网页内容读取三种方法的区别[未完]

//WebClient
public static string GetPageContentByWebClient(string url)
{
string content = string.Empty;
try
{
WebClient client = new WebClient();
client.Credentials = CredentialCache.DefaultCredentials;
byte[] buffer = client.DownloadData(url);
content = Encoding.Default.GetString(buffer);
}
catch (WebException ex)
{

}
return content;
}

//WebBrowser
public static string GetPageContentByWebBrowser(string url)
{
StringBuilder content = new StringBuilder();
try
{
WebBrowser browser = new WebBrowser();
browser.Navigate(url);
browser.DocumentCompleted += delegate
{
HtmlElementCollection elts = browser.Document.GetElementsByTagName("html");
foreach (HtmlElement elt in elts)
{
content.Append(elt.OuterHtml);
break;
}
};
}
catch (WebException ex)
{

}
return content.ToString();
}

//WebRequest/WebResponse
public static string GetPageContentByWebRequestResponse(string url)
{
string content = string.Empty;
try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
using (Stream stream = response.GetResponseStream())
{
using (StreamReader reader = new StreamReader(stream,Encoding.Default))
{
content = reader.ReadToEnd();
response.Close();
}
}
}
}
catch (WebException ex)
{

}
return content.ToString();
}