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c# 委托实现多线程的实例/另一个class类调用控件

admin3年前 (2021-09-27)C#3715

一、使用线程在窗体中显示进度条

在Winform应用程序中，经常用进度条显示进度信息。这时候就可能用到多线程。如果不采用多线程控制进度条的话，窗口界面很容易假死（无法看到进度信息，看起来像界面卡住了）。
在这个实例中，我们建立一个窗体，窗体中包括一个后台组件，一个进度条控件。当在主窗体中按“开始”按钮时，进度条开始显示进度。
该实例中用Backgroundworker组件，表示后台工作。通过后台工作组件实现进度条。
主窗体：

进度条窗体：

进度条窗体的代码如下：

    public partial class ProcessForm : Form
    {
        //后台操作
        private BackgroundWorker backgroundworker1;
        public ProcessForm(BackgroundWorker backgroundworker1)
        {
            InitializeComponent();
            this.backgroundworker1 = backgroundworker1;
            this.backgroundworker1.ProgressChanged += new ProgressChangedEventHandler(backgroundworker1_ProcessChanged);
            this.backgroundworker1.RunWorkerCompleted +=new RunWorkerCompletedEventHandler( Backgroundworker1_RunWorkerCompleted);
        }
        /// <summary>
        /// 当辅助线程完成时引发
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Backgroundworker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            this.Close();
        }

        private void backgroundworker1_ProcessChanged(object sender, ProgressChangedEventArgs e)
        {
            progressBar1.Value = e.ProgressPercentage;//异步任务的进度百分比

        }

        private void button1_Click(object sender, EventArgs e)
        {
            backgroundworker1.WorkerSupportsCancellation = true;
            backgroundworker1.CancelAsync();
            button1.Enabled = false;
            Close();
        }
    }

主窗体代码如下：

    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnBegin_Click(object sender, EventArgs e)
        {
            backgroundWorker1.RunWorkerAsync();//开始执行后台操作
            ProcessForm pf = new ProcessForm(backgroundWorker1);//显示进度条窗体，将后台程序传给进度条窗体
            pf.ShowDialog(this);
            pf.Close();
        }

        /// <summary>
        /// 当辅助线程完成时引发
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Error != null)
            {
                MessageBox.Show(e.Error.Message);
            }
        }

        /// <summary>
        /// 操作开始时在另一个线程上运行的事件处理程序
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            BackgroundWorker worker = sender as BackgroundWorker;
            for(int i=0;i<100;i++)
            {
                Thread.Sleep(100);
                worker.WorkerReportsProgress = true;
                worker.ReportProgress(i);
                if(worker.CancellationPending)
                {
                    e.Cancel = true;
                    break;
                }
            }
        }
    }

运行结果：

该例是通过后台程序组件完成对进度条的展示。
也可以在主窗体中通过后台组件完成进度条的显示，窗体设计如下：

代码如下：

    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnBegin_Click(object sender, EventArgs e)
        {
            backgroundWorker1.RunWorkerAsync();//开始执行后台操作

        }

        /// <summary>
        /// 当辅助线程完成时引发
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Error != null)
            {
                MessageBox.Show(e.Error.Message);
            }
            GC.Collect();
        }

        /// <summary>
        /// 操作开始时在另一个线程上运行的事件处理程序
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            BackgroundWorker worker = sender as BackgroundWorker;
            for(int i=0;i<101;i++)
            {
                Thread.Sleep(100);
                worker.WorkerReportsProgress = true;
                worker.ReportProgress(i);
                BeginInvoke(new Action(() =>
                {
                    label1.Text = progressBar1.Value.ToString();
                }));

                if(worker.CancellationPending)
                {
                    e.Cancel = true;
                    break;
                }
            }
            BeginInvoke(new Action(() =>
            {
                label1.Text = "完成";
            }));
        }
        /// <summary>
        /// 取消
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button1_Click(object sender, EventArgs e)
        {
            backgroundWorker1.WorkerSupportsCancellation = true;
            backgroundWorker1.CancelAsync();
            button1.Enabled = false;
            Close();
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            progressBar1.Value = e.ProgressPercentage;
        }
    }

运行结果如下：

二、实例二

功能说明：有时候在处理大量数据的时候，有时候方法的执行需要一定的时间，这时候往往会造成页面或程序的假死状态，对于用户的体验度也很不好。为了避免这种情况的发生，我们可以加一个进度条和一个文本框。来显示程序处理的进度。

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnBegin_Click(object sender, EventArgs e)
        {
            backgroundWorker1.RunWorkerAsync();//开始执行后台操作

        }

        /// <summary>
        /// 当辅助线程完成时引发
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Error != null)
            {
                MessageBox.Show(e.Error.Message);
            }
            GC.Collect();
        }

        /// <summary>
        /// 操作开始时在另一个线程上运行的事件处理程序
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            BackgroundWorker worker = sender as BackgroundWorker;
            for(int i=0;i<101;i++)
            {
                Thread.Sleep(100);
                //报告进度的属性设为true，允许报告进度
                worker.WorkerReportsProgress = true;
                worker.ReportProgress(i,i+"你好！\r\n");


                if(worker.CancellationPending)
                {
                    e.Cancel = true;
                    break;
                }
            }

        }
        /// <summary>
        /// 取消
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button1_Click(object sender, EventArgs e)
        {
            backgroundWorker1.WorkerSupportsCancellation = true;
            backgroundWorker1.CancelAsync();
            button1.Enabled = false;
            Close();
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            progressBar1.Value = e.ProgressPercentage;
            label1.Text += e.UserState.ToString();
        }
    }

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