WebClient 建構函式
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
警告
WebRequest, HttpWebRequest, ServicePoint, and WebClient are obsolete. Use HttpClient instead.
初始化 WebClient 類別的新執行個體。
public:
WebClient();C#
public WebClient();C#
[System.Obsolete("WebRequest, HttpWebRequest, ServicePoint, and WebClient are obsolete. Use HttpClient instead.", DiagnosticId="SYSLIB0014", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
public WebClient();Public Sub New ()- 屬性
下列程式代碼範例會 WebClient 建立 實例，然後使用它從伺服器下載數據，並在系統控制台上顯示數據、從伺服器下載數據，並將它寫入檔案，以及將窗體值上傳至伺服器並接收回應。
try
{
// Download the data to a buffer.
WebClient^ client = gcnew WebClient;
array<Byte>^ pageData = client->DownloadData( "http://www.contoso.com" );
String^ pageHtml = Encoding::ASCII->GetString( pageData );
Console::WriteLine( pageHtml );
// Download the data to a file.
client->DownloadFile( "http://www.contoso.com", "page.htm" );
// Upload some form post values.
NameValueCollection^ form = gcnew NameValueCollection;
form->Add( "MyName", "MyValue" );
array<Byte>^ responseData = client->UploadValues( "http://www.contoso.com/form.aspx", form );
}
catch ( WebException^ webEx )
{
Console::WriteLine( webEx->ToString() );
if ( webEx->Status == WebExceptionStatus::ConnectFailure )
{
Console::WriteLine( "Are you behind a firewall? If so, go through the proxy server." );
}
}
C#
try {
// Download the data to a buffer.
WebClient client = new WebClient();
Byte[] pageData = client.DownloadData("http://www.contoso.com");
string pageHtml = Encoding.ASCII.GetString(pageData);
Console.WriteLine(pageHtml);
// Download the data to a file.
client.DownloadFile("http://www.contoso.com", "page.htm");
// Upload some form post values.
NameValueCollection form = new NameValueCollection();
form.Add("MyName", "MyValue");
Byte[] responseData = client.UploadValues("http://www.contoso.com/form.aspx", form);
}
catch (WebException webEx) {
Console.WriteLine(webEx.ToString());
if(webEx.Status == WebExceptionStatus.ConnectFailure) {
Console.WriteLine("Are you behind a firewall? If so, go through the proxy server.");
}
}
Public Shared Sub Main()
Try
Dim client As New WebClient()
Dim pageData As [Byte]() = client.DownloadData("http://www.contoso.com")
Dim pageHtml As String = Encoding.ASCII.GetString(pageData)
' Download the data to a buffer.
Console.WriteLine(pageHtml)
' Download the data to a file.
client.DownloadFile("http://www.contoso.com", "page.htm")
' Upload some form post values.
dim form as New NameValueCollection()
form.Add("MyName", "MyValue")
' Note that you need to replace "http://localhost/somefile.aspx" with the name of
' a file that is available to your computer.
Dim responseData As [Byte]() = client.UploadValues("http://www.contoso.com/form.aspx", form)
Console.WriteLine(Encoding.ASCII.GetString(responseData))
Catch webEx As WebException
if webEx.Status = WebExceptionStatus.ConnectFailure then
Console.WriteLine("Are you behind a firewall? If so, go through the proxy server.")
end if
Console.Write(webEx.ToString())
End Try
End Sub
無參數建構函式會建立 類別的新實例 WebClient 。 默認 HTTP 方法是 GET。 預設 FTP 方法是 RETR。 預設 Encoding 是 Default。
AllowAutoRedirect 的預設值為 true。
| 產品 | 版本 (已過時) |
|---|---|
| .NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5 (6, 7, 8, 9) |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| .NET Standard | 2.0, 2.1 |
