WebClient.DownloadString不返回任何数据

Question

I'm experiencing a strange issue with WebClient.DownloadString that I can't seem to solve, my code:

Dim client As New WebClient()
Dim html = client.DownloadString("http://www.btctrade.com/")

The content doesn't seem to be fully AJAX, so it can't be that. Is it due to the web page being in Chinese? I'm guessing HTML is just served as HTML, so can't really be that either. The URL is fine when I go to it and there seems to be no redirects to https either.

Anyone know why this is happening?

Answer 1

You must set cookies and useragent in the webclient headers this works

client .Headers.Add(HttpRequestHeader.UserAgent, "UserAgent,Mozilla/5.0 (Windows NT 5.1; rv:14.0) Gecko/20100101 Firefox/14.0.1");
client .Headers.Add(HttpRequestHeader.Cookie, "USER_PW=9b1283bfe37ac47b243a1e0c9c1c9e52; PHPSESSID=f692406a0c84dba2605a7065d55a3b53")

and if u want that the request do all this work , you have to user httpwebrequest then save all the response's headers and use them in a new request

Answer 2

WebClient is not buggy, so probably the server is returning data you did not expect. Use Fiddler to watch what happens when you go to the site in a web browser.

When I executed your code the web site returned no data. When I visited the site in a web browser it returned data. Probably, the site is detecting that you are a bot and denying you access. Fake being a browser by mimicking what you see in Fiddler.