (var item in doc.DocumentNode.ChildNodes)
            {
                builder.Append(item.InnerText);
                if (result.Length >= length)
                {
                    result = result.Substring(0, length);
                    break;
                }
            }
            result = builder.ToString();
            return result;
        }

        public static byte[] StringToByteArray(this string hex)
        {
            return Enumerable.Range(0, hex.Length / 2).Select(x => Convert.ToByte(hex.Substring(x * 2, 2), 16)).ToArray();
        }

        public static string DESEncrypt(this string value, string key)
        {
            using (var des = new DESCryptoServiceProvider())
            {
                var inputByteArray = Encoding.Default.GetBytes(value);
                var md5Key = key.Md5().Substring(0, 8);
                des.Key = ASCIIEncoding.ASCII.GetBytes(md5Key);
                des.IV = ASCIIEncoding.ASCII.GetBytes(md5Key);
                using (var ms = new System.IO.MemoryStream())
                {
                    using (var cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(inputByteArray, 0, inputByteArray.Length);
                        cs.FlushFinalBlock();
                        var ret = new StringBuilder();
                        foreach (var item in ms.ToArray())
                        {
                            ret.AppendFormat("{0:X2}", item);
                        }
                        return ret.ToString();
                    }
                }
            }
        }

        public static string DESDecrypt(this string value, string key)
        {
            using (var des = new DESCryptoServiceProvider())
            {
                var len = value.Length / 2;
                byte[] inputByteArray = new byte[len];
                for (int i = 0; i < len; i++)
                {
                    inputByteArray[i] = (byte)Convert.ToInt32(value.Substring(i * 2, 2), 16);
                }
                var md5Key = key.Md5().Substring(0, 8);
                des.Key = ASCIIEncoding.ASCII.GetBytes(md5Key);
                des.IV = ASCIIEncoding.ASCII.GetBytes(md5Key);
                using (var ms = new System.IO.MemoryStream())
                {
                    CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
                    cs.Write(inputByteArray, 0, inputByteArray.Length);
                    cs.FlushFinalBlock();
                    return Encoding.Default.GetString(ms.ToArray());
                }
            }
        }
    }
}