HttpWebRequest.UserAgent 属性    
定义
重要
一些信息与预发行产品相关,相应产品在发行之前可能会进行重大修改。 对于此处提供的信息,Microsoft 不作任何明示或暗示的担保。
获取或设置 User-agent HTTP 标头的值。
public:
 property System::String ^ UserAgent { System::String ^ get(); void set(System::String ^ value); };
	public string? UserAgent { get; set; }
	public string UserAgent { get; set; }
	member this.UserAgent : string with get, set
	Public Property UserAgent As String
	属性值
              User-agent HTTP 标头的值。 默认值为 null。
示例
下面的代码示例设置 UserAgent 属性。
// Create a new 'HttpWebRequest' object to the mentioned URL.
HttpWebRequest myHttpWebRequest=(HttpWebRequest)WebRequest.Create("http://www.contoso.com");
myHttpWebRequest.UserAgent=".NET Framework Test Client";
// Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
HttpWebResponse myHttpWebResponse=(HttpWebResponse)myHttpWebRequest.GetResponse();
// Display the 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 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);
}
// Release the response object resources.
streamRead.Close();
streamResponse.Close();
myHttpWebResponse.Close();
 ' Create a new 'HttpWebRequest' object to the mentioned URL.
  Dim myHttpWebRequest As HttpWebRequest = CType(WebRequest.Create("http://www.contoso.com"), HttpWebRequest)
  myHttpWebRequest.UserAgent= ".NET Framework Test Client"
  ' The response object of 'HttpWebRequest' is assigned to a 'HttpWebResponse' variable.
  Dim myHttpWebResponse As HttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)
  ' Display the 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 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
  streamRead.Close()
   streamResponse.Close()    
' Release the response object resources.
   myHttpWebResponse.Close()
	注解
谨慎
              WebRequest、HttpWebRequest、ServicePoint和 WebClient 已过时,不应将其用于新开发。 请改用 HttpClient。
此属性的值存储在 WebHeaderCollection中。 如果设置了 WebHeaderCollection,则属性值将丢失。