后台工作程序持续运行问题 C#

Question

我使用后台工作程序创建了一个C#项目。它包含一个“开始”按钮，用于启动后台工作程序。这是我的代码：

using System.Threading.Tasks;
using System.Windows;

namespace Test
{

    public partial class MainWindow : Window
    {

        int status = 0;

        private void btnstart_Click(object sender, RoutedEventArgs e)
        {

            worker.DoWork += worker_DoWork;
            worker.RunWorkerCompleted += worker_RunWorkerCompleted;
            worker.RunWorkerAsync();
            Console.WriteLine("Background worker started successfully");
            btnsave.IsEnabled = false;
        }

        private void worker_DoWork(object sender, DoWorkEventArgs e)
        {

                if (worker.CancellationPending)
                {
                    e.Cancel = true;
                    return;
                }
               Console.WriteLine("Status : " + status);
                if (status == 0)
                {
                    status = 1;
                }
        }

        private void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
          Console.WriteLine("worker completed");
          btnsave.IsEnabled = true;
        }
    }
}

但是每次我点击开始按钮时，都会得到以下输出结果。

attempt 1.

Status : 0
The thread 0x23dc has exited with code 0 (0x0).
Status : 1


attempt 2.

Status : 0
The thread 0x148 has exited with code 0 (0x0).
Status : 1
Status : 1

attempt 3.

Status : 0
The thread 0x128 has exited with code 0 (0x0).
Status : 1
Status : 1
Status : 1

我在现有的工作者完成后才启动后台工作者。那么为什么“状态”日志会打印出来呢？

- Abdul Manaf

---

您正在多次注册事件处理程序，而没有进行注销。因此，将会多次调用“做工作”事件处理程序。 - kennyzx

Answer 1

问题源于事件处理程序的赋值：

worker.RunWorkerCompleted += worker_RunWorkerCompleted;

每次点击按钮时都会执行此操作。由于是“+=”，您会多次赋值。

只需在窗口初始化中添加事件处理程序即可：

using System.Threading.Tasks;
using System.Windows;

namespace Test
{

    public partial class MainWindow : Window
    {

        int status = 0;

        // should be called when the window is loaded
        private void ApplicationStart()
        {
            worker.DoWork += worker_DoWork;
            worker.RunWorkerCompleted += worker_RunWorkerCompleted;
        }

        private void btnstart_Click(object sender, RoutedEventArgs e)
        {            
            worker.RunWorkerAsync();
            Console.WriteLine("Background worker started successfully");
            btnsave.IsEnabled = false;
        }

        private void worker_DoWork(object sender, DoWorkEventArgs e)
        {

                if (worker.CancellationPending)
                {
                    e.Cancel = true;
                    return;
                }
               Console.WriteLine("Status : " + status);
                if (status == 0)
                {
                    status = 1;
                }
        }

        private void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
          Console.WriteLine("worker completed");
          btnsave.IsEnabled = true;
        }
    }
}

- Romano Zumbé

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谢谢Romano Zumbe，它运行良好。 - Abdul Manaf