c#短信网关中关于短信内容编码的转换

无论在cmpp或sgip中，都会遇到短信编码格式转换的问题。
因为现在短信编码常用的格式有三种：0：ASCII串，8：UCS2编码，15：含GB汉字。在发送或接收短信时，都会用到相应的编码转换。如以下代码：
public static String Decode(Byte[] buf, int StartIndex, int Length, CODING Coding)
{
String str = String.Empty;
if (Coding == CODING.ASCII)
str = System.Text.Encoding.ASCII.GetString(buf, StartIndex, Length);
else if (Coding == CODING.UCS2)
str = System.Text.Encoding.BigEndianUnicode.GetString(buf, 0, Length);
else if (Coding == CODING.GBK)
str = System.Text.UnicodeEncoding.GetEncoding("gb2312").GetString(buf, StartIndex, Length);
return str;
}
public static Byte[] Encode(String str, CODING coding)
{
Byte[] buf = null;
if (str == null)
return buf;
if (coding == CODING.ASCII)
buf = System.Text.Encoding.ASCII.GetBytes(str);
else if (coding == CODING.UCS2)
buf = System.Text.Encoding.BigEndianUnicode.GetBytes(str);
else if (coding == CODING.GBK)
buf = System.Text.UnicodeEncoding.GetEncoding("gb2312").GetBytes(str);
return buf;
}
public static UInt32 CountLength(String str, CODING coding)
{
Byte[] buf = Encode(str, coding);
if (buf != null)
return (UInt32)buf.Length;
else
return 0;
}
在处理接收DELIVER时，也可以这样写
if (Msg_Fmt != 8)
{
if (Msg_Fmt != 15)
{
this.Msg_Content = System.Text.Encoding.ASCII.GetString(buffer, iPos, (int)this.Msg_Length);
}
else
{
this.Msg_Content = Syst