后台工作者连续运行 issue c#

Question

我已经使用后台工作者创建了一个 c# 项目。它包含一个用于启动后台工作程序的 "Start" 按钮。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，我都会得到这样的输出

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

我只在现有工作人员完成后才启动后台工作人员。那为什么"status"日志会这样打印呢

Answer 1

事件处理程序分配导致问题：

worker.RunWorkerCompleted += worker_RunWorkerCompleted;

每次单击按钮时都会执行此操作。因为它是 a += 你多次分配它。

只需在window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;
        }
    }
}

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