vb.net多线程同步调用实例

以前一直感觉多线程比较难懂，最近由于需要，没办法必须克服，这不看了几遍书，终于理解差不多了，先把最开始的一个实例弄上来吧。

Imports System.Threading   '看名字就知道，这个类干什么用的，多线程应用程序都要用这个类

Public Delegate Function BinaryOp(ByVal x As Integer, ByVal y As Integer) As Integer

Module Module1

    Sub Main()

        Console.WriteLine("***** Synch Delegate Review *****")

        ' Print out the ID of the executing thread.

        Console.WriteLine("Main() invoked on thread {0}.", Thread.CurrentThread.ManagedThreadId)

        ' Invoke Add() in a synchronous manner.

        Dim b As New BinaryOp(AddressOf Add)

        ' Could also write b. Invoke(10, 10);   注意区别 同步方式是invoke,已不是beginInvoke

        Dim answer As Integer = b(10, 10)

        ' These lines will not execute until

        ' the Add() method has completed.

        Console.WriteLine("Doing more work in Main()!")

        Console.WriteLine("10 + 10 is {0}.", answer)

        Console.ReadLine()

    End Sub

    Private Function Add(ByVal x As Integer, ByVal y As Integer) As Integer

        ' Print out the ID of the executing thread.

        Console.WriteLine("Add() invoked on thread {0}.", Thread.CurrentThread.ManagedThreadId)

        ' Pause to simulate a lengthy operation.

        Thread.Sleep(5000)

        Return x + y

    End Function

End Module

不知道大家怎么理解这个同步和异步。反正这个不大好理解,我觉得主要就看是否有阻塞或者尽可能小的阻塞。特别是同步调用方式和同步调用线程的区别，特别是很多翻译过来的东西，最好还是看原文和实例。

---------------------------一以下异步调用代码----------------------------------------------------

Imports System.Threading  '看名字就知道，这个类干什么用的，多线程应用程序都要用这个类

Public Delegate Function BinaryOp(ByVal x As Integer, ByVal y As Integer) As Integer

Module Module1

    Sub main()

        Console.WriteLine("***** Async Delegate Invocation *****")

        ' Print out the ID of the executing thread.

        Console.WriteLine("Main() invoked on thread {0}.", Thread.CurrentThread.ManagedThreadId)

        Dim b As New BinaryOp(AddressOf Add)

        Dim iftAR As IAsyncResult = b.BeginInvoke(10, 10, Nothing, Nothing)

        ' This message will keep printing until

        ' the Add() method is finished.

        Do While Not iftAR.IsCompleted  

            Console.WriteLine("Doing more work in Main()!")

            Thread.Sleep(1000)

        Loop

        ' Now we know the Add() method is complete.

        Dim answer As Integer = b.EndInvoke(iftAR)

        Console.WriteLine("10 + 10 is {0}.", answer)

        Console.ReadLine()

    End Sub

    Private Function Add(ByVal x As Integer, ByVal y As Integer) As Integer

        ' Print out the ID of the executing thread.

        Console.WriteLine("Add() invoked on thread {0}.", Thread.CurrentThread.ManagedThreadId)

        ' Pause to simulate a lengthy operation.

        Thread.Sleep(5000)

        Return x + y

    End Function

End Module