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。

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));    }}

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//调用：Url.UrlEncode(s);

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