File	Doc	Category	Size	Date	Package
Base64.java	API Doc	J2ME MIDP 2.0	5377	Thu Nov 07 12:02:38 GMT 2002	com.sun.midp.jadtool

Base64

• java.lang.Object

Fields Summary

Constructors Summary

Methods Summary
public static byte[]	decode(java.lang.String base64) decode convert a base64 string into an array of bytes. param base64 A String of base64 digits to decode. return A byte array containing the decoded value of the base64 input string // how many padding digits? int pad = 0; for (int i = base64.length() - 1; base64.charAt(i) == '="; i--) pad++; // we know know the lenght of the target byte array. int length = base64.length() * 6 / 8 - pad; byte[] raw = new byte[length]; int rawIndex = 0; // loop through the base64 value. A correctly formed // base64 string always has a multiple of 4 characters. for (int i = 0; i < base64.length(); i += 4) { int block = (getValue(base64.charAt(i)) << 18) + (getValue(base64.charAt(i + 1)) << 12) + (getValue(base64.charAt(i + 2)) << 6) + (getValue(base64.charAt(i + 3))); // based on the block, the byte array is filled with the // appropriate 8 bit values for (int j = 0; j < 3 && rawIndex + j < raw.length; j++) raw[rawIndex + j] = (byte)((block >> (8 * (2 - j))) & 0xff); rawIndex += 3; } return raw;
public static java.lang.String	encode(byte[] raw) encode coverts a byte array to a string populated with base64 digits. It steps through the byte array calling a helper methode for each block of three input bytes param raw The byte array to encode return A string in base64 encoding StringBuffer encoded = new StringBuffer(); for (int i = 0; i < raw.length; i += 3) { encoded.append(encodeBlock(raw, i)); } return encoded.toString();
protected static char[]	encodeBlock(byte[] raw, int offset) int block = 0; // how much space left in input byte array int slack = raw.length - offset - 1; // if there are fewer than 3 bytes in this block, calculate end int end = (slack >= 2) ? 2 : slack; // convert signed quantities into unsigned for (int i = 0; i <= end; i++) { byte b = raw[offset + i]; int neuter = (b < 0) ? b + 256 : b; block += neuter << (8 * (2 - i)); } // extract the base64 digets, which are six bit quantities. char[] base64 = new char[4]; for (int i = 0; i < 4; i++) { int sixbit = (block >>> (6 * (3 - i))) & 0x3f; base64[i] = getChar(sixbit); } // pad return block if needed if (slack < 1) base64[2] = '="; if (slack < 2) base64[3] = '="; // always returns an array of 4 characters return base64;
protected static char	getChar(int sixBit) if (sixBit >= 0 && sixBit <= 25) return (char)('A" + sixBit); if (sixBit >= 26 && sixBit <= 51) return (char)('a" + (sixBit - 26)); if (sixBit >= 52 && sixBit <= 61) return (char)('0" + (sixBit - 52)); if (sixBit == 62) return '+"; if (sixBit == 63) return '/"; return '?";
protected static int	getValue(char c) if (c >= 'A" && c <= 'Z") return c - 'A"; if (c >= 'a" && c <= 'z") return c - 'a" + 26; if (c >= '0" && c <= '9") return c - '0" + 52; if (c == '+") return 62; if (c == '/") return 63; if (c == '=") return 0; return -1;