Notes for 2008-11(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