HttpWebRequest.Headers 屬性

定義

命名空間:

System.Net

組件:

System.Net.Requests.dll

來源:

HttpWebRequest.cs

指定組成 HTTP 標頭的名稱/值組集合。

public:
 virtual property System::Net::WebHeaderCollection ^ Headers { System::Net::WebHeaderCollection ^ get(); void set(System::Net::WebHeaderCollection ^ value); };

public override System.Net.WebHeaderCollection Headers { get; set; }

member this.Headers : System.Net.WebHeaderCollection with get, set

Public Overrides Property Headers As WebHeaderCollection

屬性值

WebHeaderCollection

WebHeaderCollection，其中包含組成 HTTP 要求標頭的名稱/值組。

例外狀況

InvalidOperationException

要求已透過呼叫 GetRequestStream()、BeginGetRequestStream(AsyncCallback, Object)、GetResponse()或 BeginGetResponse(AsyncCallback, Object) 方法來啟動。

範例

下列程式代碼範例會使用 Headers 屬性，將 HTTP 標頭名稱/ 值組列印至主控台。

// Create a new 'HttpWebRequest' Object to the mentioned URL.
HttpWebRequest^ myHttpWebRequest = (HttpWebRequest^)( WebRequest::Create( "http://www.contoso.com" ) );
// Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
HttpWebResponse^ myHttpWebResponse = (HttpWebResponse^)( myHttpWebRequest->GetResponse() );
Console::WriteLine( "\nThe HttpHeaders are \n\n\tName\t\tValue\n {0}", myHttpWebRequest->Headers );
// Print the HTML contents of the page to the console.
Stream^ streamResponse = myHttpWebResponse->GetResponseStream();
StreamReader^ streamRead = gcnew StreamReader( streamResponse );
array<Char>^ readBuff = gcnew array<Char>(256);
int count = streamRead->Read( readBuff, 0, 256 );
Console::WriteLine( "\nThe HTML contents of page the are  : \n\n " );
while ( count > 0 )
{
   String^ outputData = gcnew String( readBuff,0,count );
   Console::Write( outputData );
   count = streamRead->Read( readBuff, 0, 256 );
}
streamResponse->Close();
streamRead->Close();
// Release the HttpWebResponse Resource.
myHttpWebResponse->Close();

// Create a new 'HttpWebRequest' Object to the mentioned URL.
HttpWebRequest myHttpWebRequest=(HttpWebRequest)WebRequest.Create("http://www.contoso.com");
// Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
HttpWebResponse myHttpWebResponse=(HttpWebResponse)myHttpWebRequest.GetResponse();
Console.WriteLine("\nThe HttpHeaders are \n\n\tName\t\tValue\n{0}",myHttpWebRequest.Headers);
// Print the HTML contents of the page to the console.
Stream streamResponse=myHttpWebResponse.GetResponseStream();
StreamReader streamRead = new StreamReader( streamResponse );
Char[] readBuff = new Char[256];
int count = streamRead.Read( readBuff, 0, 256 );
Console.WriteLine("\nThe HTML contents of page the are  : \n\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();

     ' Create a new 'HttpWebRequest' Object to the mentioned URL.
     Dim myHttpWebRequest As HttpWebRequest = CType(WebRequest.Create("http://www.contoso.com"), HttpWebRequest)
     ' Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
     Dim myHttpWebResponse As HttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)
     Console.WriteLine(ControlChars.Cr + "The HttpHeaders are " + ControlChars.Cr + ControlChars.Cr + ControlChars.Tab + "Name" + ControlChars.Tab + ControlChars.Tab + "Value" + ControlChars.Cr + "{0}", myHttpWebRequest.Headers)

     ' Print the HTML contents of the page to the console. 
     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 HTML contents of page the are  : " + ControlChars.Cr + 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()

備註

謹慎

WebRequest、HttpWebRequest、ServicePoint和 WebClient 已經過時，您不應該將它們用於新的開發。 請改用 HttpClient。

Headers 集合包含與要求相關聯的通訊協議標頭。 下表列出未儲存在 Headers 集合中的 HTTP 標頭，但是由系統設定，或由屬性或方法設定。

頁眉	設定者
接受	由 Accept 屬性設定。
連接	由 Connection 屬性和 KeepAlive 屬性設定。
Content-Length	由 ContentLength 屬性設定。
Content-Type	由 ContentType 屬性設定。
期望	由 Expect 屬性設定。
日期	由 Date 屬性設定。
主機	由 Host 屬性設定。
If-Modified-Since	由 IfModifiedSince 屬性設定。
範圍	由 AddRange 方法設定。
參考者	由 Referer 屬性設定。
Transfer-Encoding	由 TransferEncoding 屬性設定 （SendChunked 屬性必須為 true）。
User-Agent	由 UserAgent 屬性設定。

如果您嘗試設定其中一個受保護的標頭，Add 方法會擲回 ArgumentException。

呼叫 GetRequestStream、BeginGetRequestStream、GetResponse或 BeginGetResponse 方法，以在要求啟動之後變更 Headers 屬性，會擲回 InvalidOperationException。

您不應該假設標頭值會保持不變，因為 Web 伺服器和快取可能會變更或新增標頭至 Web 要求。