创建新的 BackgroundWorker 实例

BackgroundWorker 通常用于执行任务，有时耗时，而不会阻止 UI 线程。

// BackgroundWorker is part of the ComponentModel namespace.
using System.ComponentModel;

namespace BGWorkerExample 
{
     public partial class ExampleForm : Form 
     {

      // the following creates an instance of the BackgroundWorker named "bgWorker"
      BackgroundWorker bgWorker = new BackgroundWorker();

      public ExampleForm() { ...