Encode/Decode to/from Base64
From CodeCodex
[edit] Implementations
[edit] Java
As seen in this HowTo, the sun.misc.BASE64Encoder/Decoder or creating your own Base64 handling are the more common way to deal with Base64 encoding/decoding. Here some alternatives which are maybe easier (and safer) to use.
Using javax.mail.internet.MimeUtility
import javax.mail.internet.MimeUtility;
import java.io.*;
public class Base64Utils {
public static byte[] encode(byte[] b) throws Exception {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
OutputStream b64os = MimeUtility.encode(baos, "base64");
b64os.write(b);
b64os.close();
return baos.toByteArray();
}
public static byte[] decode(byte[] b) throws Exception {
ByteArrayInputStream bais = new ByteArrayInputStream(b);
InputStream b64is = MimeUtility.decode(bais, "base64");
byte[] tmp = new byte[b.length];
int n = b64is.read(tmp);
byte[] res = new byte[n];
System.arraycopy(tmp, 0, res, 0, n);
return res;
}
public static void main(String[] args) throws Exception {
String test = "realhowto";
byte res1[] = Base64Utils.encode(test.getBytes());
System.out.println(test + " base64 -> " + java.util.Arrays.toString(res1));
System.out.println(new String(res1));
byte res2[] = Base64Utils.decode(res1);
System.out.println("");
System.out.println( java.util.Arrays.toString(res1) + " string --> "
+ new String(res2));
/*
* output
* realhowto base64 ->
* [99, 109, 86, 104, 98, 71, 104, 118, 100, 51, 82, 118]
* cmVhbGhvd3Rv
* [99, 109, 86, 104, 98, 71, 104, 118, 100, 51, 82, 118]
* string --> realhowto
*/
}
}
Using Apache Commons Codec Apache Commons Codec provides implementations of common encoders and decoders such as Base64, Hex, Phonetic and URLs. Download at http://commons.apache.org/codec/
import org.apache.commons.codec.binary.Base64;
public class Codec {
public static void main(String[] args) {
try {
String clearText = "Hello world";
String encodedText;
// Base64
encodedText = new String(Base64.encodeBase64(clearText.getBytes()));
System.out.println("Encoded: " + encodedText);
System.out.println("Decoded:"
+ new String(Base64.decodeBase64(encodedText.getBytes())));
//
// output :
// Encoded: SGVsbG8gd29ybGQ=
// Decoded:Hello world
//
}
catch (Exception e) {
e.printStackTrace();
}
}
}
MiGBase64
MiGBase64 is a very fast Base64 Codec written in Java. http://migbase64.sourceforge.net/.
[edit] Seed7
The "encoding.s7i" library defines the functions toBase64 and fromBase64. The following example uses this functions:
const proc: checkBase64 (in string: stri) is func
begin
writeln(literal(toBase64(stri)));
if fromBase64(toBase64(stri)) <> stri then
writeln("Base64 conversions do not work for " <& literal(stri));
writeln(" " <& literal(fromBase64(toBase64(stri))));
end if;
end func;
In the "encoding.s7i" library toBase64 and toBase64 are defined as:
const func string: toBase64 (in string: stri) is func
result
var string: result is "";
local
const string: coding is "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var integer: index is 1;
var integer: subIndex is 1;
var char: ch is ' ';
var integer: threeBytes is 0;
var string: fourBytes is " ";
var integer: posToAddNewline is 58;
begin
for index range 1 to length(stri) step 3 do
threeBytes := 0;
for subIndex range index to index + 2 do
if subIndex <= length(stri) then
ch := stri[subIndex];
if ch >= '\256\' then
raise RANGE_ERROR;
end if;
else
ch := '\0\';
end if;
threeBytes := (threeBytes << 8) + ord(ch);
end for;
fourBytes @:= [1] coding[succ( threeBytes >> 18)];
fourBytes @:= [2] coding[succ((threeBytes >> 12) mod 64)];
fourBytes @:= [3] coding[succ((threeBytes >> 6) mod 64)];
fourBytes @:= [4] coding[succ( threeBytes mod 64)];
if index = posToAddNewline then
result &:= "\n";
posToAddNewline +:= 57;
end if;
result &:= fourBytes;
end for;
index := length(result);
if length(stri) rem 3 = 2 then
result @:= [index] '=';
elsif length(stri) rem 3 = 1 then
result @:= [index] '=';
result @:= [pred(index)] '=';
end if;
end func;
Original source: [1]
const func string: fromBase64 (in string: stri) is func
result
var string: result is "";
local
const array integer: decode is [] ( # -1 is illegal
62, -1, -1, -1, 63, # + /
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, # 0 - 9
-1, -1, -1, 0, -1, -1, -1, # =
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, # A - M
13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, # N - Z
-1, -1, -1, -1, -1, -1,
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, # a - m
39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51); # n - z
var integer: index is 1;
var integer: subIndex is 1;
var integer: number is 0;
var integer: fourBytes is 0;
var string: threeBytes is " ";
begin
while index <= length(stri) - 3 do
if stri[index] >= '+' then
fourBytes := 0;
for subIndex range index to index + 3 do
number := decode[ord(stri[subIndex]) - ord(pred('+'))];
if number = -1 then
raise RANGE_ERROR;
end if;
fourBytes := (fourBytes << 6) + number;
end for;
threeBytes @:= [1] chr( fourBytes >> 16);
threeBytes @:= [2] chr((fourBytes >> 8) mod 256);
threeBytes @:= [3] chr( fourBytes mod 256);
result &:= threeBytes;
index +:= 4;
elsif stri[index] = '\n' then
incr(index);
elsif stri[index] = '\r' or stri[succ(index)] = '\n' then
index +:= 2;
else
raise RANGE_ERROR;
end if;
end while;
if index <> succ(length(stri)) then
raise RANGE_ERROR;
end if;
if stri[length(stri) - 1 len 2] = "==" then
result := result[.. length(result) - 2];
elsif length(stri) >= 1 and stri[length(stri)] = '=' then
result := result[.. pred(length(result))];
end if;
end func;
Original source: [2]
