Base64 library

Base64 library converts bytes to the base64 representation and vice versa.

Base64 encoding is described in RFC 1421 and RFC 2045.

Base64Helper class contains methods to convert the byte array to the base64 string, to convert the base64 string to the byte array and to check, if the string is a base64 representation of bytes.

An example, how to convert the byte array to the base64 string:

String str1 = Base64Helper.toBase64(new byte[]{1, 5, (byte) 140, (byte) 250, -14, 25}); // str1 = "AQWM+vIZ"
String str2 = Base64Helper.toBase64(new byte[]{(byte) 255, (byte) 250, (byte) 180, 17, 94}); // str2 = "//q0EV4="
String str3 = Base64Helper.toBase64(new byte[]{17, 28, (byte) 179, -14}); // str3 = "ERyz8g=="

An example, how to convert the base64 string to the byte array:

byte[] bytes1 = Base64Helper.toBytes("a+Z/fF12"); // bytes1 = new byte[]{(107, (byte) 230, 127, 124, 93, 118}
byte[] bytes2 = Base64Helper.toBytes("12gE3JQ="); // bytes2 = new byte[]{(byte) 215, 104, 4, (byte) 220, (byte) 148}
byte[] bytes3 = Base64Helper.toBytes("0FFTyQ=="); // bytes3 = new byte[]{(byte) 208, 81, 83, (byte) 201}

Base64Helper class contains all data in memory. For the large data (for example, big files) this is not efficient. In this case Base64InputStream and Base64OutputStream classes can be used. Base64InputStream reads the stream of the base64 characters and translates them to the bytes. Base64OutputStream translates the bytes to the base64 characters and writes them to the stream.

An example, how to write the base64 characters to the file:

try (FileInputStream inputStream = new FileInputStream("input file");
     Base64OutputStream outputStream = new Base64OutputStream(new FileOutputStream("base64 output file"))) {
    int read;
    while (true) {
        read = inputStream.read();
        if (read < 0) {
            break;
        }
        outputStream.write(read);
    }
}

Each 3 original bytes are represented with 4 base64 characters. The base64 representation of bytes increases the original size by 33 percent.