如何从互联网上读取文件？
简单问题：我有一个在线文件（txt）。 如何阅读并检查它是否存在？ （C＃.net 2.0）
来自http://www.csharp-station.com/HowTo/HttpWebFetch.aspx
HttpWebRequest request = (HttpWebRequest) WebRequest.Create("myurl"); // execute the request HttpWebResponse response = (HttpWebResponse) request.GetResponse(); // we will read data via the response stream Stream resStream = response.GetResponseStream(); string tempString = null; int count = 0; do { // fill the buffer with data count = resStream.Read(buf, 0, buf.Length); // make sure we read some data if (count != 0) { // translate from bytes to ASCII text tempString = Encoding.ASCII.GetString(buf, 0, count); // continue building the string sb.Append(tempString); } } while (count > 0); // any more data to read? // print out page source Console.WriteLine(sb.ToString()); 我认为WebClient类适合于此：
WebClient client = new WebClient(); Stream stream = client.OpenRead("http://yoururl/test.txt"); StreamReader reader = new StreamReader(stream); String content = reader.ReadToEnd();
http://msdn.microsoft.com/en-us/library/system.net.webclient.openread.aspx
首先，您可以下载二进制文件：
public byte[] GetFileViaHttp(string url) { using (WebClient client = new WebClient()) { return client.DownloadData(url); } }
然后你可以为文本文件创建字符串数组（假设UTF-8并且它是一个文本文件）：
var result = GetFileViaHttp(@"http://example.com/index.html"); string str = Encoding.UTF8.GetString(result); string[] strArr = str.Split(new[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries);
您将在每个数组字段中收到每个（除空）文本行。
一点点简单的方法：
string fileContent = new WebClient().DownloadString("yourURL");
WebClient是HttpWebRequest的替代品
// create a new instance of WebClient WebClient client = new WebClient(); // set the user agent to IE6 client.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.0.3705;)"); try { // actually execute the GET request string ret = client.DownloadString("http://www.google.com/"); // ret now contains the contents of the webpage Console.WriteLine("First 256 bytes of response: " + ret.Substring(0,265)); } catch (WebException we) { // WebException.Status holds useful information Console.WriteLine(we.Message + "\n" + we.Status.ToString()); } catch (NotSupportedException ne) { // other errors Console.WriteLine(ne.Message); }
示例来自http://www.daveamenta.com/2008-05/c-webclient-usage/
查看System.Net.WebClient ，文档甚至有一个检索文件的示例。
但是测试文件是否存在意味着要求该文件并捕获exception（如果它不存在）。