Winfrom 线程安全

在winfrom开发过程中有时候会遇到在子线程中操作UI线程的操作，这个时候如果在子线程中直接操作控件的话会有下面的错误发生。如下图所示：

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

        private void button1_Click(object sender, EventArgs e)
        {
            Thread myThread = new Thread(new ThreadStart(SetText));
            myThread.Start();
        }

        private void SetText()
        {
            textBox1.Text = "this is MyText!";
        }
    }

这段代码运行之后会直接报错：

那也就是说在winfrom中我们是不能直接操作UI线程的。那该怎么操作呢？

在微软官方文档中推荐使用两种方式：

1、使用委托

 public partial class delegateFrom : Form
    {
        private delegate void SafeCallMoteod();

        public delegateFrom()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (textBox1.InvokeRequired)
            {
                var d = new SafeCallMoteod(SetText);
                textBox1.Invoke(d, null);
            }
            else
            {
                SetText();               
            }
            Thread myThread = new Thread(new ThreadStart(SetText));
            myThread.Start();
        }

        private void SetText()
        {
            textBox1.Text = "this is MyText!";
        }

        /// 

        /// 应用程序的主入口点。
        /// 
        [STAThread]
        private static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new delegateFrom());
        }

该段代码可以正常显示：

2、另外一种可以采用BackgroundWorker来操作，示例如下：

注：使用BackgroundWorker可以直接从工具箱中拖一个。

 

BackGroundWork有这三个事件，我们可以通过监听这三个事件来达到我们的目的：

详细代码如下：

 public partial class frmBackgroundWorker : Form
    {
        public frmBackgroundWorker()
        {
            InitializeComponent();
            this.backgroundWorker1.WorkerReportsProgress = true;
            this.backgroundWorker1.WorkerSupportsCancellation = true;
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            btnStart.Enabled = false;
            backgroundWorker1.RunWorkerAsync();
            btnCancle.Enabled = true;
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            for (int i = 0; i <= 20; i++)
            {
                if ((sender as BackgroundWorker).CancellationPending)
                {
                    e.Cancel = true;
                    break;
                }
                else
                {
                    Thread.Sleep(1000);
                    (sender as BackgroundWorker).ReportProgress(i * 5);
                    e.Result = txtValue.Text + i.ToString();
                }
            }
        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Error != null)
            {
                MessageBox.Show(e.Error.Message);
            }
            else if (e.Cancelled)
            {
                txtValue.Text = "Canceled";
            }
            else
            {
                // Finally, handle the case where the operation
                // succeeded.
                txtValue.Text = e.Result.ToString();
            }
        }

        private void btnCancle_Click(object sender, EventArgs e)
        {
            btnCancle.Enabled = false;
            backgroundWorker1.CancelAsync();
            btnStart.Enabled = true;
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            //获取异步任务执行的百分比
            progressBar1.Value = e.ProgressPercentage;
        }

        /// 

        /// 应用程序的主入口点。
        /// 
        [STAThread]
        private static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new frmBackgroundWorker());
        }
    }
}

个人感觉BackGroundWork这种事件回调的处理方式更优雅一些。