同时，WebClient (万维网客户端)提供了向用URI标识的资源发送数据和从用URI标识的资源接收数据的通用方法，其中WebClient类是用URI标识的任何本地、因特网或
WebClient类使用WebRequest类提供对资源的访问。 WebClient实例可以通过在WebRequest.RegisterPrefix方法中注册的任何WebRequest子代访问数据。 缺省情况下，WebClient实例不发送可选的HTTP标头。
如果请求需要可选标头，则必须将标头添加到Headers集合中。 例如，要在响应中保留查询，必须添加用户代理标头。 此外，如果用户代理的标头丢失，服务器可能返回500 (内部服务器错误)。
在WebClient实例中，AllowAutoRedirect设置为true。
看一下webclient在MSND上的解释，有上传和下载的方法。
WebClient提供以下上载方法：
WebClient提供以下下载方法：
二、WebClient与其他网络相关类的区别WebClient和HttpWebRequst是获取数据的两种方式，一般来说，WebClient倾向于“按需下载”，实际掌握它
后者类似于form的submit。 虽然这两个请求都是异步请求事件，但WebClient是基于事件的异步，而HttpWebRequst是基于代理的异步编程。
三. WebClient使用样例文件下载：
protectedvoidbutton1_ click (object sender，EventArgs e ) string URL=' http://localhost/sprayer web/download/1.zip ' WIP ' byte [ ] bytes=webclient.download data (URL； string path=string.format (({0}{1}) {2}、server.mappath )、((download )、datetime filestream fs fs.write(bytes，0，bytes.Length )； fs.Close (； } protectedvoidbutton2_ click (object sender，EventArgs e ) webclient webclient=new webclient )； string URL=' http://localhost/sprayer web/download/1.zip '； streamstream=webclient.openread (URL； string path=string.format (({0}{1}) {2}、server.mappath )、((download )、datetime filestream fs byte[] bytes=new byte[8192]； int read=0； while((read=stream.read ) bytes，0，bytes.Length ) )0) {fs.write ) bytes，0，read； //此处需要read，bytes.Length } fs.Close )； } protectedvoidbutton3_ click (object sender，EventArgs e ) webclient webclient=new webclient )； string URL=' http://localhost/sprayer web/download/1.zip '； string path=string.Format
("{0}\{1}\{2}{3}", Server.MapPath("~"), "download", DateTime.Now.ToString("yyyyHHmmHHmmssfff"), ".zip"); webclient.DownloadFile(url, path); } protected void Button4_Click(object sender, EventArgs e) { String url = "http://localhost/SprayerWeb/download/1.zip"; Uri uri = new Uri(url, UriKind.Absolute); WebClient webclient = new WebClient(); webclient.OpenReadAsync(uri); webclient.OpenReadCompleted+=webclient_OpenReadCompleted; } private void webclient_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e) { Stream stream = e.Result; byte[] bytes = new byte[8192]; int read = 0; string path = string.Format("{0}\{1}\{2}{3}", Server.MapPath("~"), "download", DateTime.Now.ToString("yyyyHHmmHHmmssfff"), ".zip"); FileStream fs = new FileStream(path, FileMode.Create); while ((read = stream.Read(bytes, 0, bytes.Length)) > 0) { fs.Write(bytes, 0, read); } fs.Close(); stream.Close(); }文件上传：
protected void Button5_Click(object sender, EventArgs e) { //在IIS6下没有执行成功，以后再调试吧 WebClient webclient = new WebClient(); string targetpath = string.Format("{0}{1}{2}","http://localhost/WebApp/upload/",DateTime.Now.ToString("yyyyMMddHHmmssfff"),".zip"); string sourcepath = string.Format("{0}\{1}\{2}{3}", Server.MapPath("~"), "download", "1", ".zip"); byte[] responseArray = webclient.UploadFile(targetpath, "PUT", sourcepath); } protected void Button6_Click(object sender, EventArgs e) { //在IIS6下没有执行成功，以后再调试吧 string targetpath = string.Format("{0}{1}{2}", "http://localhost/WebApp/upload/", DateTime.Now.ToString("yyyyMMddHHmmssfff"), ".zip"); string sourcepath = string.Format("{0}\{1}\{2}{3}", Server.MapPath("~"), "download", "1", ".zip"); WebClient webclient = new WebClient(); FileStream fs = new FileStream(sourcepath, FileMode.Open, FileAccess.Read); byte[] bt = new byte[fs.Length]; fs.Read(bt, 0, bt.Length); byte[] responseArray = webclient.UploadData(targetpath, "PUT", bt); fs.Close(); } protected void Button7_Click(object sender, EventArgs e) { WebClient webclient = new WebClient(); string sourcepath = string.Format("{0}\{1}\{2}{3}", Server.MapPath("~"), "download", "1", ".zip"); byte[] responseArray= webclient.UploadFile("http://localhost/WebApp/upload.aspx", "POST", sourcepath); Response.Write("result:"+System.Text.Encoding.UTF8.GetString(responseArray)); }
upload.aspx文件代码如下：
protected void Page_Load(object sender, EventArgs e) { //string uploadpath = string.Format("{0}\{1}{}"); foreach (string f in Request.Files.AllKeys) { HttpPostedFile postfile = Request.Files[f]; string path = String.Format("{0}\{1}\{2}{3}",Server.MapPath("~"),"upload",DateTime.Now.Ticks.ToString(),".zip"); postfile.SaveAs(path); } Response.Write("Success"); }
更多详细内容参考:https://msdn.microsoft.com/zh-cn/library/system.net.webclient%28VS.80%29.aspx