Question

基本上我要做的是当应用程序运行时我开始更新股票报价并每隔10秒启动一个计时器（10000毫秒）它将10加到整数变量，间隔为60秒并且我想要一个标签在＆＃34;中显示＆＃34;下一次更新在达到分钟后每隔10秒标记一次我希望更新股票报价并重置计时器再次执行此操作，只要程序打开，这将始终运行。

这是我的代码到目前为止，它会跳过if语句，因为当它到达该语句并退出时它不会在10秒内完成。我应该使用do while循环吗？

Imports System.Net
Imports System.IO
Imports Newtonsoft.Json

Public Class Form1

Private Symbols As List(Of String) = Nothing
Private Prices() As List(Of String) = Nothing
Private secondCount As Integer
Private intervalCount As Integer = 60
' force Update
Private Sub forceUpdateBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles forceUpdateBtn.Click
    QuoteUpdater()
End Sub

Public Function GetStockPrices(symbol As String) As List(Of String)
    ' Dim pricesArray() As String
    Dim prices As New List(Of String)()
    Dim items() As GoogleFinanceItem

    If UCase(symbol) = "INDU" Then
        Dim url As String = "http://finance.google.com/finance/info?client=ig&q=INDEXDJX%3A.DJI"
        Dim result As String = GetWebResponse(url).Replace("//", "")
        '  Dim newResult = result.Remove(0, 3)
        items = JsonConvert.DeserializeObject(Of GoogleFinanceItem())(result)
        '  pricesArray = Split(result, ":")
    Else
        Dim url As String = "http://finance.google.com/finance/info?client=ig&q=" & UCase(symbol)
        Dim result As String = GetWebResponse(url).Replace("//", "")
        ' Dim newResult = result.Remove(0, 3)
        items = JsonConvert.DeserializeObject(Of GoogleFinanceItem())(result)
        '   pricesArray = Split(result, ":")
    End If
    '   pricesArray = Split(pricesArray(4), """")

    '    prices.Add(CSng(Format(pricesArray(1), "0.00")))
    'prices.Add(CSng(Format(pricesArray(1))))
    prices.Add(items(0).price)
    Return prices

End Function

' Get a web response.
Private Function GetWebResponse(ByVal url As String) As String
    ' Make a WebClient.
    Dim web_client As New WebClient()

    ' Get the indicated URL.
    Dim response As Stream = web_client.OpenRead(url)

    ' Read the result.
    Using stream_reader As New StreamReader(response)
        ' Get the results.
        Dim result As String = stream_reader.ReadToEnd()

        ' Close the stream reader and its underlying stream.
        stream_reader.Close()

        ' Return the result.
        Return result
    End Using
End Function

Private Sub FillData()
    Dim symbolSubSet() As Control = {Label1, Label2, Label3}
    Dim priceSubSet() As Control = {Label4, Label5, Label6}
    For i = 0 To 2
        symbolSubSet(i).Text = Symbols(i)
        priceSubSet(i).Text = Prices(i)(0)   'collection inside a collection. so in the first spot the array is in
    Next
    statusLbl.Text = "Last Updated: " + Now.ToString
End Sub


Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load, updateTimer.Tick
    QuoteUpdater()
    updateTimer.Start()

    If updateTimer.Interval = 10000 Then
        secondCount = secondCount + 10
        nextUpdateLbl.Text = "in " + CStr(intervalCount - secondCount) + " secs"
    End If

End Sub

Private Sub exitBtn_Click(sender As Object, e As EventArgs) Handles exitBtn.Click
    Application.Exit()
End Sub



Private Sub QuoteUpdater()
    Me.Cursor = Cursors.WaitCursor

    ' Get the ticker symbols.
    'Dim symbols_text() As String = txtSymbols.Text.Split(","c)
    Dim symbols_text() As String = {"PKG", "TEN", "INDU"}
    Symbols = New List(Of String)()
    For i As Integer = 0 To symbols_text.Length - 1
        Symbols.Add(symbols_text(i).Trim())
    Next i

    ' Get the data.
    ReDim Prices(0 To Symbols.Count - 1)
    For i As Integer = 0 To Symbols.Count - 1
        Prices(i) = GetStockPrices(Symbols(i))
    Next i

    ' Graph it.
    'DrawGraph()
    FillData()
    Me.Cursor = Cursors.Default
End Sub



End Class

Answer 1

计时器间隔不会随着时间的推移而改变，因此除非您更改间隔，否则If updateTimer.Interval = 10000...将始终为真。因为你想每10秒钟做一件事，每分钟做一件事，这只意味着你想要做6次不同的事情。

Private Counter As Int32 = 6
Private Sub updateTimer_Tick(... Handles updateTimer.Tick

        Counter += 1
        If Counter < 6 Then
            lblNext.Text = String.Format("Next Update in {0} secs", (6 - Counter) * 10)
            ' "early exit"
            Return
        End If

        ' stuff to do on the minute
        updateTimer.Stop()
        QuoteUpdater()
        lblNext.Text = "Next Update in 1 minute"

        Counter = 1
        updateTimer.Start()
End Sub
Private Sub Form1_Load(...) Handles MyBase.Load
    ' do one time only things like initializing objects and collections
    ...
    lblNext.Text = "First update in 10 secs"
    updateTimer.Interval = 10000
    updateTimer.Enabled = True
End Sub

代码只计算已经过了多少个间隔，并在计数达到6时进行更新。更新后，它会重置计数器。

我将FormLoad和Tick事件分开了。通过将Counter初始化为6，它允许第一次更新发生在第一个Tick上。这将允许您在FormLoad中执行只需要执行一次的操作。它还可以改善表单在第一次加载时的外观，因为在进行引用相关的操作之前，它有时间绘制所有内容。

你也可能想重新考虑“在XX秒内进行下一次更新”的想法，因为如果剩下1或9秒，它会说同样的事情。也许打印下次更新的时间？

使用计时器每10秒做一件事，但每分钟做一次其他事情

1 个答案: