前前提：C/S
前提：需要引用System.Net.dll

///<summary>
/// 下载文件
/// </summary>
/// <param name="URL">下载文件地址</param>
/// <param name="Filename">下载后另存为（全路径）</param>
private bool DownloadFile(string URL, string filename)
{
try
{
HttpWebRequest Myrq = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(URL);
HttpWebResponse myrp = (System.Net.HttpWebResponse)Myrq.GetResponse();
Stream st = myrp.GetResponseStream();
Stream so = new System.IO.FileStream(filename, System.IO.FileMode.Create);
byte[] by = new byte[1024];
int osize = st.Read(by, 0, (int)by.Length);
while (osize > 0)
{
so.Write(by, 0, osize);
osize = st.Read(by, 0, (int)by.Length);
}
so.Close();
st.Close();
myrp.Close();
Myrq.Abort();
return true;
}
catch (System.Exception e)
{
return false
}
}