C# UrlEncoding

一个类来编码URL ，.net 自带的 HttpUtility.UrlEncode， Uri.EscapeUriString 都不能满足超长度的字符串编码，根据官方文档知道 stringToEscape 的长度超过 32766 个字符。https://msdn.microsoft.com/zh-cn/library/system.uri.escapeuristring(v=vs.110).aspx

于是用下面这个类就好了：

public static class Url
{
    private static bool IsSafe(char ch)
    {
        if ((((ch >= 'a') && (ch <= 'z')) || ((ch >= 'A') && (ch <= 'Z'))) || ((ch >= '0') && (ch <= '9')))
        {
            return true;
        }
        switch (ch)
        {
            case '\'':
            case '(':
            case ')':
            case '*':
            case '-':
            case '.':
            case '_':
            case '!':
                return true;
        }
        return false;

    }

    private static char IntToHex(int n)
    {
        if (n <= 9)
        {
            return (char)(n + 0x30);
        }
        return (char)((n - 10) + 0x61);
    }

    public static byte[] UrlEncodeBytesToBytes(byte[] bytes, int offset, int count, bool alwaysCreateReturnValue)
    {
        int num = 0;
        int num2 = 0;
        for (int i = 0; i < count; i++)
        {
            char ch = (char)bytes[offset + i];
            if (ch == ' ')
            {
                num++;
            }
            else if (!IsSafe(ch))
            {
                num2++;
            }
        }
        if ((!alwaysCreateReturnValue && (num == 0)) && (num2 == 0))
        {
            return bytes;
        }
        byte[] buffer = new byte[count + (num2 * 2)];
        int num4 = 0;
        for (int j = 0; j < count; j++)
        {
            byte num6 = bytes[offset + j];
            char ch2 = (char)num6;
            if (IsSafe(ch2))
            {
                buffer[num4++] = num6;
            }
            else if (ch2 == ' ')
            {
                buffer[num4++] = 0x2b;
            }
            else
            {
                buffer[num4++] = 0x25;
                buffer[num4++] = (byte)IntToHex((num6 >> 4) & 15);
                buffer[num4++] = (byte)IntToHex(num6 & 15);
            }
        }
        return buffer;
    }

    public static byte[] UrlEncodeToBytes(string str)
    {
        if (str == null)
        {
            return null;
        }
        return UrlEncodeToBytes(str, Encoding.UTF8);
    }

    public static byte[] UrlEncodeToBytes(string str, Encoding e)
    {
        if (str == null)
        {
            return null;
        }
        byte[] bytes = e.GetBytes(str);
        return UrlEncodeToBytes(bytes);
    }

    public static byte[] UrlEncodeToBytes(byte[] bytes)
    {
        if (bytes == null)
        {
            return null;
        }
        return UrlEncodeBytesToBytes(bytes, 0, bytes.Length, false);
    }

    public static string UrlEncode(string str, Encoding e)
    {
        if (str == null)
        {
            return null;
        }
        return Encoding.ASCII.GetString(UrlEncodeToBytes(str, e));
    }

    public static string UrlEncode(string str)
    {
        if (str == null)
        {
            return null;
        }
        return UrlEncode(str, Encoding.UTF8);
    }

    public static string UrlEncode(byte[] bytes)
    {
        if (bytes == null)
        {
            return null;
        }
        return Encoding.ASCII.GetString(UrlEncodeToBytes(bytes));
    }
}

//-----------------------------------------------------------
//调用：Url.UrlEncode(s);
//---------------------------------------------------------