C＃从URL下载图像

Question

I use a website to get stats on wifi usage. The website creates an image of a graph representation of the data. The way it does this is by the user, setting a date. So for example, lets say it was last months statistics. The website generates a URL which is then sent to the server and the server returns an image. an examples of the link is like this:

https://www.example.com/graph/daily_usage?time_from=2015-06-01+00%3A00%3A00+%2B0100&time_to=2015-06-30+23%3A59%3A59+%2B0100&tsp=1436519988

The problem is, I am making a third party program that will download this image to be used in my program. However, I cannot use the file. It is as if the file is corrupt or something. I have tried a few methods but maybe someone can suggest a different approach. Basically, how do I download an image that is generated by a server from a URL link?

PS

Just noticed that if I download the file by right clicking through a browser and save, the image downloads with a size of 17.something kilobytes. But if I use the WebClient method to download the image, it only downloads 1.5kb. Why would that be? Seems like the WebClient method does not download completely.

Currently my code

if (hrefAtt == "Usage Graph")
{
    string url = element.getAttribute("src");
    WebClient client = new WebClient();
    client.DownloadFile(url, tempFolderPath + "\\" + currentAcc + "_UsageSummary.png");
    wd.AddImagesToDoc(tempFolderPath + "\\" + currentAcc + "_UsageSummary.png");
    wd.SaveDocument();
}

TempFolderPath is my desktop\\TempFolder\\

UPDATE Out of random, I decided to see the raw data of the file with notepad and interestingly, the image data was actually a copy of the websites homepage html code, not the raw data of the image :S how does that make sense?

Answer 1

这将下载Google徽标：

var img = Bitmap.FromStream(new MemoryStream(new WebClient().DownloadData("https://www.google.co.uk/images/srpr/logo11w.png")));

Answer 2

First of all, you have to understand link texture. If all links are same or close to each other, you have to use substring/remove/datetime etc. methods to make your new request link. For example;

string today = DateTime.Now.ToShortDateString();
string generatedLink = @"http://www.yoururl.com/image + " + today + ".jpg";
string generatedFileName = @"C:\Usage\usage + " + today + ".jpg";

WebClient wClient = new WebClient();
wClient.DownloadFile(generatedLink, generatedFileName);