StateChangeEventArgs StateChangeEventArgs StateChangeEventArgs StateChangeEventArgs Class

Определение

Предоставляет данные для события изменения состояния поставщика данных .NET Framework.Provides data for the state change event of a .NET Framework data provider.

public ref class StateChangeEventArgs sealed : EventArgs
public sealed class StateChangeEventArgs : EventArgs
type StateChangeEventArgs = class
    inherit EventArgs
Public NotInheritable Class StateChangeEventArgs
Inherits EventArgs
Наследование
StateChangeEventArgsStateChangeEventArgsStateChangeEventArgsStateChangeEventArgs

Примеры

В следующем примере показано, как использовать StateChange события в SqlConnection класса.The following example shows how to use the StateChange event within the SqlConnection class.

// Handler for OnStateChange event.
protected static void OnStateChange(object sender,
    StateChangeEventArgs e)
{
    PrintEventArgs(e);
}

static void Main()
{
    FillDataSet();
}

static private void FillDataSet()
{
    string connectionString = GetConnectionString();
    string queryString =
        "SELECT ProductID, UnitPrice from dbo.Products;";

    // Create a DataAdapter.
    using (SqlDataAdapter dataAdapter =
               new SqlDataAdapter(queryString, connectionString))
    {

        // Add the handlers.
        dataAdapter.SelectCommand.Connection.StateChange
            += new StateChangeEventHandler(OnStateChange);

        // Create a DataSet.
        DataSet dataSet = new DataSet();

        // Fill the DataSet, which fires several StateChange events.
        dataAdapter.Fill(dataSet, 0, 5, "Table");
    }
}

protected static void PrintEventArgs(StateChangeEventArgs args)
{
    Console.WriteLine("StateChangeEventArgs");
    Console.WriteLine("  OriginalState= {0} CurrentState= {1}",
        args.OriginalState, args.CurrentState);
}

static private string GetConnectionString()
{
    // To avoid storing the connection string in your code, 
    // you can retrieve it from a configuration file.
    return "Data Source=(local);Initial Catalog=Northwind;"
        + "Integrated Security=true";
}
' Handler for the OnStateChange event.
Private Sub OnStateChange(ByVal sender As Object, _
    ByVal e As StateChangeEventArgs)
    PrintEventArgs(e)
End Sub

Sub Main()
    FillDataSet()
End Sub

Private Sub FillDataSet()
    Dim connectionString As String = GetConnectionString()
    Dim queryString As String = _
        "SELECT ProductID, UnitPrice from dbo.Products;"

    ' Create a DataAdapter.
    Using dataAdapter As New SqlDataAdapter( _
        queryString, connectionString)

        ' Add the handlers.
        AddHandler dataAdapter.SelectCommand.Connection.StateChange, _
            AddressOf OnStateChange

        ' Create a DataSet.
        Dim dataSet As New DataSet()

        ' Fill the DataSet, which fires several StateChange events.
        dataAdapter.Fill(dataSet, 0, 5, "Table")
    End Using
End Sub

Private Sub PrintEventArgs(ByVal args As StateChangeEventArgs)
    Console.WriteLine("StateChangeEventArgs")
    Console.WriteLine("  OriginalState= {0} CurrentState= {1}", _
        args.OriginalState, args.CurrentState)
End Sub

Private Function GetConnectionString() As String
    ' To avoid storing the connection string in your code,  
    ' you can retrieve it from a configuration file.
    Return "Data Source=(local);Initial Catalog=Northwind;" _
       & "Integrated Security=true;"
End Function

Комментарии

Данные используются при StateChange свойство OleDbConnection и StateChange свойство SqlConnection.The data is used by the StateChange property of the OleDbConnection and the StateChange property of the SqlConnection.

Конструкторы

StateChangeEventArgs(ConnectionState, ConnectionState) StateChangeEventArgs(ConnectionState, ConnectionState) StateChangeEventArgs(ConnectionState, ConnectionState) StateChangeEventArgs(ConnectionState, ConnectionState)

Инициализирует новый экземпляр класса StateChangeEventArgs при данном исходном и текущем состоянии объекта.Initializes a new instance of the StateChangeEventArgs class, when given the original state and the current state of the object.

Свойства

CurrentState CurrentState CurrentState CurrentState

Получает новое состояние подключения.Gets the new state of the connection. Объект подключения будет уже в новом состоянии, когда событие запущено.The connection object will be in the new state already when the event is fired.

OriginalState OriginalState OriginalState OriginalState

Получает текущее состояние подключения.Gets the original state of the connection.

Методы

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Определяет, равен ли заданный объект текущему объекту.Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Служит хэш-функцией по умолчанию.Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

Возвращает объект Type для текущего экземпляра.Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Создает неполную копию текущего объекта Object.Creates a shallow copy of the current Object.

(Inherited from Object)
ToString() ToString() ToString() ToString()

Возвращает строку, представляющую текущий объект.Returns a string that represents the current object.

(Inherited from Object)

Применяется к