MD5加密之提取文件的MD5特征码

public static String encodeFile(String path) {

        try {
            MessageDigest digester = MessageDigest.getInstance("MD5");
            
            FileInputStream in = new FileInputStream(path);
            
            byte[] bytes = new byte[1024];
            int byteCount;
            while ((byteCount = in.read(bytes)) > 0) {
                digester.update(bytes, 0, byteCount);
            }
            byte[] digest = digester.digest();
            
            //用StringBuffer拼接字节数组
            StringBuffer sb = new StringBuffer();
            for (byte b : digest) {
                String str = Integer.toHexString(b & 0xff);
                if(str.length() == 1){
                    str = "0" + str;
                }
                sb.append(str);
            }
            in.close();
            
            return sb.toString();
            
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }