WinForm BackgroundWorker实现异步执行代码

int sum=0;
private void Form1_Load(object sender, EventArgs e)
{
BackgroundWorker backWork = new BackgroundWorker();
backWork.DoWork += new DoWorkEventHandler(backWork_DoWork);
backWork.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backWork_RunWorkerCompleted);
backWork.RunWorkerAsync();
}

void backWork_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
MessageBox.Show(sum.ToString());
}

void backWork_DoWork(object sender, DoWorkEventArgs e)
{
for (long i = 0; i < 1000000000; i++)
{
sum += i;
}
}