2

我想知道您建议使用什么方法来避免我的表单在执行存储过程时挂起。请参阅我附加的代码。我正在通过 Stream API 从 Twitter 收集数据,并且在执行存储过程时表单挂起。使用 BackgroundWorker 是避免表单挂起的最佳方法吗?你能给我一个例子,这是如何在我的代码中实现的。

Imports System.Linq
Imports System.Text
Imports System.Net
Imports System.IO
Imports Newtonsoft.Json.Linq
Imports Newtonsoft.Json
Imports System.Data.SqlClient
Imports System.Threading

Public Class Form1

    Private Sub btnDB_Click(sender As System.Object, e As System.EventArgs) Handles btnDB.Click
        Dim url As String = "https://stream.twitter.com/1.1/statuses/filter.json?track=twitter"
        Dim request As WebRequest = WebRequest.Create(url)
        request.Credentials = New NetworkCredential("username", "pwd")
        Dim WebResponse = request.GetResponse()
        Dim encode As Encoding = Encoding.GetEncoding("utf-8")
        Dim responseStrem = New StreamReader(WebResponse.GetResponseStream(), encode)




        While Not responseStrem.EndOfStream
            'Console.WriteLine(responseStrem.ReadLine());

            Dim json As String = responseStrem.ReadLine()
            If json.Length <> 0 Then
                ParseJson(json)
            End If
        End While
    End Sub

    Private Sub ParseJson(ByVal Json As String)

        Dim connectionstring As String = "Data Source=.;Initial Catalog=db_twitter_stream;User ID=sa;Password=xxx"
        Dim counter As Integer = 0
        Dim conn As New SqlConnection(connectionstring)
        conn.Open()
        Dim o As JObject = JObject.Parse(json)

        Dim tweet As String = o("text")
        Dim source As String = o("source")
        Dim created_at As String = o("created_at")

        Dim cmd As New SqlCommand("dbo.prc_tweets", conn)
        cmd.CommandType = System.Data.CommandType.StoredProcedure
        cmd.Parameters.Add(New SqlParameter("@tweet", tweet))
        cmd.Parameters.Add(New SqlParameter("@source", source))
        cmd.Parameters.Add(New SqlParameter("@created_at", created_at))

        cmd.ExecuteNonQuery()

        counter = counter + 1
        lblCount.Text = counter.ToString()



        conn.Close()

    End Sub

    Private Sub btnQuit_Click(sender As System.Object, e As System.EventArgs) Handles btnQuit.Click
        Me.Close()
    End Sub



End Class
4

1 回答 1

0

您的表单挂起,因为您正在主线程中运行代码。主线程负责响应鼠标点击、显示输出和循环获取输入。但是一旦你让主线程沉迷于其他事情,它在执行你的代码时就不能再运行它的所有任务,这会让你的表单看起来像是卡住了。您需要为更大的任务创建另一个线程。您需要使用 System.Threading 类中的线程池或更多过程。创建一个像 Private Sub 这样的 sub 并将其命名,然后将所有繁忙的代码放入其中,并以 End Sub 结束 sub。然后创建一个线程变量并将其寻址到该 Sub。Dim variable As New System.Threading.Thread(AddressOf yoursubnamehere). 然后设置它的属性,如优先级等。然后threadvariable.Start()。问题已解决:) 如果对您更方便,您也可以使用 backgroundworker。

于 2013-12-25T22:37:37.777 回答