? Base64 Encoding & Decoding

? Quick Overview

Base64 is a binary-to-text encoding scheme used to safely transmit binary data (such as images, files, or encrypted bytes) over text-based protocols like HTTP, JSON, and XML. In Advanced Java, Base64 encoding and decoding is commonly handled using the java.util.Base64 class.

? Key Concepts

• Encodes binary data into ASCII characters
• Uses characters A–Z, a–z, 0–9, +, / and = (padding)
• Not encryption — only encoding
• Widely used in JWT, REST APIs, file uploads, and email

? Syntax & Theory

Java 8 introduced the Base64 utility class which provides encoders and decoders for different use cases.

• Basic Standard Base64 encoding
• URL URL-safe encoding
• MIME MIME-friendly encoding with line breaks

? Code Example — Encoding

// Encode a string into Base64 format
import java.util.Base64;

public class Base64EncodeExample {
public static void main(String[] args) {
String original = "Advanced Java";
String encoded = Base64.getEncoder().encodeToString(original.getBytes());
System.out.println(encoded);
}
}

? Code Example — Decoding

// Decode a Base64 encoded string back to original text
import java.util.Base64;

public class Base64DecodeExample {
public static void main(String[] args) {
String encoded = "QWR2YW5jZWQgSmF2YQ==";
byte[] decodedBytes = Base64.getDecoder().decode(encoded);
String decoded = new String(decodedBytes);
System.out.println(decoded);
}
}

? Live Output / Explanation