java实现维吉尼亚密码加解密算法(附完整源码)

以下是Java实现维吉尼亚密码加解密算法的完整源码：

import java.util.Scanner;

public class VigenereCipher {
    private static final String ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // 读取明文和密钥
        System.out.print("请输入明文：");
        String plainText = scanner.nextLine().toUpperCase();
        System.out.print("请输入密钥：");
        String key = scanner.nextLine().toUpperCase();

        // 加密
        String cipherText = encrypt(plainText, key);
        System.out.println("加密后的密文为：" + cipherText);

        // 解密
        String decryptedText = decrypt(cipherText, key);
        System.out.println("解密后的明文为：" + decryptedText);

        scanner.close();
    }

    /**
     * 维吉尼亚密码加密
     *
     * @param plainText 明文
     * @param key       密钥
     * @return 密文
     */
    public static String encrypt(String plainText, String key) {
        StringBuilder cipherText = new StringBuilder();
        int keyIndex = 0;

        for (char c : plainText.toCharArray()) {
            if (Character.isLetter(c)) {
                int plainTextIndex = ALPHABET.indexOf(c);
                int keyCharIndex = ALPHABET.indexOf(key.charAt(keyIndex));
                int cipherTextIndex = (plainTextIndex + keyCharIndex) % ALPHABET.length();
                cipherText.append(ALPHABET.charAt(cipherTextIndex));
                keyIndex = ++keyIndex % key.length();
            } else {
                cipherText.append(c);
            }
        }

        return cipherText.toString();
    }

    /**
     * 维吉尼亚密码解密
     *
     * @param cipherText 密文
     * @param key        密钥
     * @return 明文
     */
    public static String decrypt(String cipherText, String key) {
        StringBuilder plainText = new StringBuilder();
        int keyIndex = 0;

        for (char c : cipherText.toCharArray()) {
            if (Character.isLetter(c)) {
                int cipherTextIndex = ALPHABET.indexOf(c);
                int keyCharIndex = ALPHABET.indexOf(key.charAt(keyIndex));
                int plainTextIndex = (cipherTextIndex - keyCharIndex + ALPHABET.length()) % ALPHABET.length();
                plainText.append(ALPHABET.charAt(plainTextIndex));
                keyIndex = ++keyIndex % key.length();
            } else {
                plainText.append(c);
            }
        }

        return plainText.toString();
    }
}

使用时，只需在主函数中调用 `encrypt` 和 `decrypt` 方法即可。注意，这里使用的是大写字母表，如果要支持小写字母，可以在字母表中添加小写字母即可。