今天用BASE64加密时遇到一个奇怪问题，每76个字符自动换行，在网上找到了重写方法：

public class BASE64Encoder
{private static char[] codec_table = { 'A', 'B', 'C', 'D', 'E', 'F', 'G',  'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',  'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g',  'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',  'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6',  '7', '8', '9', '+', '/' };  public BASE64Encoder() {  }  public static String encode(byte[] a) {  int totalBits = a.length * 8;  int nn = totalBits % 6;  int curPos = 0;// process bits  StringBuffer toReturn = new StringBuffer();  while (curPos < totalBits) {  int bytePos = curPos / 8;  switch (curPos % 8) {  case 0:  toReturn.append(codec_table[(a[bytePos] & 0xfc) >> 2]);  break;  case 2:  toReturn.append(codec_table[(a[bytePos] & 0x3f)]);  break;  case 4:  if (bytePos == a.length - 1) {  toReturn  .append(codec_table[((a[bytePos] & 0x0f) << 2) & 0x3f]);  } else {  int pos = (((a[bytePos] & 0x0f) << 2) | ((a[bytePos + 1] & 0xc0) >> 6)) & 0x3f;  toReturn.append(codec_table[pos]);  }  break;  case 6:  if (bytePos == a.length - 1) {  toReturn  .append(codec_table[((a[bytePos] & 0x03) << 4) & 0x3f]);  } else {  int pos = (((a[bytePos] & 0x03) << 4) | ((a[bytePos + 1] & 0xf0) >> 4)) & 0x3f;  toReturn.append(codec_table[pos]);  }  break;  default:  //never hanppen  break;  }  curPos+=6;  }  if(nn==2)  {  toReturn.append("==");  }  else if(nn==4)  {  toReturn.append("=");  }  return toReturn.toString();  }  }  

byte 转String str.getBytes();

String 转 byte new String(byte);