.NET开发

本类阅读TOP10

Public Class singleton

    'Name that will be used as key for Session object

    Private Const SESSION_SINGLETON As String = "SINGLETON"

    'Variables to store the data (used to be individual

    'session key/value pairs)

    Dim _lastName As String = ""

    Dim _firstName As String = ""

    Public Property LastName() As String

        Get

            Return _lastName

        End Get

        Set(ByVal Value As String)

            _lastName = Value

        End Set

    End Property

    Public Property FirstName() As String

        Get

            Return _firstName

        End Get

        Set(ByVal Value As String)

            _firstName = Value

        End Set

    End Property

    'Private constructor so cannot create an instance

    ' without using the correct method.  This is

    ' this is critical to properly implementing

    ' as a singleton object, objects of this

    ' class cannot be created from outside this

    ' class

    Private Sub New()

    End Sub

    'Create as a static method so this can be called using

    'just the class name (no object instance is required).

    'It simplifies other code because it will always return

    'the single instance of this class, either newly created

    'or from the session

    Public Shared Function GetCurrentSingleton() As singleton

        Dim oSingleton As singleton

        If System.Web.HttpContext.Current.Session(SESSION_SINGLETON) Is Nothing Then

            'No current session object exists, use private constructor to

            'create an instance, place it into the session

            oSingleton = New singleton

            System.Web.HttpContext.Current.Session(SESSION_SINGLETON) = oSingleton

        Else

            'Retrieve the already instance that was already created

            oSingleton = CType(System.Web.HttpContext.Current.Session(SESSION_SINGLETON), singleton)

        End If

        'Return the single instance of this class that was stored in the session

        Return oSingleton

    End Function

End Class

public class singleton

{

//Name that will be used as key for Session object

private const string SESSION_SINGLETON = "SINGLETON";

//Variables to store the data (used to be individual

// session key/value pairs)

string lastName = "";

string firstName = "";

public string LastName

{

get

{

return lastName;

}

set

{

lastName = value;

}

}

public string FirstName

{

get

{

return firstName;

}

set

{

firstName = value;

}

}

//Private constructor so cannot create an instance

// without using the correct method.  This is

// this is critical to properly implementing

// as a singleton object, objects of this

// class cannot be created from outside this

// class

private singleton()

{

}

//Create as a static method so this can be called using

// just the class name (no object instance is required).

// It simplifies other code because it will always return

// the single instance of this class, either newly created

// or from the session

public static singleton GetCurrentSingleton()

{

singleton oSingleton;

if (null == System.Web.HttpContext.Current.Session[SESSION_SINGLETON])

{

//No current session object exists, use private constructor to

// create an instance, place it into the session

oSingleton = new singleton();

System.Web.HttpContext.Current.Session[SESSION_SINGLETON] = oSingleton;

}

else

{

//Retrieve the already instance that was already created

oSingleton = (singleton)System.Web.HttpContext.Current.Session[SESSION_SINGLETON];

}

//Return the single instance of this class that was stored in the session

return oSingleton;

}

}

singleton oSingleton = singleton.GetCurrentSingleton();

oSingleton.FirstName = "Robert";

oSingleton.LastName = "Boedigheimer";

public static void Dispose()

{

//Cleanup this object so that GC can reclaim space

System.Web.HttpContext.Current.Session.Remove(SESSION_SINGLETON);

}