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@xixilive
Created May 4, 2012 15:00
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Base32 string encoder developing with C#
using System;
using System.Collections.Generic;
using System.Text;
namespace Mickey.Utils
{
/// <summary>
/// 字符串编码/解码
/// </summary>
public static class StringEncoder
{
internal const string CODE_CHARS = "12345678abcdefghijklmnpqrstuvwxy";
internal const byte BIT5 = 0x5;
internal const byte BIT8 = 0x8;
private static char[] char_table;
/// <summary>
/// 使用指定的字符集对给定的字符串编码,默认忽略待编码字符串的大小写
/// </summary>
/// <param name="str">待编码字符串</param>
/// <param name="encoding">指定编码</param>
/// <returns>string</returns>
public static string Encode(string str, Encoding encoding)
{
return Encode(str, encoding, true);
}
/// <summary>
/// 使用UTF8字符集对给定的字符串编码
/// </summary>
/// <param name="str">待编码字符串</param>
/// <param name="ignoreCase">指定是否忽略大小写</param>
/// <returns>string</returns>
public static string Encode(string str, bool ignoreCase)
{
return Encode(str, Encoding.UTF8, true);
}
/// <summary>
/// 使用UTF8字符集对给定的字符串编码,默认忽略待编码字符串的大小写
/// </summary>
/// <param name="str">待编码字符串</param>
/// <returns>string</returns>
public static string Encode(string str)
{
return Encode(str, Encoding.UTF8, true);
}
/// <summary>
/// 对已编码的字符串进行解码,默认UTF8字符集
/// </summary>
/// <param name="str">待解码字符串</param>
/// <returns>string</returns>
public static string Decode(string str)
{
return Decode(str, Encoding.UTF8);
}
/// <summary>
/// 使用指定的字符集对给定的字符串编码,并可指定是否忽略待编码字符串的大小写
/// </summary>
/// <param name="str">待编码字符串</param>
/// <param name="encoding">指定编码</param>
/// <param name="ignoreCase">指定是否忽略大小写</param>
/// <returns>string</returns>
public static string Encode(string str, Encoding encoding, bool ignoreCase)
{
if (String.IsNullOrEmpty(str))
{
return "";
}
if (ignoreCase)
{
str = str.ToLower();
}
StringBuilder binaryString = new StringBuilder();
byte[] strBytes = encoding.GetBytes(str);
foreach (byte b in strBytes)
{
binaryString.Append(Convert.ToString(b, 2).PadLeft(8, '0'));
}
int blocks = binaryString.Length % BIT5 == 0 ? binaryString.Length / BIT5 : binaryString.Length / BIT5 + 1;
string[] bit5Array = new string[blocks];
int readSize = 0;
for (int i = 0; i < blocks; i++)
{
readSize = BIT5;
if (i * BIT5 + BIT5 > binaryString.Length)
{
readSize = binaryString.Length - i * BIT5;
}
bit5Array[i] = binaryString.ToString(i * BIT5, readSize);
bit5Array[i] = bit5Array[i].PadRight(BIT5, '0');
bit5Array[i] = bit5Array[i].PadLeft(BIT8, '0');
}
byte[] encodedBytes = new byte[bit5Array.Length];
for (int i = 0; i < bit5Array.Length; i++)
{
encodedBytes[i] = Convert.ToByte(bit5Array[i], 2);
}
if (char_table == null)
{
char_table = CODE_CHARS.ToCharArray();
}
StringBuilder encodedString = new StringBuilder();
foreach (byte b in encodedBytes)
{
encodedString.Append(char_table[b]);
}
return encodedString.ToString();
}
/// <summary>
/// 对已编码的字符串进行解码
/// </summary>
/// <param name="str">待解码字符串</param>
/// <param name="encoding">编码时使用的编码</param>
/// <returns>string</returns>
public static string Decode(string str, Encoding encoding)
{
if (String.IsNullOrEmpty(str))
{
return "";
}
str = str.ToLower();
StringBuilder binaryString = new StringBuilder();
foreach (char c in str.ToCharArray())
{
binaryString.Append(Convert.ToString(CODE_CHARS.IndexOf(c), 2).PadLeft(BIT8, '0'));
}
int n = binaryString.Length / BIT8;
string[] bit8Array = new string[n];
for (int i = 0; i < n; i++)
{
bit8Array[i] = binaryString.ToString(i * BIT8, BIT8).Substring(BIT8 - BIT5);
}
string bit8String = String.Join("", bit8Array);
bit8Array = new string[bit8String.Length / BIT8];
for (int i = 0; i < bit8Array.Length; i++)
{
bit8Array[i] = bit8String.Substring(i * BIT8, BIT8);
}
byte[] decodedBytes = new byte[bit8Array.Length];
for (int i = 0; i < decodedBytes.Length; i++)
{
decodedBytes[i] = Convert.ToByte(bit8Array[i], 2);
}
return encoding.GetString(decodedBytes);
}
}
}
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