Android AES加密Cipher.doFinal之后缺失字节的问题可能是由于编码问题导致的。以下是一种可能的解决方法：

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.util.Base64;

public class AESUtil {
    private static final String AES_ALGORITHM = "AES/CBC/PKCS5Padding";
    private static final String AES_KEY = "YourSecretKey";
    private static final String AES_IV = "YourInitializationVector";

    public static String encrypt(String data) throws Exception {
        Cipher cipher = Cipher.getInstance(AES_ALGORITHM);
        SecretKeySpec secretKeySpec = new SecretKeySpec(AES_KEY.getBytes(StandardCharsets.UTF_8), "AES");
        IvParameterSpec ivParameterSpec = new IvParameterSpec(AES_IV.getBytes(StandardCharsets.UTF_8));
        cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec);
        byte[] encryptedBytes = cipher.doFinal(data.getBytes(StandardCharsets.UTF_8));
        return Base64.getEncoder().encodeToString(encryptedBytes);
    }

    public static String decrypt(String encryptedData) throws Exception {
        Cipher cipher = Cipher.getInstance(AES_ALGORITHM);
        SecretKeySpec secretKeySpec = new SecretKeySpec(AES_KEY.getBytes(StandardCharsets.UTF_8), "AES");
        IvParameterSpec ivParameterSpec = new IvParameterSpec(AES_IV.getBytes(StandardCharsets.UTF_8));
        cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec);
        byte[] decryptedBytes = cipher.doFinal(Base64.getDecoder().decode(encryptedData));
        return new String(decryptedBytes, StandardCharsets.UTF_8);
    }
}

使用上述代码，你可以通过以下方式进行AES加密和解密：

String originalData = "Hello World";
String encryptedData = AESUtil.encrypt(originalData);
String decryptedData = AESUtil.decrypt(encryptedData);

请确保AES_KEY和AES_IV的值与加密和解密时使用的密钥和初始化向量匹配。