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

Question

      我是在读的学生，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。

Answer 1

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) { StartDoWork(); } private void StartDoWork() //若要操作UI,只有DoWork中需要借助Invoke，其他两个不用 { this.tb_FamilyBalanceTableAdapter1.Fill(this.financialMISDataSet_tb_FamilyBalance1.tb_FamilyBalance); } 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) { CrystalReportFamilyBalance1.SetDataSource(this.financialMISDataSet_tb_FamilyBalance1); //给水晶报表填充数据 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(); }

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知识改变命运，奋斗成就人生!

Answer 2

在RunWorker中获取数据,在RunWorkComplate中绑定报表就好了

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知识改变命运，奋斗成就人生!

Answer 3

你好！
     这一行似乎有问题，DoWorkCallBack dwc = new DoWorkCallBack(StartDoWork);
     怎么把这个函数本身指定给dwc了啊！

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周雪峰

Answer 4

这种委托是可以的， 我程序的其他部分就使用了，  经测试没出现过问题。

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华廷

Answer 5

补充：另外，不知怎么在DoWork事件处理函数中跟踪或获取水晶报表数据的载入进度以报告给ProgresChanged事件处理函数，请指教！

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华廷