Professional ASP.NET 3.5 in C# and Visual Basic Part 120 potx

Evjen c25.tex V2 - 01/28/2008 3:42pm Page 1150
Chapter 25: File I/O and Streams
file. (If you want to display only the filenames, you could use the
Directory
class’s
GetFiles()
method,
which returns a simple string array of filenames.)
Figure 25-4
Listing 25-6 shows how to use the TreeView control’s
SelectedNodeChanged
event to bind your
GridView
with the file information.
Listing 25-6: Binding a GridView to directory files
VB
<
script runat="server"
>
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
If (Not Page.IsPostBack) Then
For Each drive As System.IO.DriveInfo In System.IO.DriveInfo.GetDrives()
Dim node As TreeNode = New TreeNode()
node.Value = drive.Name
If (drive.IsReady) Then
node.Text = drive.Name & _
" - (free space: " & drive.AvailableFreeSpace & ")"
LoadDirectories(node, drive.Name)
Else
node.Text = drive.Name & " - (not ready)"
End If

Me.TreeView1.Nodes.Add(node)
Next
End If
Me.TreeView1.CollapseAll()
Continued
1150
Evjen c25.tex V2 - 01/28/2008 3:42pm Page 1151
Chapter 25: File I/O and Streams
End Sub
Private Sub LoadDirectories(ByVal parent As TreeNode, ByVal path As String)
Dim directory As System.IO.DirectoryInfo = _
New System.IO.DirectoryInfo(path)
Try
For Each d As System.IO.DirectoryInfo In directory.GetDirectories()
Dim node As TreeNode = New TreeNode(d.Name, d.FullName)
parent.ChildNodes.Add(node)
’Recurse the current directory
LoadDirectories(node, d.FullName)
Next
Catch ex As System.UnauthorizedAccessException
parent.Text += " (Access Denied)"
Catch ex As Exception
parent.Text += " (Unknown Error: " + ex.Message + ")"
End Try
End Sub
Protected Sub TreeView1_SelectedNodeChanged _
(ByVal sender As Object, ByVal e As System.EventArgs)
Dim directory As System.IO.DirectoryInfo = _
New System.IO.DirectoryInfo(Me.TreeView1.SelectedNode.Value)
Me.GridView1.DataSource = directory.GetFiles()

Me.GridView1.DataBind()
End Sub
<
/script
>
<
html xmlns=" />>
<
head runat="server"
>
<
title
>
Binding a Gridview
<
/title
>
<
/head
>
<
body
>
<
form id="form1" runat="server"
>
<
div
>
<

table
>
<
tr
>
<
td style="width: 100px" valign="top"
>
<
asp:TreeView ID="TreeView1" runat="server"
OnSelectedNodeChanged="TreeView1_SelectedNodeChanged"
>
<
/asp:TreeView
>
<
/td
>
<
td valign=top
>
<
asp:GridView ID="GridView1" runat="server"
AutoGenerateColumns=False GridLines=None CellPadding=3
>
Continued
1151
Evjen c25.tex V2 - 01/28/2008 3:42pm Page 1152
Chapter 25: File I/O and Streams
<

Columns
>
<
asp:BoundField DataField="Name" HeaderText="Name"
HeaderStyle-HorizontalAlign=Left
HeaderStyle-Font-Bold=true /
>
<
asp:BoundField DataField="Length" HeaderText="Size"
ItemStyle-HorizontalAlign=Right
HeaderStyle-HorizontalAlign=Right
HeaderStyle-Font-Bold=true /
>
<
asp:BoundField DataField="LastWriteTime"
HeaderText="Date Modified"
HeaderStyle-HorizontalAlign=Left
HeaderStyle-Font-Bold=true /
>
<
/Columns
>
<
/asp:GridView
>
<
/td
>
<
/tr

>
<
/table
>
<
/div
>
<
/form
>
<
/body
>
<
/html
>
C#
<
script runat="server"
>
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
foreach (System.IO.DriveInfo drive in System.IO.DriveInfo.GetDrives())
{
TreeNode node = new TreeNode();
node.Value = drive.Name;
// Make sure the drive is ready before we access it
if (drive.IsReady)

{
node.Text = drive.Name +
" - (free space: " + drive.AvailableFreeSpace + ")";
LoadDirectories(node, drive.Name);
}
else
node.Text = drive.Name + " - (not ready)";
this.TreeView1.Nodes.Add(node);
}
}
this.TreeView1.CollapseAll();
}
Continued
1152
Evjen c25.tex V2 - 01/28/2008 3:42pm Page 1153
Chapter 25: File I/O and Streams
private void LoadDirectories(TreeNode parent, string path)
{
System.IO.DirectoryInfo directory = new System.IO.DirectoryInfo(path);
try
{
foreach (System.IO.DirectoryInfo d in directory.GetDirectories())
{
TreeNode node = new TreeNode(d.Name, d.FullName);
parent.ChildNodes.Add(node);
//Recurse the current directory
LoadDirectories(node, d.FullName);
}
}
catch (System.UnauthorizedAccessException e)

{
parent.Text += " (Access Denied)";
}
catch (Exception e)
{
parent.Text += " (Unknown Error: " + e.Message + ")";
}
}
protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
{
System.IO.DirectoryInfo directory =
new System.IO.DirectoryInfo(this.TreeView1.SelectedNode.Value);
this.GridView1.DataSource = directory.GetFiles();
this.GridView1.DataBind();
}
<
/script
>
Figure 25-5 shows what your Web page looks like after you have selected a directory and your grid has
been bound to the
FileInfo
array.
Keep in mind that, as in the Load Directory example, you can also enumerate though the
FileInfo
array
to display the information. Listing 25-7 shows you how to enumerate through the
FileInfo
array and
display the properties to the page.
Listing 25-7: Manually enumerating directory files

VB
Dim dir as New System.IO.DirectoryInfo("C:
\
")
For Each file as System.IO.FileInfo In dir.GetFiles("*.*")
Response.Write(file.Name & "
<
BR
>
")
Response.Write(file.LastWriteTime.ToString() & "
<
BR
>
")
Response.Write(file.Attributes.ToString() & "
<
BR
>
")
Next
Continued
1153
Evjen c25.tex V2 - 01/28/2008 3:42pm Page 1154
Chapter 25: File I/O and Streams
C#
System.IO.DirectoryInfo dir = new System.IO.DirectoryInfo(@"C:
\
");
foreach (System.IO.FileInfo file in dir.GetFiles("*.*"))

{
Response.Write(file.Name + "
<
BR
>
");
Response.Write(file.LastWriteTime.ToString() + "
<
BR
>
");
Response.Write(file.Attributes.ToString() + "
<
BR
>
");
}
Figure 25-5
Listing 25-7 also shows that you can provide a file filter to the
GetFiles()
method.Thisallowsyouto
limit the results from the method to specific file extensions or to files matching a specific filename part.
Working with Paths
Although working with files and directories has been pretty easy, even going all the way back to good
old ASP, one of the most problematic areas has always been working with paths. Many lines of code
have been written by developers to deal with concatenating partial paths together, making sure files
have extensions, evaluating those extensions, stripping filenames off of paths, and even more.
Thankfully, the .NET Framework provides you with a class just for dealing with paths. The
System.IO.Path
class exposes a handful of static methods that make dealing with paths a snap. The

following table lists the static methods exposed by the
Path
class.
1154
Evjen c25.tex V2 - 01/28/2008 3:42pm Page 1155
Chapter 25: File I/O and Streams
Method Description
ChangeExtension
Changes the extension of the provided path string to the provided
new extension.
Combine
Returns a single combined path from two partial path strings.
GetDirectoryName
Returns the directory or directories of the provided path.
GetExtension
Returns the extension of the provided path.
GetFileName
Returns the filename of the provided path.
GetFileNameWithoutExtension
Returns the filename without its extension of the provided path.
GetFullPath
Given a non-rooted path, returns a rooted pathname based on the
current working directory. For example, if the path passed in is
"temp"
and the current working directory is
c:
\
MyWebsite
,the
method returns

C:
\
MyWebsite
\
temp
.
GetInvalidFileNameChars
Returns an array of characters that are not allowed in filenames
for the current system.
GetInvalidPathChars
Returns an array of characters that are not allowed in pathnames
for the current system.
GetPathRoot
Returns the root path.
GetTempFileName
Returns a temporary filename, located in the temporary directory
returned
by
GetTempPath
.
GetTempPath
Returns the temporary directory name.
HasExtension
Returns a Boolean value indicating whether a path has an
extension.
IsPathRooted
Returns a Boolean indicating if a path is rooted.
As an example of using the
Path
class, the application shown in Figure 25-6 lets you enter a path and then

displays the component parts of the path such as the root path (logical drive), the directory, filename, and
extension.
The
GetInvalidPathChars
and
GetInvalidFileNameChars
methods return an array of characters
that are not allowed in path and filenames, respectively. Although the specific invalid characters are
dependent on the platform the application is running on, the arrays returned by these methods will most
likely contain elements such as non-printable characters, special Unicode characters, or characters from
non-Latin–based character sets. The characters that your browser is capable of rendering will depend on
your specific platform setup. Characters that your browser is incapable of rendering properly will display
as the generic square box shown in Figure 25-6.
The code in Listing 25-8 shows how the various methods and constant properties of the
Path
class have
been used to create the application shown in Figure 25-6.
1155
Evjen c25.tex V2 - 01/28/2008 3:42pm Page 1156
Chapter 25: File I/O and Streams
Figure 25-6
Listing 25-8: Using the Path class
VB
<
%@ Import Namespace="System.IO" %
>
<
script runat="server"
>
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

If Page.IsPostBack Then
Me.lblRootPath.Text = Path.GetPathRoot(Me.txtPathName.Text)
Me.lblDirectoryName.Text = Path.GetDirectoryName(Me.txtPathName.Text)
Me.lblFileName.Text = Path.GetFileName(Me.txtPathName.Text)
Me.lblFileNameWithoutExtension.Text = _
Path.GetFileNameWithoutExtension(Me.txtPathName.Text)
Me.lblExtension.Text = Path.GetExtension(Me.txtPathName.Text)
Me.lblTemporaryPath.Text = Path.GetTempPath()
Me.lblDirectorySeparatorChar.Text = _
Path.DirectorySeparatorChar.ToString()
Me.lblAltDirectorySeparatorChar.Text = _
Path.AltDirectorySeparatorChar.ToString()
Me.lblVolumeSeparatorChar.Text = Path.VolumeSeparatorChar.ToString()
Me.lblPathSeparator.Text = Path.PathSeparator.ToString()
Me.lblInvalidChars.Text = _
HttpUtility.HtmlEncode(New String(Path.GetInvalidPathChars()))
Continued
1156
Evjen c25.tex V2 - 01/28/2008 3:42pm Page 1157
Chapter 25: File I/O and Streams
Me.lblInvalidFileNameChars.Text = _
HttpUtility.HtmlEncode(New String(Path.GetInvalidFileNameChars()))
End If
End Sub
<
/script
>
<
html xmlns=" />>
<

head runat="server"
>
<
title
>
Using the Path Class
<
/title
>
<
/head
>
<
body
>
<
form id="form1" runat="server"
>
<
div
>
Working with the Path Class
<
br /
>
<
br /
>
Enter a path name:
<

asp:TextBox ID="txtPathName" runat="server"
><
/asp:TextBox
><
br /
>
<
asp:Button ID="Button1" runat="server" Text="Button" /
><
br /
>
<
br /
>
Root Path =
<
asp:Label ID="lblRootPath" runat="server" Text="Label" /
>
<
br /
>
Directory =
<
asp:Label ID="lblDirectoryName" runat="server" Text="Label" /
>
<
br /
>
Filename =
<

asp:Label ID="lblFileName" runat="server" Text="Label" /
>
<
br /
>
Filename (without extension) =
<
asp:Label ID="lblFileNameWithoutExtension" runat="server" Text="Label" /
>
<
br /
>
Extension =
<
asp:Label ID="lblExtension" runat="server" Text="Label" /
>
<
br /
>
<
br /
>
Temporary Directory =
<
asp:Label ID="lblTemporaryPath" runat="server" Text="Label" /
>
<
br /
>
Directory Separator Character =

<
asp:Label ID="lblDirectorySeparatorChar" runat="server" Text="Label" /
>
<
br /
>
Alt Directory Separator Character =
<
asp:Label ID="lblAltDirectorySeparatorChar" runat="server" Text="Label" /
>
<
br /
>
Volume Separator Character =
<
asp:Label ID="lblVolumeSeparatorChar" runat="server" Text="Label" /
>
<
br /
>
Path Separator Character =
<
asp:Label ID="lblPathSeparator" runat="server" Text="Label" /
>
<
br /
>
Invalid Path Characters =
<
asp:Label ID="lblInvalidChars" runat="server" Text="Label" /

>
<
br /
>
Invalid FileName Characters =
Continued
1157
Evjen c25.tex V2 - 01/28/2008 3:42pm Page 1158
Chapter 25: File I/O and Streams
<
asp:Label ID="lblInvalidFileNameChars" runat="server" Text="Label" /
>
<
/div
>
<
/form
>
<
/body
>
<
/html
>
C#
<
%@ Import Namespace="System.IO" %
>
<
script runat="server"

>
protected void Page_Load(object sender, EventArgs e)
{
if (Page.IsPostBack)
{
this.lblRootPath.Text =
Path.GetPathRoot(this.txtPathName.Text);
this.lblDirectoryName.Text =
Path.GetDirectoryName(this.txtPathName.Text);
this.lblFileName.Text =
Path.GetFileName(this.txtPathName.Text);
this.lblFileNameWithoutExtension.Text =
Path.GetFileNameWithoutExtension(this.txtPathName.Text);
this.lblExtension.Text =
Path.GetExtension(this.txtPathName.Text);
this.lblTemporaryPath.Text = Path.GetTempPath();
this.lblDirectorySeparatorChar.Text =
Path.DirectorySeparatorChar.ToString();
this.lblAltDirectorySeparatorChar.Text =
Path.AltDirectorySeparatorChar.ToString();
this.lblVolumeSeparatorChar.Text = Path.VolumeSeparatorChar.ToString();
this.lblPathSeparator.Text = Path.PathSeparator.ToString();
this.lblInvalidChars.Text =
HttpUtility.HtmlEncode( new String(Path.GetInvalidPathChars() ) );
this.lblInvalidFileNameChars.Text =
HttpUtility.HtmlEncode( new String(Path.GetInvalidFileNameChars()));
}
}
<
/script

>
File and Directory Properties, Attributes,
and Access Control Lists
Finally, this section explains how you can access and modify file and directory properties, attributes, and
Access Control Lists.
Samples in this section use a simple text file called
TextFile.txt
to demonstrate the concepts. You can
either create this file or substitute your own file i n the sample code. The samples assume the file has been
added to the Web site and use the
Server.MapPath
method to determine the full filepath.
1158
Evjen c25.tex V2 - 01/28/2008 3:42pm Page 1159
Chapter 25: File I/O and Streams
Properties and Attributes
Files and directories share certain properties that you can use to determine the age o f a file or direc-
tory, when it was last modified, and what attributes have been applied. These properties can be viewed
by opening the file’s Properties dialog. You can open this dialog from Windows Explorer by either
right-clicking on the file and selecting Properties from the context menu, or selecting Properties from
the File menu. Figure 25-7 shows the file’s Properties window for the text document.
Figure 25-7
Both the
DirectoryInfo
and the
FileInfo
classes let you access these properties and modify them.
Listing 25-9 shows you an example of displaying the file properties.
Listing 25-9: Displaying and modifying the file properties
VB

Dim file As New System.IO.FileInfo(Server.MapPath("TextFile.txt"))
Response.Write("Location: " & file.FullName & "
<
BR
>
")
Response.Write("Size: " & file.Length & "
<
BR
>
")
Response.Write("Created: " & file.CreationTime & "
<
BR
>
")
Response.Write("Modified: " & file.LastWriteTime & "
<
BR
>
")
Response.Write("Accessed: " & file.LastAccessTime & "
<
BR
>
")
Response.Write("Attributes: " & file.Attributes)
Continued
1159