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<in.getBytes().length;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(); 
}