C＃中长时间运行任务的进度条

Question

我的应用程序运行一些数据库查询，这可能需要很长时间。

在执行这些查询时，我的应用程序似乎死机了，看起来该应用程序已停止工作。

我需要使用progressbar来避免此问题，但是我不确定如何预测查询执行所花费的时间。

运行查询的代码如下

private void CheckSsMissingDate()
 {
  while (DateTime.Parse(time) <= DateTime.Now)
   {
     var ssCon = OpenSQLConnection();
     var cmd = new SqlCommand("SELECT TOP (1)Date_Time,Value1,Value2,Value3,Value4,Value5,Value6,
         "+ "Value7,Value8,Value9 from RAW_S001T01 where Date_Time >='" + tempTime + "'",ssCon);
     var dr = cmd.ExecuteReader();
     var count = 0;
     while (dr.Read())
      {
        ssChkDate = (dr["Date_Time"].ToString());
        conssChkDate = DateTime.Parse(ssChkDate).ToString("yyyy-MM-dd HH:mm:ss");
        tempTime = Convert.ToDateTime(ssChkDate);
        tempTime = tempTime.AddMinutes(15);
        TValue1 = (dr["Value1"].ToString());
        TValue2 = (dr["Value2"].ToString());
        TValue3 = (dr["Value3"].ToString());
        TValue4 = (dr["Value4"].ToString());
        TValue5 = (dr["Value5"].ToString());
        TValue6 = (dr["Value6"].ToString());
        TValue7 = (dr["Value7"].ToString());
        TValue8 = (dr["Value8"].ToString());
        TValue9 = (dr["Value9"].ToString());
        if (CheckMsMissingDate(conssChkDate) == false)
          {
            InsertMissing(conssChkDate,TValue1,TValue2,TValue3,TValue4,TValue5,TValue6,TValue7,TValue8,TValue9);
                    count = count + 1;
           }
        }
       dr.Close();
       ssCon.Close();
       updateCount.Text = count + @" Missing Records added.";
    }
}

如何显示进度条以显示查询的进度？

Answer 1

您可以BackgroundWorker()用来解决这类问题。

首先定义一个类的全局变量，BackgroundWorker() 例如

private BackgroundWorker bgw;

然后在执行查询（如button1_Click()事件或其他任何内容）的过程中使用下面的代码。

bgw = new BackgroundWorker();
bgw.WorkerReportsProgress = true;
bgw.ProgressChanged += new ProgressChangedEventHandler(bgw_ProgressChanged);
bgw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgw_RunWorkerCompleted);
bgw.DoWork += new DoWorkEventHandler(bgw_DoWork);
bgw.RunWorkerAsync();

现在定义如下方法：

void bgw_DoWork(object sender, DoWorkEventArgs e)
 {
  //Your time taking work. Here it's your data query method.
  CheckSsMissingDate();
 }

void bgw_ProgressChanged(object sender, ProgressChangedEventArgs e)
 {
   //Progress bar.
   progressBar1.Value = e.ProgressPercentage;
 }

 void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
  {
   //After completing the job.
   MessageBox.Show(@"Finished");
  }