生成符合AES要求的密钥

 public static byte[] generateDesKey(int length) throws Exception {
        //实例化  
        KeyGenerator kgen = null;
        kgen = KeyGenerator.getInstance("AES");
        //设置密钥长度  
        kgen.init(length);  
        //生成密钥  
        SecretKey skey = kgen.generateKey();  
        //返回密钥的二进制编码  
        return skey.getEncoded();  
    }

byte[] aesKey = generateDesKey(256);

AES加密

 public static byte[] Aes256Encode(String str, byte[] key) throws Exception {
        byte[] result = null;
        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
        Cipher cipher = Cipher.getInstance(ALGORITHM, "BC");
        SecretKeySpec keySpec = new SecretKeySpec(key, "AES"); // 生成加密解密需要的Key
        cipher.init(Cipher.ENCRYPT_MODE, keySpec);
        result = cipher.doFinal(str.getBytes("UTF-8"));
        return result;
    }

public static final String ALGORITHM = "AES/ECB/PKCS5Padding";