我从网站下载图像。这是代码：
class MyClient : WebClient
{
public bool HeadOnly { get; set; }
protected override WebRequest GetWebRequest(Uri address)
{
WebRequest req = base.GetWebRequest(address);
if (HeadOnly && req.Method == "GET")
{
req.Method = "HEAD";
}
return req;
}
}
然后方法：
public static HtmlAgilityPack.HtmlDocument getHtmlDocumentWebClient(string url, bool useProxy, string proxyIp, int proxyPort, string usename, string password)
{
HtmlAgilityPack.HtmlDocument doc = null;
try
{
doc = null;
using (MyClient clients = new MyClient())
{
clients.HeadOnly = true;
byte[] body = clients.DownloadData(url);
// note should be 0-length
string type = clients.ResponseHeaders["content-type"];
clients.HeadOnly = false;
// check 'tis not binary... we'll use text/, but could
// check for text/html
if (type == null)
{
return null;
}
else
{
if (type.StartsWith(@"text/html"))
{
string text = clients.DownloadString(url);
try
{
doc = new HtmlAgilityPack.HtmlDocument();
WebClient client = new WebClient();
//client.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");
client.Credentials = CredentialCache.DefaultCredentials;
client.Proxy = WebRequest.DefaultWebProxy;
if (useProxy)
{
//Proxy
if (!string.IsNullOrEmpty(proxyIp))
{
WebProxy p = new WebProxy(proxyIp, proxyPort);
if (!string.IsNullOrEmpty(usename))
{
if (password == null)
password = string.Empty;
NetworkCredential nc = new NetworkCredential(usename, password);
p.Credentials = nc;
}
}
}
doc.Load(client.OpenRead(url));
}
catch
{
}
}
}
}
if (doc == null)
{
MessageBox.Show("Doc is null " + doc + " The link that did it was " + url);
}
}
catch
{
}
return doc;
}
我尝试向该方法添加一般尝试捕获，但它仍然到达 MessageBox 而不是捕获。
无论如何，我试图下载的图像的链接是：
http://members.tripod.com/~DannyWest/bundy.jpg
然后我使用了断点 t 并上线：
if (type.StartsWith(@"text/html"))
它跳到 MessageBox.Show...
现在我看到该类型包含：image/jpeg 我想知道这是否是问题，因为没有 text/html 或其他可能有链接的东西？
编辑**
我试图改变添加这个的方法：
if (type.StartsWith(@"text/html")|| type.StartsWith(@"image/jpeg"))
添加了部分 image/jpeg 但随后它在另一个类上使用了此方法：
private List<string> getLinks(HtmlAgilityPack.HtmlDocument document)
{
List<string> mainLinks = new List<string>();
var linkNodes = document.DocumentNode.SelectNodes("//a[@href]");
if (linkNodes != null)
{
foreach (HtmlNode link in linkNodes)
{
var href = link.Attributes["href"].Value;
if (href.StartsWith("http://") == true || href.StartsWith("https://") == true || href.StartsWith("www") == true) // filter for http
{
mainLinks.Add(href);
}
}
}
return mainLinks;
}
并且 linkNodes 一直为空。当 type.StartsWith 为 image/jpeg 时，此 linkNodes 始终为空。当 type.StartsWith 为 text/html 时， linkNodes 不为空。
如果需要，我可以将我的项目上传到我的 Skydrive。