批量处理任务进度条控制—基于BackgroundWorker

      今天要做一个批量处理图层数据的功能，希望在处理任务过程中，各个任务都能在进度条中显示自己的当前进度，决定继续使用强大易用的BackgroundWorker组件。通过在RunWorkerCompleted事件中进行控制来达到各任务独立显示完成进度的目标。测试在之前的介绍BackgroundWork功能的测试代码基础上展开，测试例子截图如下：

                                                  

分别向每个ListBox中写入1-100000的数字，向每个Listbox中写入过程中，进度条都自左向右走一遍，直到3个ListBox写入数字任务全部完成。代码如下：

 public partial class Form1 : Form
    {
        List<ListBox> m_NumberBoxList = new List<ListBox>();//存放ListBox
        ListBox m_CurrentListBox = null;//当前写入Items的ListBox
        int m_CurrentListBoxIndex = 0;//当前写入Items的ListBox的索引
        public Form1()
        {
            InitializeComponent();

            backgroundWorker1.WorkerReportsProgress = true;//报告完成进度 
            backgroundWorker1.WorkerSupportsCancellation = true;//允许用户终止后台线程 
            backgroundWorker1.DoWork += new DoWorkEventHandler(ListNumber);

            m_NumberBoxList.Add(listBox1);
            m_NumberBoxList.Add(listBox2);
            m_NumberBoxList.Add(listBox3);
        }

        private void btnOk_Click(object sender, EventArgs e)
        {
            //向第一个ListBox写入数值
            m_CurrentListBox = m_NumberBoxList[0];
            if (!backgroundWorker1.IsBusy)//判断backgroundWorker1是否正在运行异步操作 
            {
                backgroundWorker1.RunWorkerAsync(100000);//开始执行后台操作 
            } 
        }

        void ListNumber(object sender, DoWorkEventArgs e)
        {
            int num = (int)e.Argument;//接收传入的参数 
            for (int i = 1; i <= num; i++)
            {
                if (backgroundWorker1.CancellationPending)//判断是否请求了取消后台操作 
                {
                    e.Cancel = true;
                    return ;
                }
                backgroundWorker1.ReportProgress(i * 100 / num, i);//报告完成进度 
                System.Threading.Thread.Sleep(0);//后台线程交出时间片 
            }
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            progressBar1.Value = e.ProgressPercentage;//将完成进度数据传给进度条 
            m_CurrentListBox.Items.Add(e.UserState);//将中间计算结果在ListBox控件中显示出来 
            m_CurrentListBox.Update();//刷新ListBox
        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            progressBar1.Value = 0;
            m_CurrentListBoxIndex++;

            if(m_CurrentListBoxIndex!=m_NumberBoxList.Count)
            {
                m_CurrentListBox = m_NumberBoxList[m_CurrentListBoxIndex];
                if (!backgroundWorker1.IsBusy)//判断backgroundWorker1是否正在运行异步操作 
                { 
                    backgroundWorker1.RunWorkerAsync(100000);//开始执行后台操作 
                } 
            }
            else 
            {
                m_CurrentListBoxIndex = 0;
                MessageBox.Show("处理完成！");
            }
        }

        private void btnStop_Click(object sender, EventArgs e)
        {
            if (backgroundWorker1.WorkerSupportsCancellation == true)
            {
                backgroundWorker1.CancelAsync();//取消后台操作 
                backgroundWorker1.Dispose();//释放资源 
            }
        }
    }

运行过程截图如下：