当RunWorkerAsync被调用一次时，BackgroundWorker的DoWork被调用两次？ [英] DoWork of BackgroundWorker is called twice when RunWorkerAsync is called once?

问题描述

我已经在一个可以工作的类中创建了一个backgroundworker，但是如果我调用并等到结束运行，则再次调用它，它将执行两次相同的过程

I have create a backgroundworker in an class it works, but if i call and wait until the end run, call it for the second time it will do the same process twice

我认为 bw.DoWork + =

private void button1_Click(object sender, EventArgs e)
{
    nptest.test.start("null", "null");    
}


namespace nptest
{
    class test
    {
        public static void start(string str, string strb)
        {
            if (bw.IsBusy != true)
            {
                bw.WorkerSupportsCancellation = true;
                bw.DoWork += (obj, e) => bw_DoWork(str, strb);
                bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
                bw.RunWorkerAsync();
            }
        }
        private static BackgroundWorker bw = new BackgroundWorker();
        private static void bw_DoWork(string str, string strb)
        {
            System.Windows.Forms.MessageBox.Show("initializing BackgroundWorker");
        }
        private static void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if ((e.Cancelled == true))
            {
                Console.WriteLine("Canceled");
            }
            else if (!(e.Error == null))
            {
                Console.WriteLine("Error: " + e.Error.Message);
            }
            bw.Dispose();

        }
    }
}

问题已解决

  class test
    {
        private static List<object> arguments = new List<object>();

        // initializing with program startup
        public static void bwinitializing()
        {
            bw.WorkerSupportsCancellation = true;
            bw.DoWork += new DoWorkEventHandler(bw_DoWork);
            bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
        }

        public static void start(string str, string strb)
        {
            if (bw.IsBusy != true)
            {
                arguments.Clear();
                arguments.Add(str);
                arguments.Add(strb);
                bw.RunWorkerAsync(arguments);
            }
        }
        private static BackgroundWorker bw = new BackgroundWorker();
        private static void bw_DoWork(object sender, DoWorkEventArgs e)
        {
            List<object> genericlist = e.Argument as List<object>;
            System.Windows.Forms.MessageBox.Show("BackgroundWorker " + genericlist[0]);

        }

推荐答案

我有遇到与上述评论者 Power-Mosfet相同的问题

I have encounter same problem as above commenter "Power-Mosfet"

，最后，添加了 new BackgroundWorker（）然后分配给全局bw值将解决我的问题。

and in the end, added a new BackgroundWorker() then assigned to the global bw value will fix my problem.

代码是，更改自：

private BackgroundWorker gBgwDownload;

private void yourFunction_bw(xxx)
{
    // Create a background thread
    gBgwDownload.DoWork += bgwDownload_DoWork;
    gBgwDownload.RunWorkerCompleted += bgwDownload_RunWorkerCompleted;
    //omited some code
    gBgwDownload.RunWorkerAsync(paraObj);
}

至：

private BackgroundWorker gBgwDownload;

private void yourFunction_bw(xxx)
{
    // Create a background thread
    gBgwDownload = new BackgroundWorker(); /* added this line will fix problem */
    gBgwDownload.DoWork += bgwDownload_DoWork;
    gBgwDownload.RunWorkerCompleted += bgwDownload_RunWorkerCompleted;
    //omited some code
    gBgwDownload.RunWorkerAsync(paraObj);

}

这篇关于当RunWorkerAsync被调用一次时，BackgroundWorker的DoWork被调用两次？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！