需要引入命名空间：
代码如下：

using System.Net;
using System.IO;

函数内容：
代码如下：

/// <summary>
/// 根据Url获得源文件内容
/// </summary>
/// <param name="url">合法的Url地址</param>
/// <returns></returns>
public static string GetSourceTextByUrl(string url)
{
WebRequest request = WebRequest.Create(url);
request.Timeout = 20000;//20秒超时
WebResponse response = request.GetResponse();

Stream resStream = response.GetResponseStream();
StreamReader sr = new StreamReader(resStream);
return sr.ReadToEnd();
}