HttpWebRequest.IfModifiedSince プロパティ

If-Modified-Since HTTP ヘッダーの値を取得または設定します。

Public Property IfModifiedSince As DateTime
[C#]
public DateTime IfModifiedSince {get; set;}
[C++]
public: __property DateTime get_IfModifiedSince();public: __property void set_IfModifiedSince(DateTime);
[JScript]
public function get IfModifiedSince() : DateTime;public function set IfModifiedSince(DateTime);

プロパティ値

If-Modified-Since HTTP ヘッダーの内容を格納する DateTime 。既定値は、現在の日付と時刻です。

解説

IfModifiedSince プロパティは、現地時間であると想定されます。

使用例

[Visual Basic, C#, C++] IfModifiedSince プロパティを確認する例を次に示します。

 
' Create a new 'Uri' object with the mentioned string.
Dim myUri As New Uri("https://www.contoso.com")
' Create a new 'HttpWebRequest' object with the above 'Uri' object.
Dim myHttpWebRequest As HttpWebRequest = CType(WebRequest.Create(myUri), HttpWebRequest)
' Create a new 'DateTime' object.
Dim today As DateTime = DateTime.Now
If DateTime.Compare(today, myHttpWebRequest.IfModifiedSince) = 0 Then
    ' Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
    Dim myHttpWebResponse As HttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)
    Console.WriteLine("Response headers " + ControlChars.Cr + "{0}" + ControlChars.Cr, myHttpWebResponse.Headers)
    Dim streamResponse As Stream = myHttpWebResponse.GetResponseStream()
    Dim streamRead As New StreamReader(streamResponse)
    Dim readBuff(256) As [Char]
    Dim count As Integer = streamRead.Read(readBuff, 0, 256)
    Console.WriteLine(ControlChars.Cr + "The contents of Html Page are :  " + ControlChars.Cr)
    While count > 0
        Dim outputData As New [String](readBuff, 0, count)
        Console.Write(outputData)
        count = streamRead.Read(readBuff, 0, 256)
    End While
           ' Close the Stream object.
        streamResponse.Close()
        streamRead.Close()
           ' Release the HttpWebResponse Resource.
        myHttpWebResponse.Close()
    Console.WriteLine(ControlChars.Cr + "Press 'Enter' key to continue.................")
    Console.Read()
Else
    Console.WriteLine((ControlChars.Cr + "The page has been modified since " + today))
End If

[C#] 
// Create a new 'Uri' object with the mentioned string.
Uri myUri =new Uri("https://www.contoso.com");            
// Create a new 'HttpWebRequest' object with the above 'Uri' object.
HttpWebRequest myHttpWebRequest= (HttpWebRequest)WebRequest.Create(myUri);
// Create a new 'DateTime' object.
DateTime today= DateTime.Now;
if (DateTime.Compare(today,myHttpWebRequest.IfModifiedSince)==0)
{
    // Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
    HttpWebResponse myHttpWebResponse=(HttpWebResponse)myHttpWebRequest.GetResponse();
    Console.WriteLine("Response headers \n{0}\n",myHttpWebResponse.Headers);
    Stream streamResponse=myHttpWebResponse.GetResponseStream();
    StreamReader streamRead = new StreamReader( streamResponse );
    Char[] readBuff = new Char[256];
    int count = streamRead.Read( readBuff, 0, 256 );
    Console.WriteLine("\nThe contents of Html Page are :  \n");    
    while (count > 0) 
    {
        String outputData = new String(readBuff, 0, count);
        Console.Write(outputData);
        count = streamRead.Read(readBuff, 0, 256);
    }
    // Close the Stream object.
    streamResponse.Close();
    streamRead.Close();
    // Release the HttpWebResponse Resource.
    myHttpWebResponse.Close();
    Console.WriteLine("\nPress 'Enter' key to continue.................");    
    Console.Read();
}
else
{
    Console.WriteLine("\nThe page has been modified since "+today);
}

[C++] 
// Create a new 'Uri' object with the mentioned string.
Uri* myUri = new Uri(S"https://www.contoso.com");
// Create a new 'HttpWebRequest' object with the above 'Uri' object.
HttpWebRequest* myHttpWebRequest =
   dynamic_cast<HttpWebRequest*>(WebRequest::Create(myUri));
// Create a new 'DateTime' object.
DateTime today = DateTime::Now;
if (DateTime::Compare(today, myHttpWebRequest->IfModifiedSince)==0) {
   // Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
   HttpWebResponse* myHttpWebResponse =
      dynamic_cast<HttpWebResponse*>(myHttpWebRequest->GetResponse());
   Console::WriteLine(S"Response headers \n {0}\n",
      myHttpWebResponse->Headers);
   Stream* streamResponse = myHttpWebResponse->GetResponseStream();
   StreamReader* streamRead = new StreamReader(streamResponse);
   Char readBuff[] = new Char[256];
   int count = streamRead->Read(readBuff, 0, 256);
   Console::WriteLine(S"\nThe contents of Html Page are :  \n");
   while (count > 0) {
      String* outputData = new String(readBuff, 0, count);
      Console::Write(outputData);
      count = streamRead->Read(readBuff, 0, 256);
   }
   // Close the Stream object.
   streamResponse->Close();
   streamRead->Close();
   // Release the HttpWebResponse Resource.
   myHttpWebResponse->Close();
   Console::WriteLine(S"\nPress 'Enter' key to continue.................");
   Console::Read();
} else {
   Console::WriteLine(S"\nThe page has been modified since {0}", __box( today));
}

[JScript] JScript のサンプルはありません。Visual Basic、C#、および C++ のサンプルを表示するには、このページの左上隅にある言語のフィルタ ボタン をクリックします。

必要条件

プラットフォーム: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 ファミリ, .NET Compact Framework - Windows CE .NET, Common Language Infrastructure (CLI) Standard

参照

HttpWebRequest クラス | HttpWebRequest メンバ | System.Net 名前空間