Question

我正在尝试使用Backgroundworker来保持我的主UI线程处于打开状态而不会冻结。我正在逐步执行我的代码，并在backgroundWorker1.RunWorkerAsync();上设置了一个断点，一旦点击该方法，就在foreach行 - ＆gt;从未被击中过。

使用Backgroundworker的正确方法是什么？

public Form1()
{
    InitializeComponent();
    backgroundWorker1.WorkerReportsProgress = true; 
    backgroundWorker1.WorkerSupportsCancellation = true;
}
private void btnQuery_Click(object sender, EventArgs e)
{
    grid1.Rows.Clear();
    backgroundWorker1.RunWorkerAsync();
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    foreach (string name in studentRoster)
    {
        InsertIntoDB();
    }
}

Answer 1

以下是添加了处理程序的代码和一些注释。

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        backgroundWorker1.WorkerReportsProgress = true;
        backgroundWorker1.WorkerSupportsCancellation = true;
        backgroundWorker1.DoWork += new DoWorkEventHandler(BackgroundWorker_DoWork);
        backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(BackgroundWorker_ProgressChanged);
        backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(BackgroundWorker_RunWorkerCompleted);

    }
    private void btnQuery_Click(object sender, EventArgs e)
    {
        grid1.Rows.Clear();
        backgroundWorker1.RunWorkerAsync();
    }
    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        foreach (string name in studentRoster)
        {
            InsertIntoDB();

            // You can report progress by calling the following function.
            //backgroundWorker1.ReportProgress(int percentProgress, object userState)
            // You can set the percentProgress to any valid integer value,
            // and userState can be any object you want.

            // You can also check to see if this operation has been sent a request to cancel.
            if (backgroundWorker1.CancellationPending)
            {
                e.Cancel = true;
                return;
            }
        }

        // You can send information back to the main thread by setting e.Result to any object you want.
    }
    private void BackgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        // Do something with the event that is being raised.
        // To pass a value back through to this event, use the percentProgress and userState
        // parameters of the ReportProgress function.
        // the userState object that you pass will be received here as e.UserState
    }
    private void BackgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        // This event is raised by the background worker when the DoWork method is completed.
        // You can receive information back from the worker thread by evaluating e.Result
    }
}

}

BackgroundWorker事件永远不会执行

1 个答案: