c# - WinForm 多线程。是否使用 backgroundWorker？

Question

我有一个简单的应用程序，可以触发一系列数据密集型任务。我对 WinForms 不是很有经验，我想知道在不锁定界面的情况下最好的方法。backgroundWorker 可以重复使用，还是有其他方法可以做到这一点？

谢谢

Answer 1

BackgroundWorker是一个还包括通知同步的线程。例如，如果您想在扫描完成时更新您的 UI，则常规Thread无法访问 UI 对象（只有 UI 线程可以这样做）；因此，BackgroundWorker提供了一个 Completed 事件处理程序，该处理程序在操作完成时在 UI 线程上运行。

有关更多信息，请参阅：演练：使用 BackgroundWorker 组件进行多线程 (MSDN)

和一个简单的示例代码：

var worker = new System.ComponentModel.BackgroundWorker();
worker.DoWork += (sender,e) => Thread.Sleep(60000);
worker.RunWorkerCompleted += (sender,e) => MessageBox.Show("Hello there!");
worker.RunWorkerAsync();

Answer 2

backgroundWorker 可以使用。

它的好处 - 它允许您更新进度条并与 UI 控件交互。( WorkerReportsProgress)

它还具有取消机制。( WorkerSupportsCancellation)

Answer 3

您可以使用 BackgroundWorker 来满足此类要求。下面是一个示例updates a label status based on percentage task [long running] completion。ProgressChanged此外，还有一个示例业务类，它设置了一些值，并通过处理程序将值设置回 UI 。DoWork是您编写长时间运行的任务逻辑的地方。在 Winforms 应用程序上添加标签和 backgroundworker 组件后复制粘贴下面的代码并试一试。您可以调试各种处理程序[RunWorkerCompleted, ProgressChanged, DoWork]并查看InitWorker方法。也请注意cancellation feature。

using System.ComponentModel;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form3 : Form
    {
        private BackgroundWorker _worker;
        BusinessClass _biz = new BusinessClass();
        public Form3()
        {
            InitializeComponent();
            InitWorker();
        }

        private void InitWorker()
        {
            if (_worker != null)
            {
                _worker.Dispose();
            }

            _worker = new BackgroundWorker
            {
                WorkerReportsProgress = true,
                WorkerSupportsCancellation = true
            };
            _worker.DoWork += DoWork;
            _worker.RunWorkerCompleted += RunWorkerCompleted;
            _worker.ProgressChanged += ProgressChanged;
            _worker.RunWorkerAsync();
        }


        void DoWork(object sender, DoWorkEventArgs e)
        {
            int highestPercentageReached = 0;
            if (_worker.CancellationPending)
            {
                e.Cancel = true;
            }
            else
            {
                double i = 0.0d;
                int junk = 0;
                for (i = 0; i <= 199990000; i++)
                {
                    int result = _biz.MyFunction(junk);
                    junk++;

                    // Report progress as a percentage of the total task.
                    var percentComplete = (int)(i / 199990000 * 100);
                    if (percentComplete > highestPercentageReached)
                    {
                        highestPercentageReached = percentComplete;
                        // note I can pass the business class result also and display the same in the LABEL  
                        _worker.ReportProgress(percentComplete, result);
                        _worker.CancelAsync();
                    }
                }

            }
        }

        void RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Cancelled)
            {
                // Display some message to the user that task has been
                // cancelled
            }
            else if (e.Error != null)
            {
                // Do something with the error
            }
        }

        void ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            label1.Text =  string.Format("Result {0}: Percent {1}",e.UserState, e.ProgressPercentage);
        }
    }

    public class BusinessClass
    {
        public int MyFunction(int input)
        {
            return input+10;
        }
    }
}

Answer 4

后台工作人员将是一个不错的选择

有关更多信息，请查看此处 http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx