java Aes 用一个字符串 加密另一个字符串 生成一个新的字符串

在Java中，我们可以使用`javax.crypto.Cipher`和`javax.crypto.spec.SecretKeySpec`类配合`AES`（Advanced Encryption Standard）算法来进行字符串加密。这里是一个简单的例子，假设你有一个预共享的密钥作为字符串：

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

public class AESExample {
    private static final String ALGORITHM = "AES";
    private static final byte[] keyValue = // 你的密钥字符串转为字节数组，例如 "mysecretkey".getBytes();

    public static String encrypt(String plainText) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(keyValue, ALGORITHM);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);

        byte[] encryptedBytes = cipher.doFinal(plainText.getBytes("UTF-8"));
        return Base64.getEncoder().encodeToString(encryptedBytes);
    }

    public static String decrypt(String encryptedText) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(keyValue, ALGORITHM);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, secretKey);

        byte[] decryptedBytes = cipher.doFinal(Base64.getDecoder().decode(encryptedText));
        return new String(decryptedBytes, "UTF-8");
    }

    public static void main(String[] args) throws Exception {
        String inputString = "Hello, World!";
        String encrypted = encrypt(inputString);
        System.out.println("Encrypted: " + encrypted);
        String decrypted = decrypt(encrypted);
        System.out.println("Decrypted: " + decrypted);
    }
}

这个示例首先将明文字符串转换为字节，然后使用AES加密，最后将加密后的字节编码成Base64字符串以便于存储和传输。解密时，再从Base64字符串还原并解密回原始文本。