对于web下的上传，实际上更多的时候不用上传太大东西，asp.net默认的上传组件足够用了，美中不足就是没有上传进度反映，所以现在要做的就是在asp.net默认的上传基础上加上进度反映。
关于web上传的原理，曾在以前有深入分析过《asp无组件上传进度条解决方案》《Asp无组件上传带进度条(续) 》，并有写过asp版的无组件上传进度条，在这里就不多赘述。相信很多人都看过思归发的《用ASP.NET上传大文件》，解决的方法是利用隐含的HttpWorkerRequest，用它的GetPreloadedEntityBody 和 ReadEntityBody方法从IIS为ASP.NET建立的pipe里分块读取数据，对于每块分块进行分析并存储为临时文件，相对比较复杂。
要实现进度条的实时反映，核心的技术就是对上传的数据进行“分块”读取，在读取每块数据时记录当前已上传的块数，根据分块的大小，即可知道已上传的大小，根据总大小，即可知道当前上传的进度。具体的技术还是利用隐含的HttpWorkerRequest，用它的GetPreloadedEntityBody 和 ReadEntityBody方法从IIS为ASP.NET建立的pipe里分块读取数据，只不过仅仅是分块和记录已上传块数而已，用不着对已上传的数据进行分析和处理，因为这部分复杂的工作已经由asp.net的上传组件给我们做了。
根据上面所述的原理，具体代码相对很简单，我写了一个例子，用一个专门的进度显示页面(Progress.aspx)，通过定时刷新(XmlHttp, FF支持)来获取当前上传的进度信息，并实时反映到上传页面上。
代码下载（解压后给web目录设置虚拟目录为“Upload”即可），其中进度条我是用脚本来实现的，单独的进度条脚本代码：http://www.webuc.net/myproject/progressbar/progressinfo.htm http://www.webuc.net/myproject/progressbar/progressbar.rar
using System; using System.Collections; using System.Collections.Specialized; using System.Globalization; using System.IO; using System.Text; using System.Web; using System.Reflection; namespace Openlab.Web.Upload { /// <summary> /// 给asp.net默认的上传组件加上进度条反映 /// </summary> /// <Author>宝玉 (http://www.webuc.net)</Author> /// <Links> /// http://www.cnforums.net /// http://www.communtiyserver.cn /// http://blog.joycode.com /// </Links> public class HttpUploadModule: IHttpModule { public HttpUploadModule() { } public void Init(HttpApplication application) { application.BeginRequest += new EventHandler(this.Application_BeginRequest); application.EndRequest += new EventHandler(this.Application_EndRequest); application.Error += new EventHandler(this.Application_Error); } public void Dispose() { } private void Application_BeginRequest(Object sender, EventArgs e) { HttpApplication app = sender as HttpApplication; HttpWorkerRequest request = GetWorkerRequest(app.Context); Encoding encoding = app.Context.Request.ContentEncoding; int bytesRead = 0; // 已读数据大小 int read; // 当前读取的块的大小 int count = 8192; // 分块大小 byte[] buffer; // 保存所有上传的数据 string uploadId; // 唯一标志当前上传的ID Progress progress; // 记录当前上传的进度信息 if (request != null) { // 返回 HTTP 请求正文已被读取的部分。 // byte[] tempBuff = request.GetPreloadedEntityBody(); // 如果是附件上传 // if ( tempBuff != null && IsUploadRequest(app.Request) ) { // 获取上传大小 // long length = long.Parse(request.GetKnownRequestHeader(HttpWorkerRequest.HeaderContentLength)); // 当前上传的ID，用来唯一标志当前的上传 // 用此UploadID，可以通过其他页面获取当前上传的进度 // uploadId = app.Context.Request.QueryString["UploadID"]; // 开始记录当前上传状态 // progress = new Progress(length, uploadId); progress.SetState(UploadState.ReceivingData); buffer = new byte[length]; count = tempBuff.Length; // 分块大小 // 将已上传数据复制过去 // Buffer.BlockCopy(tempBuff, 0, buffer, bytesRead, count); // 开始记录已上传大小 // bytesRead = tempBuff.Length; progress.SetBytesRead(bytesRead); SetProgress(uploadId, progress, app.Application); // 循环分块读取，直到所有数据读取结束 // while (request.IsClientConnected() && !request.IsEntireEntityBodyIsPreloaded() && bytesRead < length ) { // 如果最后一块大小小于分块大小，则重新分块 // if (bytesRead + count > length) { count = (int)(length - bytesRead); tempBuff = new byte[count]; } // 分块读取 // read = request.ReadEntityBody(tempBuff, count); // 复制已读数据块 // Buffer.BlockCopy(tempBuff, 0, buffer, bytesRead, read); // 记录已上传大小 // bytesRead += read; progress.SetBytesRead(bytesRead); SetProgress(uploadId, progress, app.Application); } if ( request.IsClientConnected() && !request.IsEntireEntityBodyIsPreloaded() ) { // 传入已上传完的数据 // InjectTextParts(request, buffer); // 表示上传已结束 // progress.SetBytesRead(bytesRead); progress.SetState(UploadState.Complete); SetProgress(uploadId, progress, app.Application); } } } } /// <summary> /// 结束请求后移除进度信息 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private void Application_EndRequest(Object sender, EventArgs e) { HttpApplication app = sender as HttpApplication; if (IsUploadRequest(app.Request)) { SetUploadState(app, UploadState.Complete); RemoveFrom(app); } } /// <summary> /// 如果出错了设置进度信息中状态为“Error” /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private void Application_Error(Object sender, EventArgs e) { HttpApplication app = sender as HttpApplication; if (IsUploadRequest(app.Request)) { SetUploadState(app, UploadState.Error); } } /// <summary> /// 设置当前上传进度信息的状态 /// </summary> /// <param name="app"></param> /// <param name="state"></param> void SetUploadState(HttpApplication app, UploadState state) { string uploadId = app.Request.QueryString["UploadID"]; if (uploadId != null && uploadId.Length > 0) { Progress progress = GetProgress(uploadId, app.Application); if (progress != null) { progress.SetState(state); SetProgress(uploadId, progress, app.Application); } } } /// <summary> /// 设置当前上传的进度信息 /// 根据UploadID记录在Application中 /// </summary> /// <param name="uploadId"></param> /// <param name="progress"></param> /// <param name="application"></param> void SetProgress(string uploadId, Progress progress, HttpApplicationState application) { if (uploadId == null || uploadId == string.Empty || progress == null) return; application.Lock(); application["OpenlabUpload_" + uploadId] = progress; application.UnLock(); } /// <summary> /// 从Application中移出进度信息 /// </summary> /// <param name="app"></param> void RemoveFrom(HttpApplication app) { string uploadId = app.Request.QueryString["UploadID"]; HttpApplicationState application = app.Application; if (uploadId != null && uploadId.Length > 0) { application.Remove("OpenlabUpload_" + uploadId); } } /// <summary> /// 根据UploadID获取上传进度信息 /// </summary> /// <param name="uploadId"></param> /// <param name="application"></param> /// <returns></returns> public static Progress GetProgress(string uploadId, HttpApplicationState application) { Progress progress = application["OpenlabUpload_" + uploadId] as Progress; return progress; } HttpWorkerRequest GetWorkerRequest(HttpContext context) { IServiceProvider provider = (IServiceProvider)HttpContext.Current; return (HttpWorkerRequest)provider.GetService(typeof(HttpWorkerRequest)); } /// <summary> /// 传入已上传完的数据 /// </summary> /// <param name="request"></param> /// <param name="textParts"></param> void InjectTextParts(HttpWorkerRequest request, byte[] textParts) { BindingFlags bindingFlags = BindingFlags.Instance | BindingFlags.NonPublic; Type type = request.GetType(); while ((type != null) && (type.FullName != "System.Web.Hosting.ISAPIWorkerRequest")) { type = type.BaseType; } if (type != null) { type.GetField("_contentAvailLength", bindingFlags).SetValue(request, textParts.Length); type.GetField("_contentTotalLength", bindingFlags).SetValue(request, textParts.Length); type.GetField("_preloadedContent", bindingFlags).SetValue(request, textParts); type.GetField("_preloadedContentRead", bindingFlags).SetValue(request, true); } } private static bool StringStartsWithAnotherIgnoreCase(string s1, string s2) { return (string.Compare(s1, 0, s2, 0, s2.Length, true, CultureInfo.InvariantCulture) == 0); } /// <summary> /// 是否为附件上传 /// 判断的根据是ContentType中有无multipart/form-data /// </summary> /// <param name="request"></param> /// <returns></returns> bool IsUploadRequest(HttpRequest request) { return StringStartsWithAnotherIgnoreCase(request.ContentType, "multipart/form-data"); } } }
转载于:https://www.cnblogs.com/feima-lxl/archive/2008/07/12/1241256.html
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