使用backgroundworker时出错

Question

//This is my code

private void btnGenSumm_Click(object sender, EventArgs e)
{
    if (backgroundWorker1.IsBusy != true)
    {
        btnGenSumm.Enabled = false;
        btnExpSum.Enabled = false;
        btnClose.Enabled = false;
        pBox1.Visible = true;
        backgroundWorker1.RunWorkerAsync();
    }
}

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
        BackgroundWorker worker = sender as BackgroundWorker;
        loadSummSales(); // this is the process
        System.Threading.Thread.Sleep(50);
}

private void backgroundWorker1_RunWorkerCompleted(object sender, 
    RunWorkerCompletedEventArgs e)
{
        pBox1.Visible = false;
}

There is no error on execution of the process on the first click, but when i try to click the command button (btnGenSumm) again to repeat the processs, I got error "value dispose cannot be called while doing createhandle"., Please help me with this.

Answer 1

I would always create a new worker before starting a task; this avoids those issues.

private void btnGenSumm_Click(object sender, EventArgs e)
{
    // WorkerFactory creates your worker and hooks up the DoWork 
    // and RunWorkerCompleted events
    var backgroundWorker1 = WorkerFactory();

    // ...
    // Disable access to this Click event in the UI here

    backgroundWorker1.RunWorkerAsync();
}

private void backgroundWorker1_RunWorkerCompleted(
    object sender, 
    RunWorkerCompletedEventArgs e)
{
    // Re-enable access to the Click event in the UI here
}

Using this approach there is no way that the worker can ever be accessed while it is running and you are guaranteed that whenever the user clicks the button the last worker has completed and there is no nasty IsBusy fudge.

UPDATE

Explicitly WorkerFactory does something like this

private BackgroundWorker WorkerFactory()
{
    var worker = new BackgroundWorker();
    worker.DoWork += backgroundWorker1_DoWork;
    worker.RunWorkerCompleted += backgroundWorker1_RunWorkerCompleted;

    return worker;
}