001// License: GPL. For details, see LICENSE file. 002package org.openstreetmap.josm.tools; 003 004import java.nio.ByteBuffer; 005 006/** 007 * This class implements an encoder for encoding byte and character data using the 008 * <a href="https://en.wikipedia.org/wiki/Base64">Base64</a> encoding scheme as specified in 009 * <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a> ("base64", default) and 010 * <a href="http://tools.ietf.org/html/rfc4648#section-4">RFC 4648</a> ("base64url"). 011 * @since 195 012 */ 013public final class Base64 { 014 // TODO: Remove this class when switching to Java 8 (finally integrated in Java SE as java.util.Base64.Encoder) 015 016 private Base64() { 017 // Hide default constructor for utils classes 018 } 019 020 /** "base64": RFC 2045 default encoding */ 021 private static String encDefault = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 022 /** "base64url": RFC 4648 url-safe encoding */ 023 private static String encUrlSafe = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; 024 025 /** 026 * Encodes all characters from the specified string into a new String using the Base64 default encoding scheme. 027 * @param s the string to encode 028 * @return A new string containing the resulting encoded characters. 029 */ 030 public static String encode(String s) { 031 return encode(s, false); 032 } 033 034 /** 035 * Encodes all characters from the specified string into a new String using a supported Base64 encoding scheme. 036 * @param s the string to encode 037 * @param urlsafe if {@code true}, uses "base64url" encoding, otherwise use the "base64" default encoding 038 * @return A new string containing the resulting encoded characters. 039 * @since 3840 040 */ 041 public static String encode(String s, boolean urlsafe) { 042 StringBuilder out = new StringBuilder(); 043 String enc = urlsafe ? encUrlSafe : encDefault; 044 for (int i = 0; i < (s.length()+2)/3; ++i) { 045 int l = Math.min(3, s.length()-i*3); 046 String buf = s.substring(i*3, i*3+l); 047 out.append(enc.charAt(buf.charAt(0)>>2)); 048 out.append(enc.charAt( 049 (buf.charAt(0) & 0x03) << 4 | 050 (l==1? 051 0: 052 (buf.charAt(1) & 0xf0) >> 4))); 053 out.append(l>1?enc.charAt((buf.charAt(1) & 0x0f) << 2 | (l==2?0:(buf.charAt(2) & 0xc0) >> 6)):'='); 054 out.append(l>2?enc.charAt(buf.charAt(2) & 0x3f):'='); 055 } 056 return out.toString(); 057 } 058 059 /** 060 * Encodes all remaining bytes from the specified byte buffer into a new string using the Base64 default encoding scheme. 061 * Upon return, the source buffer's position will be updated to its limit; its limit will not have been changed. 062 * @param s the source ByteBuffer to encode 063 * @return A new string containing the resulting encoded characters. 064 */ 065 public static String encode(ByteBuffer s) { 066 return encode(s, false); 067 } 068 069 /** 070 * Encodes all remaining bytes from the specified byte buffer into a new string using a supported Base64 encoding scheme. 071 * Upon return, the source buffer's position will be updated to its limit; its limit will not have been changed. 072 * @param s the source ByteBuffer to encode 073 * @param urlsafe if {@code true}, uses "base64url" encoding, otherwise use the "base64" default encoding 074 * @return A new string containing the resulting encoded characters. 075 * @since 3840 076 */ 077 public static String encode(ByteBuffer s, boolean urlsafe) { 078 StringBuilder out = new StringBuilder(); 079 String enc = urlsafe ? encUrlSafe : encDefault; 080 // Read 3 bytes at a time. 081 for (int i = 0; i < (s.limit()+2)/3; ++i) { 082 int l = Math.min(3, s.limit()-i*3); 083 int byte0 = s.get() & 0xff; 084 int byte1 = l>1? s.get() & 0xff : 0; 085 int byte2 = l>2? s.get() & 0xff : 0; 086 087 out.append(enc.charAt(byte0>>2)); 088 out.append(enc.charAt( 089 (byte0 & 0x03) << 4 | 090 (l==1? 091 0: 092 (byte1 & 0xf0) >> 4))); 093 out.append(l>1?enc.charAt((byte1 & 0x0f) << 2 | (l==2?0:(byte2 & 0xc0) >> 6)):'='); 094 out.append(l>2?enc.charAt(byte2 & 0x3f):'='); 095 } 096 return out.toString(); 097 } 098}