asp.net 中一次上传多个文件

看到一篇老外的文章，说在asp.net 中，如何先让用户把要上传的文件都选好了，然后一次上传，

今小结如下

首先在页面加一个上传文件控件，一个“attach"按钮，一个listbox，用来存放等待上传的文件名，

一个"UPLOAD"按钮，一个”删除按钮

<form 按钮中代码如下：

private void btnAttach_Click(object sender, System.EventArgs e)

{

// Save the attached file to fileName variable

string fileName = FileUpload.PostedFile.FileName;

// If the counter is null then create one with default value equal to 0

if(ViewState["i"] == null)

{

ViewState["i"]= 0;

}

// Check if a file is selected

if(fileName != null || fileName != string.Empty)

{

// Add it to the collection

ListBox1.Items.Add(FileUpload.PostedFile.FileName);

// Save an index for each selected file

int i = Convert.ToInt32(ViewState["i"]);

// Save the fileupload control into a different session

Session["myupload" + i] = FileUpload;

// Increment the counter

i++;

// Set the ViewSate to the latest counter value.

ViewState["i"] = i;

}

}

很明显，其实是用viewstate来存放用户上传的实际文件名，这需要用户在选择文件后用

"attach"按钮来将文件添加到那个listbox框中去

之后是“upload"的代码，

private void btnUpload_Click(object sender, System.EventArgs e)

{

int sessionCount = Session.Count;

///int sessionCount = Convert.ToInt32(ViewState["i"]);

for( int i =sessionCount-1;i>=0;i--)

{

if(sessionCount <= 3)

{

HtmlInputFile hif = (HtmlInputFile)Session["myupload" + i];

if(hif.PostedFile.ContentLength <= 500000)

{

string storePath = Server.MapPath("~") + "/MultipleUpload";

if(!Directory.Exists(storePath))

Directory.CreateDirectory(storePath);

hif.PostedFile.SaveAs(storePath + "/" + Path.GetFileName(hif.PostedFile.FileName));

Label1.Text = "Your Files are uploaded successfully";

ListBox1.Items.Clear();

}

else

Label1.Text = "An error occured";

}

else

Label1.Text = "You have exceeded the maximum number of files to be uploaded (3)";

}

Session.RemoveAll();

}

实际上是将所有的要上传的文件从session里取回来，然后每一个逐一上传

最后是把要上传的文件从listbox里删除的代码，在session里remove掉

private void btnDelete_Click(object sender, System.EventArgs e)

{

if(ListBox1.SelectedIndex > -1)

{

int uploadedFileIndex = ListBox1.SelectedIndex;

Session.Remove("myupload" + uploadedFileIndex);

ListBox1.Items.Remove(ListBox1.SelectedValue);

}

}

总结一下，用在上传文件不多的情况下比较好，因为要用session