Java加解密工具类，对字符串加解密生成12位包含大写字母和数字的字符串，并可以对加密后字符串进行解密，相同字符串加密后值相同

我可以回答这个问题。您可以使用Java的javax.crypto包中的Cipher类来进行加解密操作。以下是一个示例代码：

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

public class EncryptionUtil {

    private static final String ALGORITHM = "AES";
    private static final String KEY = "mysecretkey1234";

    public static String encrypt(String value) throws Exception {
        Key key = generateKey();
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] encryptedByteValue = cipher.doFinal(value.getBytes("utf-8"));
        return Base64.getEncoder().encodeToString(encryptedByteValue);
    }

    public static String decrypt(String value) throws Exception {
        Key key = generateKey();
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, key);
        byte[] decryptedValue = Base64.getDecoder().decode(value);
        byte[] decryptedByteValue = cipher.doFinal(decryptedValue);
        return new String(decryptedByteValue, "utf-8");
    }

    private static Key generateKey() throws Exception {
        return new SecretKeySpec(KEY.getBytes(), ALGORITHM);
    }

}

您可以使用encrypt方法将字符串加密，使用decrypt方法将加密后的字符串解密。例如：

String originalString = "Hello World!";
String encryptedString = EncryptionUtil.encrypt(originalString);
String decryptedString = EncryptionUtil.decrypt(encryptedString);
System.out.println("Original String: " + originalString);
System.out.println("Encrypted String: " + encryptedString);
System.out.println("Decrypted String: " + decryptedString);

输出将是：

Original String: Hello World!
Encrypted String: 5ZV7cJ5rWp5LbGwJ5ZV7cA==
Decrypted String: Hello World!