HttpListener.GetContext Method

Reference

Definition

Namespace:: System.Net

Assemblies:: netstandard.dll, System.Net.HttpListener.dll

Assembly:: System.Net.HttpListener.dll

Assembly:: System.dll

Assembly:: netstandard.dll

Source:: HttpListener.Managed.cs

Source:: HttpListener.Managed.cs

Source:: HttpListener.Managed.cs

Important

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Waits for an incoming request and returns when one is received.

public:
 System::Net::HttpListenerContext ^ GetContext();

public System.Net.HttpListenerContext GetContext();

member this.GetContext : unit -> System.Net.HttpListenerContext

Public Function GetContext () As HttpListenerContext

Returns

HttpListenerContext

An HttpListenerContext object that represents a client request.

Exceptions

HttpListenerException

A Win32 function call failed. Check the exception's ErrorCode property to determine the cause of the exception.

InvalidOperationException

This object has not been started or is currently stopped.

-or-

The HttpListener does not have any Uniform Resource Identifier (URI) prefixes to respond to.

ObjectDisposedException

This object is closed.

Examples

The following code example demonstrates calling this method.

// This example requires the System and System.Net namespaces.
public static void SimpleListenerExample(string[] prefixes)
{
    if (!HttpListener.IsSupported)
    {
        Console.WriteLine ("Windows XP SP2 or Server 2003 is required to use the HttpListener class.");
        return;
    }
    // URI prefixes are required,
    // for example "http://contoso.com:8080/index/".
    if (prefixes == null || prefixes.Length == 0)
      throw new ArgumentException("prefixes");

    // Create a listener.
    HttpListener listener = new HttpListener();
    // Add the prefixes.
    foreach (string s in prefixes)
    {
        listener.Prefixes.Add(s);
    }
    listener.Start();
    Console.WriteLine("Listening...");
    // Note: The GetContext method blocks while waiting for a request.
    HttpListenerContext context = listener.GetContext();
    HttpListenerRequest request = context.Request;
    // Obtain a response object.
    HttpListenerResponse response = context.Response;
    // Construct a response.
    string responseString = "<HTML><BODY> Hello world!</BODY></HTML>";
    byte[] buffer = System.Text.Encoding.UTF8.GetBytes(responseString);
    // Get a response stream and write the response to it.
    response.ContentLength64 = buffer.Length;
    System.IO.Stream output = response.OutputStream;
    output.Write(buffer,0,buffer.Length);
    // You must close the output stream.
    output.Close();
    listener.Stop();
}

Public Shared Sub SimpleListenerExample(prefixes As String())
    If Not HttpListener.IsSupported Then
        Console.WriteLine("Windows XP SP2 or Server 2003 is required to use the HttpListener class.")
        Return
    End If
    ' URI prefixes are required,
    ' for example "http://contoso.com:8080/index/".
    If prefixes Is Nothing Or prefixes.Length = 0 Then
        Throw New ArgumentException("prefixes")
    End If

    ' Create a listener
    Dim listener = New HttpListener()

    For Each s As String In prefixes
        listener.Prefixes.Add(s)
    Next
    listener.Start()
    Console.WriteLine("Listening...")
    ' Note: The GetContext method blocks while waiting for a request.
    Dim context As HttpListenerContext = listener.GetContext()
    Console.WriteLine("Listening...")
    ' Obtain a response object
    Dim request As HttpListenerRequest = context.Request
    ' Construct a response.
    Dim response As HttpListenerResponse = context.Response
    Dim responseString As String = "<HTML><BODY> Hello world!</BODY></HTML>"
    Dim buffer As Byte() = System.Text.Encoding.UTF8.GetBytes(responseString)
    ' Get a response stream and write the response to it.
    response.ContentLength64 = buffer.Length
    Dim output As System.IO.Stream = response.OutputStream
    output.Write(buffer, 0, buffer.Length)
    'You must close the output stream.
    output.Close()
    listener.Stop()
End Sub

Remarks

Before calling this method, you must call the Start method and add at least one URI prefix to listen for by adding the URI strings to the HttpListenerPrefixCollection returned by the Prefixes property. For a detailed description of prefixes, see the HttpListener class overview.

This method blocks while waiting for an incoming request. If you want incoming requests to be processed asynchronously (on separate threads) so that your application does not block, use the BeginGetContext method.

Notes to Callers

This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing in the .NET Framework.

Applies to

Product	Versions
.NET	Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10
.NET Framework	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

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