C＃中System.Net的Webclient无法连接到服务器

Question

Is there something I need to do to get System.Net working with Microsoft Visual C# 2008 Express Edition? I can't seem to get any web type controls or classes to work at all.. the below WebClient example always throws the exception " Unable to connect to the remote server ".. and consequently I can't get the WebBrowser control to load a page either.

Here is the code (Edited):

using System;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Net;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            using (WebClient client = new WebClient()) {
                string s = client.DownloadString("http://www.google.com");
                this.textBox1.Text = s;
            }
        }
    }
}

This is in a simple form with only a textbox control (with multiline set to true) in it. The exception gets thrown on the DownloadString(...) line. I also tried using WebRequest .. same exception!

EDIT:

I am connected to a Linksys WRT54G Router that connects directly to my cable modem. I am not behind a proxy server, although I did run proxycfg -u and I got:

Updated proxy settings
Current WinHTTP proxy settings under:
  HKEY_LOCAL_MACHINE\
    SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Connections\
      WinHttpSettings :

 Direct access (no proxy server).

I am using Windows XP and not running any kind of firewall. Only AVG at the moment. I'm pretty sure I shouldn't have to forward any ports or anything, but I did try forwarding port 80 to my workstation on my router. Didn't help.

Answer 1

( update - I meant proxycfg , not httpcfg ; proxycfg -u will do the import)

First, there is nothing special about "express" here. Second, contoso is a dummy url.

What OS are you on? And do you go through a proxy server? If so, you might need to configure the OS's http stack - proxycfg will do the job on XP, and can be used to import the user's IE settings.

The sample is fine, although it doesn't correctly handle the multiple IDisposable objects - the following is much simpler:

        using (WebClient client = new WebClient()) {
            string s = client.DownloadString("http://www.google.com");
            // do something with s
        }

Answer 2

Do you have any firewall software on your PC that might be affecting it? Have you tried with any sites other than Google?