Java : Base64.Encoder with Examples
December 10, 2023 
February 9, 2022
Base64.Encoder (Java SE 19 & JDK 19) API Examples.
You will find code examples on most Base64.Encoder methods.
Summary
This class implements an encoder for encoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
final var encoder = Base64.getEncoder();
final byte[] src = {1, 2, 3, 4, 5, 6, 7};
final var dst = encoder.encodeToString(src);
System.out.println(dst); // AQIDBAUGBw==
final var decoder = Base64.getDecoder();
final var decoded = decoder.decode(dst);
System.out.println(Arrays.toString(decoded)); // [1, 2, 3, 4, 5, 6, 7]
Methods
byte[] encode (byte[] src)
Encodes all bytes from the specified byte array into a newly-allocated byte array using the Base64 encoding scheme.
final var encoder = Base64.getEncoder();
final byte[] src = {1, 2, 3, 4, 5, 6, 7};
final var dst = encoder.encode(src);
System.out.println(Arrays.toString(dst)); // [65, 81, 73, 68, 66, 65, 85, 71, 66, 119, 61, 61]
System.out.println(new String(dst)); // AQIDBAUGBw==
int encode (byte[] src, byte[] dst)
Encodes all bytes from the specified byte array using the Base64 encoding scheme, writing the resulting bytes to the given output byte array, starting at offset 0.
final var encoder = Base64.getEncoder();
final byte[] src = {1, 2, 3, 4, 5, 6, 7};
final byte[] dst = new byte[src.length * 2 + 4]; // With a little margin.
final var size = encoder.encode(src, dst);
System.out.println(size); // 12
System.out.println(Arrays.toString(dst)); // [65, 81, 73, 68, 66, 65, 85, 71, 66, 119, 61, 61, 0, 0, 0, 0, 0, 0]
System.out.println(new String(dst, 0, size)); // AQIDBAUGBw==
ByteBuffer encode (ByteBuffer buffer)
Encodes all remaining bytes from the specified byte buffer into a newly-allocated ByteBuffer using the Base64 encoding scheme.
final var encoder = Base64.getEncoder();
final byte[] src = {1, 2, 3, 4, 5, 6, 7};
final var srcBuffer = ByteBuffer.wrap(src);
final var dstBuffer = encoder.encode(srcBuffer);
System.out.println(dstBuffer); // java.nio.HeapByteBuffer[pos=0 lim=12 cap=12]
final var dst = dstBuffer.array();
System.out.println(Arrays.toString(dst)); // [65, 81, 73, 68, 66, 65, 85, 71, 66, 119, 61, 61]
System.out.println(new String(dst)); // AQIDBAUGBw==
String encodeToString (byte[] src)
Encodes the specified byte array into a String using the Base64 encoding scheme.
final var encoder = Base64.getEncoder();
final byte[] src = {1, 2, 3, 4, 5, 6, 7};
final var dst = encoder.encodeToString(src);
System.out.println(dst); // AQIDBAUGBw==
Base64.Encoder withoutPadding ()
Returns an encoder instance that encodes equivalently to this one, but without adding any padding character at the end of the encoded byte data.
final var encoder1 = Base64.getEncoder();
final var encoder2 = encoder1.withoutPadding();
final byte[] src = {1, 2, 3, 4, 5, 6, 7};
final var dst1 = encoder1.encodeToString(src);
final var dst2 = encoder2.encodeToString(src);
System.out.println(dst1); // AQIDBAUGBw==
System.out.println(dst2); // AQIDBAUGBw
OutputStream wrap (OutputStream os)
Wraps an output stream for encoding byte data using the Base64 encoding scheme.
final var path = Path.of("R:", "java-work", "sample.txt");
System.out.println(path); // R:\java-work\sample.txt
final var encoder = Base64.getEncoder();
final byte[] src = {1, 2, 3, 4, 5, 6, 7};
try (final var outputStream = encoder.wrap(Files.newOutputStream(path))) {
outputStream.write(src);
}
final var dst = Files.readString(path);
System.out.println(dst); // AQIDBAUGBw==
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