请教高手C#中BackGroundWorker的详细使用方法以及如何正确高效访问父窗体UI方法

huating008 2009-04-07 07:06:09

各位高手大哥大姐们，我是已在读的学生，最近自己筹划着写了个winform小程序，在编写一个和BackGroundWorker使用有关的代码段时出现了问题。我程序设计的总体思路是：在一个子窗体载入事件Page_Load中调用backGroundWorker1.RunAysnc()启动BackGroundWorker，之后及启动的代码如下：
private void FrmPrintBalance_Load(object sender, EventArgs e)
{
Cursor.Current = System.Windows.Forms.Cursors.AppStarting;
FrmMain parentFrm = (FrmMain)this.MdiParent;
parentFrm.timer1.Stop();
parentFrm.toolstateDate.Text = "收支汇总报表正在载入中．．．";
parentFrm.toolStripProgressBar2.Visible = true;
if (!backgroundWorker1.IsBusy)
{
backgroundWorker1.RunWorkerAsync(); //启动BackGroundWorker
}
}

private delegate void DoWorkCallBack();
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
Thread myTread = new Thread(new ThreadStart(StartDoWork));
myTread.Start();

}
private void StartDoWork() //若要操作UI,只有DoWork中需要借助Invoke，其他两个不用
{
if (this.InvokeRequired)
{
DoWorkCallBack dwc = new DoWorkCallBack(StartDoWork);
this.Invoke(dwc);
}
else
{
this.tb_FamilyBalanceTableAdapter1.Fill(this.financialMISDataSet_tb_FamilyBalance1.tb_FamilyBalance);
CrystalReportFamilyBalance1.SetDataSource(this.financialMISDataSet_tb_FamilyBalance1); //给水晶报表填充数据
}
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
FrmMain parentForm = (FrmMain)this.MdiParent;
parentForm.toolStripProgressBar2.Value = e.ProgressPercentage;

}

private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
FrmMain parentForm = (FrmMain)this.MdiParent;
parentForm.toolstateDate.Text = "收支汇总报表载入完成";
parentForm.toolStripProgressBar2.Visible = false;
parentForm.timer1.Start();
}

可是不知什么原因，调试时总是在“this.Invoke(dwc)"处报“未将对像实例化”，另外觉得好像缺个启动backgroundWorker1_ProgressChanged（）的ReportProgress（）调用。

这个应用的确有点麻烦和复杂，涉及到了BackGroundWorker和访问父窗体UI控件的综合应用。正是因为这样，才是它具有一定挑战性！烦请各位高手慷慨解囊，小弟在这里先谢谢了！

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