在java中的简单凯撒密码

public static String encryptCaesarCipher(String input, int shift) {
    StringBuilder encrypted = new StringBuilder();
    for (char c : input.toCharArray()) {
        if (Character.isLetter(c)) {
            int base = Character.isLowerCase(c) ? 'a' : 'A';
            encrypted.append((char) (((c - base + shift) % 26) + base));
        } else {
            encrypted.append(c);
        }
    }
    return encrypted.toString();
}

public static String decryptCaesarCipher(String input, int shift) {
    StringBuilder decrypted = new StringBuilder();
    for (char c : input.toCharArray()) {
        if (Character.isLetter(c)) {
            int base = Character.isLowerCase(c) ? 'a' : 'A';
            decrypted.append((char) (((c - base - shift + 26) % 26) + base));
        } else {
            decrypted.append(c);
        }
    }
    return decrypted.toString();
}

public static void main(String[] args) {
    String input = "Hello, World!";
    int shift = 3;

    String encrypted = encryptCaesarCipher(input, shift);
    System.out.println("Encrypted: " + encrypted);

    String decrypted = decryptCaesarCipher(encrypted, shift);
    System.out.println("Decrypted: " + decrypted);
}

Encrypted: Khoor, Zruog!
Decrypted: Hello, World!