IMAP郵件客戶端中讀取和創(chuàng)建郵件夾時需要對郵件夾名稱進行編碼和解碼。該方法是通過網(wǎng)絡上流傳的perl語言方法改寫的，配合InterIMAP項目可以編寫完整IMAP郵件客戶端。
InterIMAP項目地址： http://interimap.codeplex.com/
編碼和解碼方法，具體含義可以參考國際標準的定義：http://www.faqs.org/rfcs/rfc3501.html

C#：

//編碼

private string IMAPEncode(string folder)
{
    string rtn = "", base64;
    int index = 0;
    Regex regAsis = new Regex(@"\G(?:[\x20-\x25\x27-\x7e])+");
    Regex reg26 = new Regex(@"\G&");
    Regex regEncode = new Regex(@"\G(?:[^\x20-\x7e])+");
    Regex regEq = new Regex(@"=+$");
    Regex regSlash = new Regex(@"\/");
    while (index < folder.Length)
    {
        Match m;
        m = regAsis.Match(folder, index);
        if (m.Success)
        {
            index = index + m.Length;
            rtn = rtn + m.Value;
            continue;
        }
        m = reg26.Match(folder, index);
        if (m.Success)
        {
            index = index + m.Length;
            rtn = rtn + "&-";
            continue;
        }
        m = regEncode.Match(folder, index);
        if (m.Success)
        {
            index = index + m.Length;
            base64 = Convert.ToBase64String(Encoding.GetEncoding("UTF-16BE").GetBytes(m.Value));
            base64 = regEq.Replace(base64, "");
            base64 = regSlash.Replace(base64, ",");
            rtn = rtn + "&" + base64 + "-";
            continue;
        }
    }
    return rtn;
}
       
// 解碼
private string IMAPDeconde(string folder)
{
    string rtn = "", base64;
    int index = 0;
    Regex regAsis = new Regex(@"\G([^&]+)");
    Regex reg26 = new Regex(@"\G\&-");
    Regex regDecode = new Regex(@"\G\&([A-Za-z0-9+,]+)-?");
    Regex regComma = new Regex(@",");
    while (index < folder.Length)
    {
        Match m;
        m = regAsis.Match(folder, index);
        if(m.Success)
        {
            index = index + m.Length;
            rtn = rtn + m.Value;
            continue;
        }
        m = reg26.Match(folder, index);
        if(m.Success)
        { index = index + m.Length;
            rtn = rtn + "&";
            continue;
        }
        m = regDecode.Match(folder, index);
        if(m.Success)
        {
            index = index + m.Length;
            base64 = m.Value.Substring(1, m.Value.Length - 2);
            base64 = regComma.Replace(base64, "/");
            int mod = base64.Length % 4;
            if(mod > 0 )

            {

                int count = 4 - mod;
                while (count > 0)
                {
                    base64 += "=";
                    count--;
                }
                //base64 = base64.PadRight(base64.Length + (4 - mod), "=");

            }
            base64 = Encoding.GetEncoding("UTF-16BE").GetString(Convert.FromBase64String(base64));
            rtn = rtn + base64;
            continue;
        }
    }
    return rtn;
}

JAVA：

1. ImapFolderEncoder {  
2.     public static String encode(String folder) {  
3.     String rtn = "", base64;  
4.     int index = 0;  
5.     Pattern regAsis = Pattern.compile("\\G(?:[\\x20-\\x25\\x27-\\x7e])+");  
6.     Pattern reg26 = Pattern.compile("\\G&");  
7.     Pattern regEncode = Pattern.compile("\\G(?:[^\\x20-\\x7e])+");  
8.     Pattern regEq = Pattern.compile("=+$");  
9.     Pattern regSlash = Pattern.compile("\\/");  
10.     while (index < folder.length()) {  
11.         Matcher m;  
12.         m = regAsis.matcher(folder);  
13.         if (m.find(index)) {  
14.         index = index + (m.end() - m.start());  
15.         rtn = rtn + m.group();  
16.         continue;  
17.         }  
18.         m = reg26.matcher(folder);  
19.         if (m.find(index)) {  
20.         index = index + (m.end() - m.start());  
21.         rtn = rtn + "&-";  
22.         continue;  
23.         }  
24.         m = regEncode.matcher(folder);  
25.         if (m.find(index)) {  
26.         index = index + (m.end() - m.start());  
27.         base64 = SimpleUtil.encodeBase64Content(m.group(), "UTF-16BE");  
28.         base64 = base64.replaceAll(regEq.pattern(), "");  
29.         base64 = base64.replaceAll(regSlash.pattern(), ",");  
30.         rtn = rtn + "&" + base64 + "-";  
31.         continue;  
32.         }  
33.     }  
34.     return rtn;  
35.     }  
36.       
37. }