C# ASP 上传/下载文件

1.  上传文件前台页面

1            <div style="padding-left:20px;">
2                <asp:FileUpload ID="FileUpload1" runat="server" style="width:400px;"/>
3                <asp:Button ID="Button1" runat="server" OnClick="Upload_Click" Text="上传" style="width:65px;height:22px"></asp:Button >
4             </div>

　　上传文件后台代码

 1     private string _directory = @"../Questionnaire35";
 2
 3     protected void Upload_Click(object sender, EventArgs e)
 4     {
 5         try
 6         {
 7             if (Request.Files.Count > 0)
 8             {
 9                 if (string.IsNullOrEmpty(Request.Files[0].FileName))
10                 {
11                     return;
12                 }
13                 //判断文件大小
14                 int length = Request.Files[0].ContentLength;
15                 if (length > 1048576)
16                 {
17                     Page.ClientScript.RegisterStartupScript(this.GetType(), "alert", "<script>alert(‘文件大于1M，不能上传‘);</script>");
18                     return;
19                 }
20
21                 string type = Request.Files[0].ContentType;
22                 string fileExt = Path.GetExtension(Request.Files[0].FileName).ToLower();
23                 //只能上传图片，过滤不可上传的文件类型
24                 string fileFilt = ".xlsx|.xls|.docx|.doc|......";
25                 if (fileFilt.IndexOf(fileExt) <= -1)
26                 {
27                     Page.ClientScript.RegisterStartupScript(this.GetType(), "alert", "<script>alert(‘只能上传文档‘);</script>");
28                     return;
29                 }
30                 else
31                 {
32                     UserInfo user = (UserInfo)Session["UserInfo"];
33                     //string fileName = Server.MapPath(_directory) + "\\" + DateTime.Now.ToString("yyyyMMddHHmmssfff") + fileExt;
34                     string fileName = Server.MapPath(_directory) + "\\" + user.Pkid + fileExt;
35                     Request.Files[0].SaveAs(fileName);
36                     Page.ClientScript.RegisterStartupScript(this.GetType(), "alert", "<script>alert(‘上传成功‘);</script>");
37                     Answer answer = (Answer)Session["Answer"];
38                     answer.Answer35 = "done";
39                 }
40             }
41         }
42         catch
43         {
44             throw new Exception();
45         }
46     }

　　需要引入 using System.IO;

2. 下载文件前台页面

1 <asp:LinkButton runat="server" ID="DownLoadQuestionnaire" Text="下载文件" OnClick="DownLoadQuestionnaire_Click" />

下载文件后台代码

 1     protected void DownLoadQuestionnaire_Click(object sender, EventArgs e)
 2     {
 3         Response.ContentType = "application/x-zip-compressed";
 4
 5         string docName = "中高职衔接院校调研问卷.docx"; //文件路径
 6         docName = HttpUtility.UrlEncode(docName, System.Text.Encoding.UTF8);
 7         Response.AddHeader("Content-Disposition", "attachment;filename=" + docName);
 8         string filename = Server.MapPath("DownLoad/中高职衔接院校调研问卷.docx");
 9         //指定编码 防止中文文件名乱码
10         Response.HeaderEncoding = System.Text.Encoding.GetEncoding("GB2312");
11         Response.TransmitFile(filename);
12
13     }

　　值得注意的就是文件名设置一下编码，不然出现下载时文件名乱码：

　　HttpUtility.UrlEncode(docName, System.Text.Encoding.UTF8);

　　据说还有很多种下载方式，没一个一个的试验：

 1     protected void DownLoadQuestionnaire_Click(object sender, EventArgs e)
 2     {
 3         string fileName = "asd.txt";//客户端保存的文件名
 4         string filePath = Server.MapPath("DownLoad/aaa.txt");//路径
 5
 6         FileInfo fileInfo = new FileInfo(filePath);
 7         Response.Clear();
 8         Response.ClearContent();
 9         Response.ClearHeaders();
10         Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);
11         Response.AddHeader("Content-Length", fileInfo.Length.ToString());
12         Response.AddHeader("Content-Transfer-Encoding", "binary");
13         Response.ContentType = "application/octet-stream";
14         Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");
15         Response.WriteFile(fileInfo.FullName);
16         Response.Flush();
17         Response.End();
18
19     }
20
21     protected void DownLoadQuestionnaire_Click(object sender, EventArgs e)
22     {
23         string fileName = "aaa.txt";//客户端保存的文件名
24         string filePath = Server.MapPath("DownLoad/aaa.txt");//路径
25         System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);
26         if (fileInfo.Exists == true)
27         {
28             const long ChunkSize = 102400;//100K 每次读取文件，只读取100K，这样可以缓解服务器的压力
29             byte[] buffer = new byte[ChunkSize];
30
31             Response.Clear();
32             System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);
33             long dataLengthToRead = iStream.Length;//获取下载的文件总大小
34             Response.ContentType = "application/octet-stream";
35             Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));
36             while (dataLengthToRead > 0 && Response.IsClientConnected)
37             {
38                 int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小
39                 Response.OutputStream.Write(buffer, 0, lengthRead);
40                 Response.Flush();
41                 dataLengthToRead = dataLengthToRead - lengthRead;
42             }
43             Response.Close();
44         }
45     }
46
47     protected void DownLoadQuestionnaire_Click(object sender, EventArgs e)
48     {
49         string fileName = "aaa.txt";//客户端保存的文件名
50         string filePath = Server.MapPath("DownLoad/aaa.txt");//路径
51
52         //以字符流的形式下载文件
53         FileStream fs = new FileStream(filePath, FileMode.Open);
54         byte[] bytes = new byte[(int)fs.Length];
55         fs.Read(bytes, 0, bytes.Length);
56         fs.Close();
57         Response.ContentType = "application/octet-stream";
58         //通知浏览器下载文件而不是打开
59         Response.AddHeader("Content-Disposition", "attachment;  filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
60         Response.BinaryWrite(bytes);
61         Response.Flush();
62         Response.End();
63     }