base64編碼，解碼

import sun.misc.BASE64Encoder;
import sun.misc.BASE64Decoder;
//編碼
String s = "Username";
BASE64Encoder encoder = new BASE64Encoder();
s = encoder.encode(s.getBytes("utf-8"));
syso(s);

//解碼
BASE64Decoder decoder = new BASE64Decoder();
byte[] bytes = decoder.decodeBuffer(s);
syso(new String(bytes,"utf-8"));