把utf8的string轉化為base64的string：
public string base64encode(string data)
{
try
byte[] encdata_byte = new byte[data.length];
encdata_byte = system.text.encoding.utf8.getbytes(data);
string encodeddata = convert.tobase64string(encdata_byte);
return encodeddata;
}
catch(exception e)
throw new exception("error in base64encode" + e.message);
把base64的string轉化為utf8的string：
public string base64decode(string data)
system.text.utf8encoding encoder = new system.text.utf8encoding();
system.text.decoder utf8decode = encoder.getdecoder();
byte[] todecode_byte = convert.frombase64string(data);
int charcount = utf8decode.getcharcount(todecode_byte, 0, todecode_byte.length);
char[] decoded_char = new char[charcount];
utf8decode.getchars(todecode_byte, 0, todecode_byte.length, decoded_char, 0);
string result = new string(decoded_char);
return result;
throw new exception("error in base64decode" + e.message);
最主要的是使用system.convert