/***************************************************************** 軟件:Java簽名協議擴展 (Java Signature Protocol Extension, JSPE)* 版本:V1.0* 軟件功能:實現SSL簽名協議* 模塊:公共類Conversion*-----------------------------------------------------------------*  本模塊來自文獻[19]:Jamie Jaworski.Java Security Handbook.邱仲潘譯.電子工業出版社.2001年*                        版權歸Jamie Jaworski所有******************************************************************/package com.zsusoft.zfl;import java.util.*;// Provides static type/format conversion methods./******************************************************************************************  數組和字符串之間的轉換工具(Jamie Jaworski提供).******************************************************************************************/public class Conversion { private static String[] hexDigits = {"0","1","2","3","4","5","6","7",   "8","9","a","b","c","d","e","f"}; /** * Convert a byte to a hexadecimal String **/ public static String byteToHexString(byte b) {  int n = b;  if(n < 0) n = 256 + n;  int d1 = n / 16;  int d2 = n % 16;   return hexDigits[d1]+hexDigits[d2]; } /** * Convert a byte array to a hexadecimal String **/ public static String byteArrayToHexString(byte[] b) {  String result = "";  for(int i=0;i<b.length;++i)   result += byteToHexString(b[i]);   return result; } /** * Convert a byte array to a base 64 string (see RFC 1421) **/ public static String byteArrayToBase64String(byte[] b, int len) {  String s = "";  // Organize into three byte groups and convert  int n = len / 3;  int m = len % 3;  for(int i=0; i<n; ++i) {   int j = i*3;   s += toBase64(b[j],b[j+1],b[j+2]);  }  if(m == 1) s += toBase64(b[len-1]);  else if(m==2) s += toBase64(b[len-2],b[len-1]);  // Insert a new line every 64 characters  String result = "";  len = s.length();  n = len / 64;  m = len % 64;  for(int i=0; i<n; ++i) {   result += s.substring(i*64,(i+1)*64) + "\n";  }  if(m > 0) result += s.substring(n*64,len) + "\n";  return result; } /** * Convert a byte array to a base 64 string (see RFC 1421) **/ public static String byteArrayToBase64String(byte[] b) {  return byteArrayToBase64String(b,b.length); } /** * Perform the base64 transformation **/ private static String toBase64(byte b1, byte b2, byte b3) {  int[] digit = new int[4];  digit[0] = (b1 & 0xFC) >>> 2;  digit[1] = (b1 & 0x03) << 4;  digit[1] |= (b2 & 0xF0) >> 4;  digit[2] = (b2 & 0x0F) << 2;  digit[2] |= (b3 & 0xC0) >> 6;  digit[3] = (b3 & 0x3F);  String result = "";  for(int i=0;i<digit.length;++i)    result += base64Digit(digit[i]);  return result; } /** * Perform a padded base64 transformation **/ private static String toBase64(byte b1, byte b2) {  int[] digit = new int[3];  digit[0] = (b1 & 0xFC) >>> 2;  digit[1] = (b1 & 0x03) << 4;  digit[1] |= (b2 & 0xF0) >> 4;  digit[2] = (b2 & 0x0F) << 2;  String result = "";  for(int i=0;i<digit.length;++i)    result += base64Digit(digit[i]);  result += "=";  return result; } /** *   Perform a padded base64 transformation **/ private static String toBase64(byte b1) {  int[] digit = new int[2];  digit[0] = (b1 & 0xFC) >>> 2;  digit[1] = (b1 & 0x03) << 4;  String result = "";  for(int i=0;i<digit.length;++i)    result += base64Digit(digit[i]);  result += "==";  return result; } private static char base64Digit(int i) {  if(i<26) return (char) ('A' + i);  if(i<52) return (char) ('a' + (i - 26));  if(i<62) return (char) ('0' + (i - 52));  if(i == 62) return '+';  else return '/'; } /** *  Convert a base 64 string to a byte array (see RFC 1421) **/ public static byte[] base64StringToByteArray(String s)   throws NumberFormatException {  String t = "";  for(int i=0;i<s.length();++i) {   char c = s.charAt(i);   if(c == '\n') continue;   else if((c>='A' && c<='Z') || (c>='a' && c<='z') ||      (c>='0' && c<='9') || c=='+' || c=='/') t += c;   else if(c=='=') break;   else throw new NumberFormatException();  }  int len = t.length();  int n = 3*(len/4);  switch(len % 4) {  case 1:   throw new NumberFormatException();  case 2:   len += 2;   n += 1;   t += "==";   break;  case 3:   ++len;   n += 2;   t += "=";   break;  }  byte[] b = new byte[n];  for(int i=0; i < len/4; ++i) {   byte[] temp = base64ToBytes(t.substring(4*i,4*(i+1)));   for(int j=0;j<temp.length;++j) {    b[3*i+j] = temp[j];   }  }  return b; } private static byte[] base64ToBytes(String s) {  int len = 0;  for(int i=0;i<s.length();++i)   if(s.charAt(i) != '=') ++len;  int[] digit = new int[len];  for(int i=0;i<len;++i) {   char c = s.charAt(i);   if(c>='A' && c<='Z') digit[i] = c - 'A';   else if(c>='a' && c<='z') digit[i] = c - 'a' + 26;   else if(c>='0' && c<='9') digit[i] = c - '0' + 52;   else if(c=='+') digit[i] = 62;   else if(c=='/') digit[i] = 63;     }  byte[] b = new byte[len-1];  switch(len) {   case 4:    b[2] = (byte) ((((digit[2]) & 0x03) << 6) | digit[3]);   case 3:    b[1] = (byte) ((((digit[1]) & 0x0F) << 4) | ((digit[2] & 0x3C) >>> 2));   case 2:    b[0] = (byte) ((digit[0] << 2) | ((digit[1] & 0x30) >>> 4));  }  return b; }}