The AbstractFile class, as well as all the classes that derive from the AbstractFile class, can be derived from to create custom file classes.
Basic Steps
When creating a class that derives from the AbstractFile class or one of its derived classes, the following functions must be implemented:
| Method/Property |
Description |
| DoSize |
Gets the size of the file in bytes. |
| DoOpenRead |
Opens the file for reading. |
| DoOpenWrite |
Opens the file for writing. |
| DoName |
Gets or sets the short name of the item. |
| DoFullName |
Gets the full name of the item. |
| DoAttributes |
Gets or sets the attributes of the item. If your custom file does not support attributes, override the DoHasAttributes property and return false. This will prevent the DoAttributes method from being called needlessly. |
| DoCreationDateTime |
Gets or sets the creation date and time of the item. If your custom file does not support having a creation date and time, override the DoHasCreationDateTime property and return false. This will prevent the DoCreationDateTime method from being called needlessly. |
| DoLastWriteDateTime |
Gets or sets the modification date and time of the item. If your custom file does not support having a last write date and time, override the DoHasLastWriteDateTime property and return false. This will prevent the DoLastWriteDateTime method from being called needlessly. |
| DoLastAccessDateTime |
Gets or sets the last access date and time of the item. If your custom file does not support having a last access date and time, override the DoHasLastAccessDateTime property and return false. This will prevent the DoLastAccessDateTime method from being called needlessly. |
| DoParentFolder |
Gets a reference to the parent folder of this item. |
| DoRootFolder |
Gets a reference to the root folder of this item. |
| DoExists |
Gets a boolean value indicating if the item physically exists. |
| DoRefresh |
Re-reads the information from the physical item. |
| DoCreate |
Creates the physical item represented by the FileSystemItem object. |
| DoDelete |
Permanently deletes the physical item. |
| IsSameAs |
Gets a boolean value indicating if the source and target items are the same. |
| IsPathRooted |
Returns a boolean value indicating if the path passed is rooted in the environment of the FileSystemItem object we are dealing with. |
Each of the overridden abstract "Do" methods and properties are called by their corresponding public counterparts and are responsible for executing the actual operation. The public method simply validates the parameters. It is the "Do" implementation that must make sure that the required conditions are met. For example, in order to call delete on an item, it must first exist. This means that your implementation of DoDelete must throw an ItemDoesNotExistException if the item does not exist.
Template
The following example demonstrates the minimum implementation required for a class that derives from the AbstractFile class.
| VB.NET |
 Copy Code |
|
Imports Xceed.FileSystem
Imports System.IO
Namespace Xceed.FileSystem.Samples
Public Class CustomFile
Inherits AbstractFile
Protected Overrides ReadOnly Property DoSize() As Long
Get
Return 0
End Get
End Property
Protected Overrides Function DoOpenRead(ByVal session As FileSystemEventsSession, _
ByVal share As FileShare) As Stream
Return Nothing
End Function
Protected Overrides Function DoOpenWrite(ByVal session As FileSystemEventsSession, _
ByVal overwrite As Boolean, _
ByVal share As FileShare) As Stream
Return Nothing
End Function
Protected Overrides Property DoName() As String
Get
Return Nothing
End Get
Set(ByVal Value As String)
End Set
End Property
Protected Overrides ReadOnly Property DoFullName() As String
Get
Return Nothing
End Get
End Property
Protected Overrides Property DoAttributes() As FileAttributes
Get
Return New FileAttributes()
End Get
Set(ByVal Value As FileAttributes)
End Set
End Property
Protected Overrides Property DoCreationDateTime() As DateTime
Get
Return New System.DateTime()
End Get
Set(ByVal Value As DateTime)
End Set
End Property
Protected Overrides Property DoLastWriteDateTime() As DateTime
Get
Return New System.DateTime()
End Get
Set(ByVal Value As DateTime)
End Set
End Property
Protected Overrides Property DoLastAccessDateTime() As DateTime
Get
Return New System.DateTime()
End Get
Set(ByVal Value As DateTime)
End Set
End Property
Protected Overrides ReadOnly Property DoParentFolder() As AbstractFolder
Get
Return Nothing
End Get
End Property
Protected Overrides ReadOnly Property DoRootFolder() As AbstractFolder
Get
Return Nothing
End Get
End Property
Protected Overrides ReadOnly Property DoExists() As Boolean
Get
Return True
End Get
End Property
Protected Overrides Sub DoRefresh(ByVal session As FileSystemEventsSession)
End Sub
Protected Overrides Sub DoCreate(ByVal session As FileSystemEventsSession)
End Sub
Protected Overrides Sub DoDelete(ByVal session As FileSystemEventsSession)
End Sub
Protected Overrides Function IsSameAs(ByVal target As FileSystemItem) As Boolean
Return True
End Function
Protected Overrides Function IsPathRooted(ByVal path As String) As Boolean
Return True
End Function
End Class
End Namespace
|
| C# |
Copy Code |
|
using System;
using System.IO;
using Xceed.FileSystem;
namespace Xceed.FileSystem.Samples
{
public class CustomFile : AbstractFile
{
public CustomFile()
{
}
protected override long DoSize
{
get { return 0; }
}
protected override Stream DoOpenRead(FileSystemEventsSession session, FileShare share)
{
return null;
}
protected override Stream DoOpenWrite(FileSystemEventsSession session, bool overwrite, FileShare share)
{
return null;
}
protected override string DoName
{
get { return null; }
set { }
}
protected override string DoFullName
{
get { return null; }
}
protected override FileAttributes DoAttributes
{
get { return new FileAttributes(); }
set { }
}
protected override DateTime DoCreationDateTime
{
get { return new DateTime(); }
set { }
}
protected override DateTime DoLastWriteDateTime
{
get { return new DateTime(); }
set { }
}
protected override DateTime DoLastAccessDateTime
{
get { return new DateTime(); }
set { }
}
protected override AbstractFolder DoParentFolder
{
get { return null; }
}
protected override AbstractFolder DoRootFolder
{
get { return null; }
}
protected override bool DoExists
{
get { return true; }
}
protected override void DoRefresh(FileSystemEventsSession session)
{
}
protected override void DoCreate(FileSystemEventsSession session)
{
}
protected override void DoDelete(FileSystemEventsSession session)
{
}
protected override bool IsSameAs(FileSystemItem target)
{
return true;
}
protected override bool IsPathRooted(string path)
{
return true;
}
}
}
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