怎样在asp.net中用一般处理文件ashx实现下载功能

John_Smith 发布于 2011/07/15 11:15
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我通过ajax将文件的完整名称作为参数传入到ashx处理文件中,现在想通过这个一般处理文件,将传入的文件下载下来,这个该怎么实现?

现在客户端js代码如下:

$.post("ajax/DownloadFileHandler.ashx",{"filePath":filePath},function(data,status){});

ajax回调函数没有进行任何操作,filePath就是传入的文件完整路径名称,DownloadFileHandler.ashx中要处理filePath这个文件的下载功能,

在DownloadFileHandler.ashx中应该怎么写?


最好贴上代码
非常感谢!!!

加载中
0
笨蛋EGG
笨蛋EGG

正在用的······我也是抄网上的·····

        /// <summary>
          /// 下载文件,支持大文件、续传、速度限制。支持续传的响应头Accept-Ranges、ETag,请求头Range 。
          /// Accept-Ranges:响应头,向客户端指明,此进程支持可恢复下载.实现后台智能传输服务(BITS),值为:bytes;
          /// ETag:响应头,用于对客户端的初始(200)响应,以及来自客户端的恢复请求,
          /// 必须为每个文件提供一个唯一的ETag值(可由文件名和文件最后被修改的日期组成),这使客户端软件能够验证它们已经下载的字节块是否仍然是最新的。
          /// Range:续传的起始位置,即已经下载到客户端的字节数,值如:bytes=1474560- 。
          /// 另外:UrlEncode编码后会把文件名中的空格转换中+(+转换为%2b),但是浏览器是不能理解加号为空格的,所以在浏览器下载得到的文件,空格就变成了加号;
          /// 解决办法:UrlEncode 之后, 将 "+" 替换成 "%20",因为浏览器将%20转换为空格
         /// </summary>
         /// <param name="httpContext">当前请求的HttpContext</param>
         /// <param name="filePath">下载文件的物理路径,含路径、文件名</param>
         /// <param name="speed">下载速度:每秒允许下载的字节数</param>
         /// <returns>true下载成功,false下载失败</returns>
        public static bool DownloadFile(HttpContext httpContext, string filePath, long speed)
        {
            httpContext.Response.Clear();
            bool ret = true;
            try
            {
                #region --验证:HttpMethod,请求的文件是否存在#region
                switch (httpContext.Request.HttpMethod.ToUpper())
                { //目前只支持GET和HEAD方法
                    case "GET":
                    case "HEAD":
                        break;
                    default:
                        httpContext.Response.StatusCode = 501;
                        return false;
                }
                if (!File.Exists(filePath))
                {
                    httpContext.Response.StatusCode = 404;
                    return false;
                }
                #endregion

                #region 定义局部变量#region 定义局部变量
                long startBytes = 0;
                long stopBytes = 0;
                int packSize = 1024 * 10; //分块读取,每块10K bytes
                string fileName = Path.GetFileName(filePath);
                FileStream myFile = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
                BinaryReader br = new BinaryReader(myFile);
                long fileLength = myFile.Length;

                int sleep = (int)Math.Ceiling(1000.0 * packSize / speed);//毫秒数:读取下一数据块的时间间隔
                string lastUpdateTiemStr = File.GetLastWriteTimeUtc(filePath).ToString("r");
                string eTag = HttpUtility.UrlEncode(fileName, Encoding.UTF8) + lastUpdateTiemStr;//便于恢复下载时提取请求头;
                #endregion

                #region --验证:文件是否太大,是否是续传,且在上次被请求的日期之后是否被修改过
                if (myFile.Length > long.MaxValue)
                {//-------文件太大了-------
                    httpContext.Response.StatusCode = 413;//请求实体太大
                    return false;
                }

                if (httpContext.Request.Headers["If-Range"] != null)//对应响应头ETag:文件名+文件最后修改时间
                {
                    //----------上次被请求的日期之后被修改过--------------
                    if (httpContext.Request.Headers["If-Range"].Replace("\"", "") != eTag)
                    {//文件修改过
                        httpContext.Response.StatusCode = 412;//预处理失败
                        return false;
                    }
                }
                #endregion

                try
                {
                    #region -------添加重要响应头、解析请求头、相关验证
                    httpContext.Response.Clear();

                    if (httpContext.Request.Headers["Range"] != null)
                    {//------如果是续传请求,则获取续传的起始位置,即已经下载到客户端的字节数------
                        httpContext.Response.StatusCode = 206;//重要:续传必须,表示局部范围响应。初始下载时默认为200
                        string[] range = httpContext.Request.Headers["Range"].Split(new char[] { '=', '-' });//"bytes=1474560-"
                        startBytes = Convert.ToInt64(range[1]);//已经下载的字节数,即本次下载的开始位置  
                        if (startBytes < 0 || startBytes >= fileLength)
                        {//无效的起始位置
                            return false;
                        }
                        if (range.Length == 3)
                        {
                            stopBytes = Convert.ToInt64(range[2]);//结束下载的字节数,即本次下载的结束位置  
                            if (startBytes < 0 || startBytes >= fileLength)
                            {
                                return false;
                            }
                        }
                    }

                    httpContext.Response.Buffer = false;
                    httpContext.Response.AddHeader("Content-MD5", My_Des.MD5JiaMi_File(filePath));//用于验证文件
                    httpContext.Response.AddHeader("Accept-Ranges", "bytes");//重要:续传必须
                    httpContext.Response.AppendHeader("ETag", "\"" + eTag + "\"");//重要:续传必须
                    httpContext.Response.AppendHeader("Last-Modified", lastUpdateTiemStr);//把最后修改日期写入响应                
                    httpContext.Response.ContentType = "application/octet-stream";//MIME类型:匹配任意文件类型
                    httpContext.Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(fileName, Encoding.UTF8).Replace("+", "%20"));
                    httpContext.Response.AddHeader("Content-Length", (fileLength - startBytes).ToString());
                    httpContext.Response.AddHeader("Connection", "Keep-Alive");
                    httpContext.Response.ContentEncoding = Encoding.UTF8;
                    if (startBytes > 0)
                    {//------如果是续传请求,告诉客户端本次的开始字节数,总长度,以便客户端将续传数据追加到startBytes位置后----------
                        httpContext.Response.AddHeader("Content-Range", string.Format("bytes {0}-{1}/{2}", startBytes, fileLength - 1, fileLength));
                    }
                    #endregion

                    #region -------向客户端发送数据块-------------------
                    br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
                    int maxCount = (int)Math.Ceiling((fileLength - startBytes + 0.0) / packSize);//分块下载,剩余部分可分成的块数
                    for (int i = 0; i < maxCount && httpContext.Response.IsClientConnected; i++)
                    {//客户端中断连接,则暂停
                        httpContext.Response.BinaryWrite(br.ReadBytes(packSize));
                        httpContext.Response.Flush();
                        if (sleep > 1) Thread.Sleep(sleep);
                    }
                    #endregion
                }
                catch
                {
                    ret = false;
                }
                finally
                {
                    br.Close();
                    myFile.Close();
                }
            }
            catch
            {
                ret = false;
            }
            return ret;
        }
0
笨蛋EGG
笨蛋EGG

貌似不会自动换行?!

在DownloadFileHandler.ashx调用就好了···

0
笨蛋EGG
笨蛋EGG

        再发一个没有放在代码框里的····

 

 

/// <summary>

          /// 下载文件,支持大文件、续传、速度限制。支持续传的响应头Accept-Ranges、ETag,请求头Range 。
          /// Accept-Ranges:响应头,向客户端指明,此进程支持可恢复下载.实现后台智能传输服务(BITS),值为:bytes;
          /// ETag:响应头,用于对客户端的初始(200)响应,以及来自客户端的恢复请求,
          /// 必须为每个文件提供一个唯一的ETag值(可由文件名和文件最后被修改的日期组成),这使客户端软件能够验证它们已经下载的字节块是否仍然是最新的。
          /// Range:续传的起始位置,即已经下载到客户端的字节数,值如:bytes=1474560- 。
          /// 另外:UrlEncode编码后会把文件名中的空格转换中+(+转换为%2b),但是浏览器是不能理解加号为空格的,所以在浏览器下载得到的文件,空格就变成了加号;
          /// 解决办法:UrlEncode 之后, 将 "+" 替换成 "%20",因为浏览器将%20转换为空格
         /// </summary>
         /// <param name="httpContext">当前请求的HttpContext</param>
         /// <param name="filePath">下载文件的物理路径,含路径、文件名</param>
         /// <param name="speed">下载速度:每秒允许下载的字节数</param>
         /// <returns>true下载成功,false下载失败</returns>
        public static bool DownloadFile(HttpContext httpContext, string filePath, long speed)
        {
            httpContext.Response.Clear();
            bool ret = true;
            try
            {
                #region --验证:HttpMethod,请求的文件是否存在#region
                switch (httpContext.Request.HttpMethod.ToUpper())
                { //目前只支持GET和HEAD方法
                    case "GET":
                    case "HEAD":
                        break;
                    default:
                        httpContext.Response.StatusCode = 501;
                        return false;
                }
                if (!File.Exists(filePath))
                {
                    httpContext.Response.StatusCode = 404;
                    return false;
                }
                #endregion

                #region 定义局部变量#region 定义局部变量
                long startBytes = 0;
                long stopBytes = 0;
                int packSize = 1024 * 10; //分块读取,每块10K bytes
                string fileName = Path.GetFileName(filePath);
                FileStream myFile = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
                BinaryReader br = new BinaryReader(myFile);
                long fileLength = myFile.Length;

                int sleep = (int)Math.Ceiling(1000.0 * packSize / speed);//毫秒数:读取下一数据块的时间间隔
                string lastUpdateTiemStr = File.GetLastWriteTimeUtc(filePath).ToString("r");
                string eTag = HttpUtility.UrlEncode(fileName, Encoding.UTF8) + lastUpdateTiemStr;//便于恢复下载时提取请求头;
                #endregion

                #region --验证:文件是否太大,是否是续传,且在上次被请求的日期之后是否被修改过
                if (myFile.Length > long.MaxValue)
                {//-------文件太大了-------
                    httpContext.Response.StatusCode = 413;//请求实体太大
                    return false;
                }

                if (httpContext.Request.Headers["If-Range"] != null)//对应响应头ETag:文件名+文件最后修改时间
                {
                    //----------上次被请求的日期之后被修改过--------------
                    if (httpContext.Request.Headers["If-Range"].Replace("\"", "") != eTag)
                    {//文件修改过
                        httpContext.Response.StatusCode = 412;//预处理失败
                        return false;
                    }
                }
                #endregion

                try
                {
                    #region -------添加重要响应头、解析请求头、相关验证
                    httpContext.Response.Clear();

                    if (httpContext.Request.Headers["Range"] != null)
                    {//------如果是续传请求,则获取续传的起始位置,即已经下载到客户端的字节数------
                        httpContext.Response.StatusCode = 206;//重要:续传必须,表示局部范围响应。初始下载时默认为200
                        string[] range = httpContext.Request.Headers["Range"].Split(new char[] { '=', '-' });//"bytes=1474560-"
                        startBytes = Convert.ToInt64(range[1]);//已经下载的字节数,即本次下载的开始位置 
                        if (startBytes < 0 || startBytes >= fileLength)
                        {//无效的起始位置
                            return false;
                        }
                        if (range.Length == 3)
                        {
                            stopBytes = Convert.ToInt64(range[2]);//结束下载的字节数,即本次下载的结束位置 
                            if (startBytes < 0 || startBytes >= fileLength)
                            {
                                return false;
                            }
                        }
                    }

                    httpContext.Response.Buffer = false;
                    httpContext.Response.AddHeader("Content-MD5", My_Des.MD5JiaMi_File(filePath));//用于验证文件
                    httpContext.Response.AddHeader("Accept-Ranges", "bytes");//重要:续传必须
                    httpContext.Response.AppendHeader("ETag", "\"" + eTag + "\"");//重要:续传必须
                    httpContext.Response.AppendHeader("Last-Modified", lastUpdateTiemStr);//把最后修改日期写入响应               
                    httpContext.Response.ContentType = "application/octet-stream";//MIME类型:匹配任意文件类型
                    httpContext.Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(fileName, Encoding.UTF8).Replace("+", "%20"));
                    httpContext.Response.AddHeader("Content-Length", (fileLength - startBytes).ToString());
                    httpContext.Response.AddHeader("Connection", "Keep-Alive");
                    httpContext.Response.ContentEncoding = Encoding.UTF8;
                    if (startBytes > 0)
                    {//------如果是续传请求,告诉客户端本次的开始字节数,总长度,以便客户端将续传数据追加到startBytes位置后----------
                        httpContext.Response.AddHeader("Content-Range", string.Format("bytes {0}-{1}/{2}", startBytes, fileLength - 1, fileLength));
                    }
                    #endregion

                    #region -------向客户端发送数据块-------------------
                    br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
                    int maxCount = (int)Math.Ceiling((fileLength - startBytes + 0.0) / packSize);//分块下载,剩余部分可分成的块数
                    for (int i = 0; i < maxCount && httpContext.Response.IsClientConnected; i++)
                    {//客户端中断连接,则暂停
                        httpContext.Response.BinaryWrite(br.ReadBytes(packSize));
                        httpContext.Response.Flush();
                        if (sleep > 1) Thread.Sleep(sleep);
                    }
                    #endregion
                }
                catch
                {
                    ret = false;
                }
                finally
                {
                    br.Close();
                    myFile.Close();
                }
            }
            catch
            {
                ret = false;
            }
            return ret;
        }
0
letjs_in
letjs_in
ajax不能实现下载,你需要单独设置一个form然后action定位到ashx这样才会下载文件。
0
笨蛋EGG
笨蛋EGG

我会错意了···不好意思·········还错占这么大的篇幅···对自己汗颜一下······

道歉!

letjs_in
letjs_in
\(^o^)/~
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