復制代碼 代碼如下:

Boolean fileOk = false;
string path = Server.MapPath("~/images/");
//判斷是否已經選取文件
if (FileUpload1.HasFile)
{
//取得文件的擴展名,并轉換成小寫
string fileExtension = System.IO.Path.GetExtension(FileUpload1.FileName).ToLower();
//限定只能上傳jpg和gif圖片
string[] allowExtension = { ".jpg", ".gif" };
//對上傳的文件的類型進行一個個匹對
int j = 0;
for (int i = 0; i < allowExtension.Length; i++)
{
if (fileExtension == allowExtension[i])
{
fileOk = true;
return;
}
else
{
j++;
}
}
if (j > 0)
{
Response.Write("<script>alert('文件格式不正確');</script>");
return;
}
}
else
{
Response.Write("<script>alert('你還沒有選擇文件');</script>");
return;
}
//如果擴展名符合條件，則上傳
if (fileOk)
{
FileUpload1.PostedFile.SaveAs(path + FileUpload1.FileName);
Response.Write("<script>alert('上傳成功');</script>");
}

復制代碼 代碼如下:

Boolean fileOk = false;
string path = Server.MapPath("~/images/");
//判斷是否已經選取文件
if (FileUpload1.HasFile)
{
//取得文件MIME內容類型
string type = this.FileUpload1.PostedFile.ContentType.ToLower();
if (type.Contains("image")) //圖片的MIME類型為"image/xxx"，這里只判斷是否圖片。
{
fileOk = true;
}
else
{
Response.Write("<script>alert('格式不正確')</script>");
}
}
else
{
Response.Write("<script>alert('你還沒有選擇文件');</script>");
}
//如果擴展名符合條件，則上傳
if (fileOk)
{
FileUpload1.PostedFile.SaveAs(path + FileUpload1.FileName);
Response.Write("<script>alert('上傳成功');</script>");
}

復制代碼 代碼如下:

try
{
//判斷是否已經選取文件
if (FileUpload1.HasFile)
{
if (IsAllowedExtension(FileUpload1))
{
string path = Server.MapPath("~/images/");
FileUpload1.PostedFile.SaveAs(path + FileUpload1.FileName);
Response.Write("<script>alert('上傳成功');</script>");
}
else
{
Response.Write("<script>alert('您只能上傳jpg或者gif圖片');</script>");
}
}
else
{
Response.Write("<script>alert('你還沒有選擇文件');</script>");
}
}
catch (Exception error)
{
Response.Write(error.ToString());
}
#endregion
}
//真正判斷文件類型的關鍵函數
public static bool IsAllowedExtension(FileUpload hifile)
{
System.IO.FileStream fs = new System.IO.FileStream(hifile.PostedFile.FileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
System.IO.BinaryReader r = new System.IO.BinaryReader(fs);
string fileclass = "";
//這里的位長要具體判斷.
byte buffer;
try
{
buffer = r.ReadByte();
fileclass = buffer.ToString();
buffer = r.ReadByte();
fileclass += buffer.ToString();
}
catch
{
}
r.Close();
fs.Close();
if (fileclass == "255216" || fileclass == "7173")//說明255216是jpg;7173是gif;6677是BMP,13780是PNG;7790是exe,8297是rar
{
return true;
}
else
{
return false;
}
}