001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.tools;
003
004import java.nio.ByteBuffer;
005
006public final class Base64 {
007
008    private Base64() {
009        // Hide default constructor for utils classes
010    }
011    
012    private static String encDefault = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
013    private static String encUrlSafe = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
014
015    public static String encode(String s) {
016        return encode(s, false);
017    }
018
019    public static String encode(String s, boolean urlsafe) {
020        StringBuilder out = new StringBuilder();
021        String enc = urlsafe ? encUrlSafe : encDefault;
022        for (int i = 0; i < (s.length()+2)/3; ++i) {
023            int l = Math.min(3, s.length()-i*3);
024            String buf = s.substring(i*3, i*3+l);
025            out.append(enc.charAt(buf.charAt(0)>>2));
026            out.append(enc.charAt(
027                                  (buf.charAt(0) & 0x03) << 4 |
028                                  (l==1?
029                                   0:
030                                   (buf.charAt(1) & 0xf0) >> 4)));
031            out.append(l>1?enc.charAt((buf.charAt(1) & 0x0f) << 2 | (l==2?0:(buf.charAt(2) & 0xc0) >> 6)):'=');
032            out.append(l>2?enc.charAt(buf.charAt(2) & 0x3f):'=');
033        }
034        return out.toString();
035    }
036
037    public static String encode(ByteBuffer s) {
038        return encode(s, false);
039    }
040
041    public static String encode(ByteBuffer s, boolean urlsafe) {
042        StringBuilder out = new StringBuilder();
043        String enc = urlsafe ? encUrlSafe : encDefault;
044        // Read 3 bytes at a time.
045        for (int i = 0; i < (s.limit()+2)/3; ++i) {
046            int l = Math.min(3, s.limit()-i*3);
047            int byte0 = s.get() & 0xff;
048            int byte1 = l>1? s.get() & 0xff : 0;
049            int byte2 = l>2? s.get() & 0xff : 0;
050
051            out.append(enc.charAt(byte0>>2));
052            out.append(enc.charAt(
053                                  (byte0 & 0x03) << 4 |
054                                  (l==1?
055                                   0:
056                                   (byte1 & 0xf0) >> 4)));
057            out.append(l>1?enc.charAt((byte1 & 0x0f) << 2 | (l==2?0:(byte2 & 0xc0) >> 6)):'=');
058            out.append(l>2?enc.charAt(byte2 & 0x3f):'=');
059        }
060        return out.toString();
061    }
062}