Invoke, Thread, VB.net

VB.net Thread執行序簡單應用

  • 透過本範例，將耗時的工作挪到背景另外執行，如:資料庫搜尋、Socket連線傳輸等

建立一個Class用來執行新的Thread

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Imports System.Threading

Namespace Classes
	Public Class Worker
		Delegate Sub WorkerDelegate(ByVal Params As Object)
		Private m_Thread As Thread = Nothing
		Private m_Controler As Control = Nothing
		Private m_Params As Object = Nothing
		Public Event WorkerToDo(ByRef Params As Object)
		Public Event WorkerInvoke(ByVal Params As Object)
		Dim CallBackInvoke As New WorkerDelegate(AddressOf Worker_Invoke)

		Public Sub New(ByVal ctrl As Control)
			m_Controler = ctrl
		End Sub

		Public Sub Start()
			Dim ThreadBegin As New ThreadStart(AddressOf Worker_ToDo)
			Me.m_Thread = New Thread(ThreadBegin)
			Me.m_Thread.IsBackground = True
			Me.m_Thread.Name = "WorkerThread" + Now.ToShortTimeString()
			Me.m_Thread.Start()
		End Sub

		Private Sub Worker_ToDo()
			RaiseEvent WorkerToDo(m_Params)
			m_Controler.Invoke(CallBackInvoke, m_Params)
		End Sub

		Private Sub Worker_Invoke(ByVal Params As Object)
			RaiseEvent WorkerInvoke(Params)
		End Sub
	End Class
End Namespace

使用方式

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Private Sub LoadData()
	Dim wk As New Worker(Me)
	Try
		'連結要丟到背景工作的副程式
		AddHandler wk.WorkerToDo, AddressOf DoQueryDataBase
		'工作完畢後, 所要處理資料(與UI互動)
		AddHandler wk.WorkerInvoke, AddressOf BindData
		wk.Start()
	Finally
		wk = Nothing
	End Try
End Sub

Private Sub DoQueryDataBase(ByRef Params As Object)
	'執行的程式, 結果可由 Params 代傳
	'1: Params = modADO.Query(...)
	'2: Params = New Object() {data1, data2, ...}	
End Sub

Private Sub BindData(ByVal Params As Object)
	'背景工作完畢後, 與 UI 互動
	TextBox1.Text = CInt(Params)
End Sub