文件加密解密

/**
     * 加密文件infilename,输出加密后的文件outfilename 返回AES加密密钥
     */
    public static byte[] AesEnCrypt(String infilename, String outfilename)
            throws Exception {
        KeyGenerator keyGen = KeyGenerator.getInstance("AES");
        keyGen.init(128);
        SecretKey key = keyGen.generateKey();

        Cipher cipher = Cipher.getInstance("AES");

        InputStream in = new FileInputStream(infilename);
        DataOutputStream out = new DataOutputStream(new FileOutputStream(
                outfilename));

        cipher.init(Cipher.ENCRYPT_MODE, key);
        crypt(in, out, cipher);

        in.close();
        out.close();
        return key.getEncoded();
    }

    /**
     * 用密钥k解密文件infilename,输出明文文件outfilename
     *
     * @param infilename
     * @param outfilename
     * @param k
     */
    public static void AesDeCrypt(String infilename, String outfilename,
            byte[] k) {

        try {

            Cipher cipher = Cipher.getInstance("AES");

            SecretKey key = new javax.crypto.spec.SecretKeySpec(k, "AES");
            OutputStream out = new FileOutputStream(outfilename);
            DataInputStream in = new DataInputStream(new FileInputStream(
                    infilename));

            cipher.init(Cipher.DECRYPT_MODE, key);
            crypt(in, out, cipher);

            in.close();
            out.close();

        } catch (GeneralSecurityException exception) {
            exception.printStackTrace();
        } catch (IOException exception) {
            exception.printStackTrace();
        }

    }

    /**
     * 自己定义的加 密函数
     *
     * @param in
     * @param out
     * @param cipher
     * @throws IOException
     * @throws GeneralSecurityException
     */
    public static void crypt(InputStream in, OutputStream out, Cipher cipher)
            throws IOException, GeneralSecurityException {
        int blockSize = cipher.getBlockSize();
        int outputSize = cipher.getOutputSize(blockSize);
        byte[] inBytes = new byte[blockSize];
        byte[] outBytes = new byte[outputSize];
        int inLength = 0;
        boolean more = true;
        while (more) {
            inLength = in.read(inBytes);
            if (inLength == blockSize) {
                int outLength = cipher.update(inBytes, 0, blockSize, outBytes);
                out.write(outBytes, 0, outLength);
            } else {
                more = false;
            }
        }
        if (inLength > 0)
            outBytes = cipher.doFinal(inBytes, 0, inLength);
        else
            outBytes = cipher.doFinal();
        out.write(outBytes);
    }



    public static String crypt(String in,Cipher cipher)
    throws IOException, GeneralSecurityException {
        StringBuffer out = new StringBuffer();
        int blockSize = cipher.getBlockSize();
        int outputSize = cipher.getOutputSize(blockSize);
        byte[] inBytes = new byte[blockSize];
        byte[] outBytes = new byte[outputSize];
        int inLength = 0;
        boolean more = true;
        while (more) {
            for(int i = 0;i
            {
                System.out.println(in.getBytes().length*8);
                if(in.getBytes().length>=i*blockSize)
                {
                    System.arraycopy(in, 0*blockSize, inBytes, 0, blockSize);
                    cipher.update(inBytes, 0, blockSize, outBytes);
                    out.append(outBytes);
                }
                else
                {
                    inLength = in.getBytes().length - i*blockSize;
                    more = false;
                }
            }
        }
        if (inLength > 0)
            outBytes = cipher.doFinal(inBytes, 0, inLength);
        else
            outBytes = cipher.doFinal();
        out.append(outBytes);
        return out.toString();
}