Notes for 200811(GetRange, backup,file hash, PostRequest, QueryString)

1、List<T>泛型中并没有实现ICloneable接口，也就是没有实出Clone方法，所以我们在克隆一个List时可以使用GetRange方法来代替它。

List<int> oldList = new List();
oldList.Add(1);
oldList.Add(2);
List<int> newList = oldList.GetRange(0,oldList.Count);

2、 backup数据库

BACKUP DATABASE ProfileDB TO DISK = 'D:\FULL_DATA\ProfileDB.bak' 
WITH checksum, INIT, NOUNLOAD, NAME=N'ProfileDB Full backup', SKIP, STATS = 10, NOFORMAT

3、计算文件的Hash值:

    protected void Page_Load(object sender, EventArgs e)
    {
        string filePath = Request.PhysicalPath;
        string hash = string.Empty;
        using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))
        {
            using (MD5 md5 = MD5.Create())
            {
                byte[] hashData = md5.ComputeHash(fs);
                hash = ConvertToHexString(hashData);
                md5.Clear();
            }
            fs.Close();
        }
        Response.Write(hash);
    }
    private static string ConvertToHexString(byte[] bytes)
    {
        int length = bytes.Length;
        StringBuilder sb = new StringBuilder();
        foreach (byte data in bytes)
        {
            sb.Append(data.ToString("x2"));
        }
        return sb.ToString();
    }

hash结果都是以32个字符来表示的16进制串，通过对每位招行ToString("x2")实现。

4、封装对某一页面Post和Get操作。

        /// <summary>
        /// 通过Post和Get方式请求页面
        /// </summary>
        /// <param name="url">需要Post到的页面url</param>
        /// <param name="postData">post数据的字典</param>
        /// <param name="queryData">get查询的字典</param>
        /// <param name="timeout">超时时间(毫秒)</param>
        /// <returns>请求后的返回</returns>
        public static string RequestUrl(string url, IDictionary<string, string> postData, IDictionary<string, string> queryData, int timeout)
        {
            //参数验证
            if (url.IndexOfAny(new char[] { '?', '&' }) > -1)
                throw new ArgumentException("url不应该带参数");
            if (!url.StartsWith("http://"))
                throw new ArgumentException("url必须以\"http://\"开头");
            if (postData == null)
                postData = new Dictionary<string, string>();
            if (queryData == null)
                queryData = new Dictionary<string, string>();

            //构造url
            StringBuilder urlBuilder = new StringBuilder();
            foreach (var kv in queryData)
            {
                urlBuilder.Append(string.Format(CultureInfo.InvariantCulture, "{0}={1}&", kv.Key, HttpUtility.UrlEncode(kv.Value)));
            }
            string suffix = urlBuilder.Length > 0 ? ("?" + urlBuilder.ToString().TrimEnd('&')) : "";
            string postUrl = url + suffix;

            //构造Post数据
            StringBuilder dataBuilder = new StringBuilder();
            foreach (var kv in postData)
            {
                dataBuilder.Append(string.Format(CultureInfo.InvariantCulture, "{0}={1}&", kv.Key, kv.Value));
            }
            string data = dataBuilder.Length > 0 ? dataBuilder.ToString().TrimEnd('&') : "";
            byte[] dataBytes = Encoding.UTF8.GetBytes(data);

            //发出请求
            string content = string.Empty;

            //HttpWebRequest
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(postUrl);
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
            request.ContentLength = dataBytes.Length;
            request.Timeout = timeout;

            try
            {
                //把dataBytes写入HttpWebRequest
                using (Stream requestStream = request.GetRequestStream())
                {
                    requestStream.Write(dataBytes, 0, dataBytes.Length);
                    requestStream.Close();
                }
                //获取HttpWebResponse
                using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
                {
                    if (response.StatusCode == HttpStatusCode.OK)
                    {
                        using (Stream stream = response.GetResponseStream())
                        {
                            using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
                            {
                                content = reader.ReadToEnd();
                                reader.Close();
                            }
                            stream.Close();
                        }
                    }
                    response.Close();
                }
            }
            catch (System.Net.WebException) { }
            finally
            {
                if (request != null)
                {
                    request.Abort();
                    request = null;
                }
            }

            return content;
        }

5、Request.QueryString里对查询字符串强制进行了一次UrlDecode，但如何使用Request["id"]方式获取查询值时则需要手工进行一次UrlDecode