ApplicationContext Classe
Importante
Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.
Specifica le informazioni contestuali relative a un thread dell'applicazione.
public ref class ApplicationContext
public ref class ApplicationContext : IDisposable
public class ApplicationContext
public class ApplicationContext : IDisposable
type ApplicationContext = class
type ApplicationContext = class
interface IDisposable
Public Class ApplicationContext
Public Class ApplicationContext
Implements IDisposable
- Ereditarietà
-
ApplicationContext
- Implementazioni
Nell'esempio di codice seguente vengono visualizzati due moduli e viene chiusa l'applicazione quando entrambe le forme vengono chiuse. All'avvio e all'uscita dell'applicazione, viene ricordata la posizione di ogni modulo. In questo esempio viene illustrato come usare un ApplicationContextoggetto , insieme al Application.Run(context)
metodo, per visualizzare più moduli all'avvio dell'applicazione.
La classe MyApplicationContext
eredita da ApplicationContext e mantiene traccia quando ogni modulo viene chiuso e chiude il thread corrente quando entrambi sono. La classe archivia le posizioni di ogni modulo per l'utente. I dati di posizione del modulo vengono archiviati in un file denominato Appdata.txt
creato nella posizione determinata da UserAppDataPath.
Il Main
metodo chiama Application.Run(context)
per avviare l'applicazione, in base a ApplicationContext.
#using <System.dll>
#using <System.Drawing.dll>
#using <System.Windows.Forms.dll>
using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
using namespace System::ComponentModel;
using namespace System::Text;
using namespace System::IO;
// A simple form that represents a window in our application
public ref class AppForm2: public System::Windows::Forms::Form
{
public:
AppForm2()
{
this->Size = System::Drawing::Size( 300, 300 );
this->Text = "AppForm2";
}
};
// A simple form that represents a window in our application
public ref class AppForm1: public System::Windows::Forms::Form
{
public:
AppForm1()
{
this->Size = System::Drawing::Size( 300, 300 );
this->Text = "AppForm1";
}
};
// The class that handles the creation of the application windows
ref class MyApplicationContext: public ApplicationContext
{
private:
int _formCount;
AppForm1^ _form1;
AppForm2^ _form2;
System::Drawing::Rectangle _form1Position;
System::Drawing::Rectangle _form2Position;
FileStream^ _userData;
public:
MyApplicationContext()
{
_formCount = 0;
// Handle the ApplicationExit event to know when the application is exiting.
Application::ApplicationExit += gcnew EventHandler( this, &MyApplicationContext::OnApplicationExit );
try
{
// Create a file that the application will store user specific data in.
_userData = gcnew FileStream( String::Concat( Application::UserAppDataPath, "\\appdata.txt" ),FileMode::OpenOrCreate );
}
catch ( IOException^ e )
{
// Inform the user that an error occurred.
MessageBox::Show( "An error occurred while attempting to show the application. The error is: {0}", dynamic_cast<String^>(e) );
// Exit the current thread instead of showing the windows.
ExitThread();
}
// Create both application forms and handle the Closed event
// to know when both forms are closed.
_form1 = gcnew AppForm1;
_form1->Closed += gcnew EventHandler( this, &MyApplicationContext::OnFormClosed );
_form1->Closing += gcnew CancelEventHandler( this, &MyApplicationContext::OnFormClosing );
_formCount++;
_form2 = gcnew AppForm2;
_form2->Closed += gcnew EventHandler( this, &MyApplicationContext::OnFormClosed );
_form2->Closing += gcnew CancelEventHandler( this, &MyApplicationContext::OnFormClosing );
_formCount++;
// Get the form positions based upon the user specific data.
if ( ReadFormDataFromFile() )
{
// If the data was read from the file, set the form
// positions manually.
_form1->StartPosition = FormStartPosition::Manual;
_form2->StartPosition = FormStartPosition::Manual;
_form1->Bounds = _form1Position;
_form2->Bounds = _form2Position;
}
// Show both forms.
_form1->Show();
_form2->Show();
}
void OnApplicationExit( Object^ /*sender*/, EventArgs^ /*e*/ )
{
// When the application is exiting, write the application data to the
// user file and close it.
WriteFormDataToFile();
try
{
// Ignore any errors that might occur while closing the file handle.
_userData->Close();
}
catch ( Exception^ )
{
}
}
private:
void OnFormClosing( Object^ sender, CancelEventArgs^ /*e*/ )
{
// When a form is closing, remember the form position so it
// can be saved in the user data file.
if ( dynamic_cast<AppForm1^>(sender) != nullptr )
_form1Position = (dynamic_cast<Form^>(sender))->Bounds;
else
if ( dynamic_cast<AppForm1^>(sender) != nullptr )
_form2Position = (dynamic_cast<Form^>(sender))->Bounds;
}
void OnFormClosed( Object^ /*sender*/, EventArgs^ /*e*/ )
{
// When a form is closed, decrement the count of open forms.
// When the count gets to 0, exit the app by calling
// ExitThread().
_formCount--;
if ( _formCount == 0 )
{
ExitThread();
}
}
bool WriteFormDataToFile()
{
// Write the form positions to the file.
UTF8Encoding^ encoding = gcnew UTF8Encoding;
RectangleConverter^ rectConv = gcnew RectangleConverter;
String^ form1pos = rectConv->ConvertToString( _form1Position );
String^ form2pos = rectConv->ConvertToString( _form2Position );
array<Byte>^dataToWrite = encoding->GetBytes( String::Concat( "~", form1pos, "~", form2pos ) );
try
{
// Set the write position to the start of the file and write
_userData->Seek( 0, SeekOrigin::Begin );
_userData->Write( dataToWrite, 0, dataToWrite->Length );
_userData->Flush();
_userData->SetLength( dataToWrite->Length );
return true;
}
catch ( Exception^ )
{
// An error occurred while attempting to write, return false.
return false;
}
}
bool ReadFormDataFromFile()
{
// Read the form positions from the file.
UTF8Encoding^ encoding = gcnew UTF8Encoding;
String^ data;
if ( _userData->Length != 0 )
{
array<Byte>^dataToRead = gcnew array<Byte>(_userData->Length);
try
{
// Set the read position to the start of the file and read.
_userData->Seek( 0, SeekOrigin::Begin );
_userData->Read( dataToRead, 0, dataToRead->Length );
}
catch ( IOException^ e )
{
String^ errorInfo = dynamic_cast<String^>(e);
// An error occurred while attempt to read, return false.
return false;
}
// Parse out the data to get the window rectangles
data = encoding->GetString( dataToRead );
try
{
// Convert the String* data to rectangles
RectangleConverter^ rectConv = gcnew RectangleConverter;
String^ form1pos = data->Substring( 1, data->IndexOf( "~", 1 ) - 1 );
_form1Position = *safe_cast<Rectangle^>(rectConv->ConvertFromString( form1pos ));
String^ form2pos = data->Substring( data->IndexOf( "~", 1 ) + 1 );
_form2Position = *safe_cast<Rectangle^>(rectConv->ConvertFromString( form2pos ));
return true;
}
catch ( Exception^ )
{
// Error occurred while attempting to convert the rectangle data.
// Return false to use default values.
return false;
}
}
else
{
// No data in the file, return false to use default values.
return false;
}
}
};
[STAThread]
int main()
{
// Create the MyApplicationContext, that derives from ApplicationContext,
// that manages when the application should exit.
MyApplicationContext^ context = gcnew MyApplicationContext;
// Run the application with the specific context. It will exit when
// all forms are closed.
Application::Run( context );
}
using System;
using System.Drawing;
using System.Windows.Forms;
using System.ComponentModel;
using System.Text;
using System.IO;
namespace MyApplication
{
// A simple form that represents a window in our application
public class AppForm2 : System.Windows.Forms.Form
{
public AppForm2()
{
this.Size = new System.Drawing.Size(300, 300);
this.Text = "AppForm2";
}
}
// A simple form that represents a window in our application
public class AppForm1 : System.Windows.Forms.Form
{
public AppForm1()
{
this.Size = new System.Drawing.Size(300, 300);
this.Text = "AppForm1";
}
}
// The class that handles the creation of the application windows
class MyApplicationContext : ApplicationContext
{
private int _formCount;
private AppForm1 _form1;
private AppForm2 _form2;
private Rectangle _form1Position;
private Rectangle _form2Position;
private FileStream _userData;
private MyApplicationContext()
{
_formCount = 0;
// Handle the ApplicationExit event to know when the application is exiting.
Application.ApplicationExit += new EventHandler(this.OnApplicationExit);
try
{
// Create a file that the application will store user specific data in.
_userData = new FileStream(Application.UserAppDataPath + "\\appdata.txt", FileMode.OpenOrCreate);
}
catch (IOException e)
{
// Inform the user that an error occurred.
MessageBox.Show("An error occurred while attempting to show the application." +
"The error is:" + e.ToString());
// Exit the current thread instead of showing the windows.
ExitThread();
}
// Create both application forms and handle the Closed event
// to know when both forms are closed.
_form1 = new AppForm1();
_form1.Closed += new EventHandler(OnFormClosed);
_form1.Closing += new CancelEventHandler(OnFormClosing);
_formCount++;
_form2 = new AppForm2();
_form2.Closed += new EventHandler(OnFormClosed);
_form2.Closing += new CancelEventHandler(OnFormClosing);
_formCount++;
// Get the form positions based upon the user specific data.
if (ReadFormDataFromFile())
{
// If the data was read from the file, set the form
// positions manually.
_form1.StartPosition = FormStartPosition.Manual;
_form2.StartPosition = FormStartPosition.Manual;
_form1.Bounds = _form1Position;
_form2.Bounds = _form2Position;
}
// Show both forms.
_form1.Show();
_form2.Show();
}
private void OnApplicationExit(object sender, EventArgs e)
{
// When the application is exiting, write the application data to the
// user file and close it.
WriteFormDataToFile();
try
{
// Ignore any errors that might occur while closing the file handle.
_userData.Close();
}
catch { }
}
private void OnFormClosing(object sender, CancelEventArgs e)
{
// When a form is closing, remember the form position so it
// can be saved in the user data file.
if (sender is AppForm1)
_form1Position = ((Form)sender).Bounds;
else if (sender is AppForm2)
_form2Position = ((Form)sender).Bounds;
}
private void OnFormClosed(object sender, EventArgs e)
{
// When a form is closed, decrement the count of open forms.
// When the count gets to 0, exit the app by calling
// ExitThread().
_formCount--;
if (_formCount == 0)
{
ExitThread();
}
}
private bool WriteFormDataToFile()
{
// Write the form positions to the file.
UTF8Encoding encoding = new UTF8Encoding();
RectangleConverter rectConv = new RectangleConverter();
string form1pos = rectConv.ConvertToString(_form1Position);
string form2pos = rectConv.ConvertToString(_form2Position);
byte[] dataToWrite = encoding.GetBytes("~" + form1pos + "~" + form2pos);
try
{
// Set the write position to the start of the file and write
_userData.Seek(0, SeekOrigin.Begin);
_userData.Write(dataToWrite, 0, dataToWrite.Length);
_userData.Flush();
_userData.SetLength(dataToWrite.Length);
return true;
}
catch
{
// An error occurred while attempting to write, return false.
return false;
}
}
private bool ReadFormDataFromFile()
{
// Read the form positions from the file.
UTF8Encoding encoding = new UTF8Encoding();
string data;
if (_userData.Length != 0)
{
byte[] dataToRead = new byte[_userData.Length];
try
{
// Set the read position to the start of the file and read.
_userData.Seek(0, SeekOrigin.Begin);
_userData.Read(dataToRead, 0, dataToRead.Length);
}
catch (IOException e)
{
string errorInfo = e.ToString();
// An error occurred while attempt to read, return false.
return false;
}
// Parse out the data to get the window rectangles
data = encoding.GetString(dataToRead);
try
{
// Convert the string data to rectangles
RectangleConverter rectConv = new RectangleConverter();
string form1pos = data.Substring(1, data.IndexOf("~", 1) - 1);
_form1Position = (Rectangle)rectConv.ConvertFromString(form1pos);
string form2pos = data.Substring(data.IndexOf("~", 1) + 1);
_form2Position = (Rectangle)rectConv.ConvertFromString(form2pos);
return true;
}
catch
{
// Error occurred while attempting to convert the rectangle data.
// Return false to use default values.
return false;
}
}
else
{
// No data in the file, return false to use default values.
return false;
}
}
[STAThread]
static void Main(string[] args)
{
// Create the MyApplicationContext, that derives from ApplicationContext,
// that manages when the application should exit.
MyApplicationContext context = new MyApplicationContext();
// Run the application with the specific context. It will exit when
// all forms are closed.
Application.Run(context);
}
}
}
Imports System.Drawing
Imports System.Windows.Forms
Imports System.ComponentModel
Imports System.Text
Imports System.IO
' A simple form that represents a window in our application
Public Class AppForm1
Inherits System.Windows.Forms.Form
Public Sub New()
MyBase.New()
Me.Size = New System.Drawing.Size(300, 300)
Me.Text = "AppForm1"
End Sub
End Class
' A simple form that represents a window in our application
Public Class AppForm2
Inherits System.Windows.Forms.Form
Public Sub New()
MyBase.New()
Me.Size = New System.Drawing.Size(300, 300)
Me.Text = "AppForm2"
End Sub
End Class
' The class that handles the creation of the application windows
Public Class MyApplicationContext
Inherits ApplicationContext
Private _formCount As Integer
Private _form1 As AppForm1
Private _form2 As AppForm2
Private _form1Position As Rectangle
Private _form2Position As Rectangle
Private _userData As FileStream
Public Sub New()
MyBase.New()
_formCount = 0
' Handle the ApplicationExit event to know when the application is exiting.
AddHandler Application.ApplicationExit, AddressOf OnApplicationExit
Try
' Create a file that the application will store user specific data in.
_userData = New FileStream(Application.UserAppDataPath + "\appdata.txt", FileMode.OpenOrCreate)
Catch e As IOException
' Inform the user that an error occurred.
MessageBox.Show("An error occurred while attempting to show the application." +
"The error is:" + e.ToString())
' Exit the current thread instead of showing the windows.
ExitThread()
End Try
' Create both application forms and handle the Closed event
' to know when both forms are closed.
_form1 = New AppForm1()
AddHandler _form1.Closed, AddressOf OnFormClosed
AddHandler _form1.Closing, AddressOf OnFormClosing
_formCount = _formCount + 1
_form2 = New AppForm2()
AddHandler _form2.Closed, AddressOf OnFormClosed
AddHandler _form2.Closing, AddressOf OnFormClosing
_formCount = _formCount + 1
' Get the form positions based upon the user specific data.
If (ReadFormDataFromFile()) Then
' If the data was read from the file, set the form
' positions manually.
_form1.StartPosition = FormStartPosition.Manual
_form2.StartPosition = FormStartPosition.Manual
_form1.Bounds = _form1Position
_form2.Bounds = _form2Position
End If
' Show both forms.
_form1.Show()
_form2.Show()
End Sub
Private Sub OnApplicationExit(ByVal sender As Object, ByVal e As EventArgs)
' When the application is exiting, write the application data to the
' user file and close it.
WriteFormDataToFile()
Try
' Ignore any errors that might occur while closing the file handle.
_userData.Close()
Catch
End Try
End Sub
Private Sub OnFormClosing(ByVal sender As Object, ByVal e As CancelEventArgs)
' When a form is closing, remember the form position so it
' can be saved in the user data file.
If TypeOf sender Is AppForm1 Then
_form1Position = CType(sender, Form).Bounds
ElseIf TypeOf sender Is AppForm2 Then
_form2Position = CType(sender, Form).Bounds
End If
End Sub
Private Sub OnFormClosed(ByVal sender As Object, ByVal e As EventArgs)
' When a form is closed, decrement the count of open forms.
' When the count gets to 0, exit the app by calling
' ExitThread().
_formCount = _formCount - 1
If (_formCount = 0) Then
ExitThread()
End If
End Sub
Private Function WriteFormDataToFile() As Boolean
' Write the form positions to the file.
Dim encoding As UTF8Encoding = New UTF8Encoding()
Dim rectConv As RectangleConverter = New RectangleConverter()
Dim form1pos As String = rectConv.ConvertToString(_form1Position)
Dim form2pos As String = rectConv.ConvertToString(_form2Position)
Dim dataToWrite As Byte() = encoding.GetBytes("~" + form1pos + "~" + form2pos)
Try
' Set the write position to the start of the file and write
_userData.Seek(0, SeekOrigin.Begin)
_userData.Write(dataToWrite, 0, dataToWrite.Length)
_userData.Flush()
_userData.SetLength(dataToWrite.Length)
Return True
Catch
' An error occurred while attempting to write, return false.
Return False
End Try
End Function
Private Function ReadFormDataFromFile() As Boolean
' Read the form positions from the file.
Dim encoding As UTF8Encoding = New UTF8Encoding()
Dim data As String
If (_userData.Length <> 0) Then
Dim dataToRead(_userData.Length) As Byte
Try
' Set the read position to the start of the file and read.
_userData.Seek(0, SeekOrigin.Begin)
_userData.Read(dataToRead, 0, dataToRead.Length)
Catch e As IOException
Dim errorInfo As String = e.ToString()
' An error occurred while attempt to read, return false.
Return False
End Try
' Parse out the data to get the window rectangles
data = encoding.GetString(dataToRead)
Try
' Convert the string data to rectangles
Dim rectConv As RectangleConverter = New RectangleConverter()
Dim form1pos As String = data.Substring(1, data.IndexOf("~", 1) - 1)
_form1Position = CType(rectConv.ConvertFromString(form1pos), Rectangle)
Dim form2pos As String = data.Substring(data.IndexOf("~", 1) + 1)
_form2Position = CType(rectConv.ConvertFromString(form2pos), Rectangle)
Return True
Catch
' Error occurred while attempting to convert the rectangle data.
' Return false to use default values.
Return False
End Try
Else
' No data in the file, return false to use default values.
Return False
End If
End Function
End Class
Public Module MyApplication
Public Sub Main()
' Create the MyApplicationContext, that derives from ApplicationContext,
' that manages when the application should exit.
Dim context As MyApplicationContext = New MyApplicationContext()
' Run the application with the specific context. It will exit when
' all forms are closed.
Application.Run(context)
End Sub
End Module
È possibile usare la classe per ridefinire le circostanze che causano l'uscita ApplicationContext di un ciclo di messaggi. Per impostazione predefinita, l'evento ApplicationContext è in ascolto dell'evento Closed nel main Formdell'applicazione e quindi chiude il ciclo di messaggi del thread.
Application |
Inizializza una nuova istanza della classe ApplicationContext senza contesto. |
Application |
Inizializza una nuova istanza della classe ApplicationContext con l'oggetto Form specificato. |
Main |
Ottiene o imposta il Form da utilizzare come contesto. |
Tag |
Ottiene o imposta un oggetto che contiene i dati relativi al controllo. |
Dispose() |
Rilascia tutte le risorse usate da ApplicationContext. |
Dispose(Boolean) |
Rilascia le risorse non gestite usate da ApplicationContext e, facoltativamente, le risorse gestite. |
Equals(Object) |
Determina se l'oggetto specificato è uguale all'oggetto corrente. (Ereditato da Object) |
Exit |
Termina il ciclo di messaggi del thread. |
Exit |
Termina il ciclo di messaggi del thread. |
Finalize() |
Tenta di liberare risorse ed eseguire altre operazioni di pulitura prima che il contesto dell'applicazione venga recuperato dalla procedura di Garbage Collection. |
Get |
Funge da funzione hash predefinita. (Ereditato da Object) |
Get |
Ottiene l'oggetto Type dell'istanza corrente. (Ereditato da Object) |
Memberwise |
Crea una copia superficiale dell'oggetto Object corrente. (Ereditato da Object) |
On |
Chiama il metodo ExitThreadCore(), che genera l'evento ThreadExit. |
To |
Restituisce una stringa che rappresenta l'oggetto corrente. (Ereditato da Object) |
Thread |
Viene generato quando il ciclo di messaggi del thread deve essere terminato, chiamando il metodo ExitThread(). |
Prodotto | Versioni |
---|---|
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
Windows Desktop | 3.0, 3.1, 5, 6, 7, 8, 9 |
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