Question

场景_1。
1.用户。按下“开始”按钮；
2.程序。在“ flowLayoutPanel1”中创建用户元素“ ucBackgroundWorker”的实例；
3.程序。在“ treeView1”中创建一个节点；

“ Scenario_1”可以无限次重复。

场景_2。
有： -在“ flowLayoutPanel1”中启动了多个过程；
-在“ treeView1”中有一棵进程树；

场景：
1.用户。将光标移动到“ treeView1”；
2.程序。在“ flowLayoutPanel2”中，显示流程（实例
光标所在节点的“ ucBackgroundWorker”“）；

据我了解，我尝试实施此方案（方案_1 +方案_2）。我以为可以为用户元素实例分配索引，然后根据索引显示在“ flowLayoutPanel2”中。
为了进行测试，该脚本的按钮创建了一个按钮“ btShowTheProces”
但是该项目不起作用。
调试时出现错误。
Form3.cs

flowLayoutPanel1.Controls.Add (ucBgWorker [i_ucBWrk]);

错误“对象引用未指向该对象的实例。”
ucBgWorker = null;

您的问题
1.如何解决错误？
2.我可以正确解决我的问题吗？
3.完成此方案的其他方法有哪些？
例如，该过程不是绑定到索引，而是绑定到“字符串”吗？
例如，类似这样的

string i_ucBWrk;
i_ucBWrk = "process_1";
flowLayoutPanel1.Controls.Add (ucBgWorker [i_ucBWrk]);

Form3.cs

命名空间rsh { 公共局部类Form3：表单 { // ucBackgroundWorker [] ucBgWorker = null;

    int i_ucBWrk=0;
    private ucBackgroundWorker[] ucBgWorker;

    int procNumb;

    public Form3()
    {
        InitializeComponent();
    }

    // после выбора узла дерева
    void treeView1_AfterSelect(object sender, TreeViewCancelEventArgs e)
    {

    }

    private void btnStart_Click(object sender, EventArgs e)
    {
        i_ucBWrk++;

        ucBgWorker[i_ucBWrk] = new ucBackgroundWorker();

        // ucBgWorker[i_ucBWrk].Done += new Action<string, EventArgs>(Worker_Done);
        // ucBgWorker[i_ucBWrk].Cancel += new Action<string, EventArgs>(Worker_Cancel);

        flowLayoutPanel1.Controls.Add(ucBgWorker[i_ucBWrk]);

        ucBgWorker[i_ucBWrk].Run(1);            
        // ucBgWorker.Run(Convert.ToInt32(textBox1.Text));
    }

    void Worker_Done(string arg, EventArgs evtarg)
    {
        label1.Text = arg + " Done One";
        //System.Threading.Thread.Sleep(1000);
    }

    void Worker_Cancel(string arg, EventArgs evtarg)
    {
        label1.Text = arg + " Cancel Click";
        //System.Threading.Thread.Sleep(1000);
    }


    //  show the process
    private void btShowTheProces_Click(object sender, EventArgs e)
    {
        procNumb = Convert.ToInt32(numericUpDown1.Value);

        flowLayoutPanel2.Controls.Clear();
        flowLayoutPanel2.Controls.Add(ucBgWorker[procNumb]);
    }
}

}

ucBackgroundWorker.cs

namespace rsh
{
    public partial class ucBackgroundWorker : UserControl
    {
        BackgroundWorker bgWorker = null;
        public event Action<string, EventArgs> Done;
        public event Action<string, EventArgs> Cancel;

        private static bool m_continue = true;

        // Уведомляет один или более ожидающих потоков о том, что произошло событие. Этот класс не наследуется.
        // https://msdn.microsoft.com/ru-ru/library/system.threading.manualresetevent(v=vs.110).aspx
        private ManualResetEvent _resetEvent = new ManualResetEvent(false);
        //Semaphore sWaiter = new Semaphore(0, 1);


        public ucBackgroundWorker()
        {
            InitializeComponent();

            bgWorker = new BackgroundWorker();

            bgWorker.WorkerSupportsCancellation = true;
            bgWorker.WorkerReportsProgress = true;

            bgWorker.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
            bgWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
            bgWorker.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
        }

        public void Run(int counter)
        {
            if (!bgWorker.IsBusy)
            {
                bgWorker.RunWorkerAsync(counter);
            }
            _resetEvent.Set();
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            int input = int.Parse(e.Argument.ToString());

            this.BeginInvoke((MethodInvoker)delegate
            {
                lblStatus.Text = "Running";
            });

            for (int i = 1; i <= input; i++)
            {
                _resetEvent.WaitOne();
                Thread.Sleep(1000);
                (sender as BackgroundWorker).ReportProgress(i*1); // шаг
                // (sender as BackgroundWorker).ReportProgress(i * 10);
                if ((sender as BackgroundWorker).CancellationPending)
                {
                    this.BeginInvoke((MethodInvoker)delegate
                    {
                        lblStatus.Text = "Cancel";
                    });

                    e.Cancel = true;
                    return;
                }
            }
            Thread.Sleep(1000);
        }


        // This event handler deals with the results of the 
        // background operation.
        // Этот обработчик событий имеет дело с результатами
        // фоновая операция.
        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            // First, handle the case where an exception was thrown. 
            // Сначала обрабатываем случай, когда было создано исключение.
            if (e.Error != null)
            {
                MessageBox.Show(e.Error.Message);
            }
            else if (e.Cancelled)
            {
                if (Cancel != null)
                    Cancel(this.Name, EventArgs.Empty);
            }
            else
            {
                this.BeginInvoke((MethodInvoker)delegate
                {
                    lblStatus.Text = "Done";
                });

                if (Done != null)
                    Done(this.Name, EventArgs.Empty);
            }
            _resetEvent.Reset();
        }

        // This event handler updates the progress bar. 
        // Этот обработчик событий обновляет индикатор выполнения.
        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            pBar.Refresh();
            pBar.Value = e.ProgressPercentage;
        }



        // *** *** *** ***
        // *** КНОПКИ  ***
        // *** *** *** ***

        // Cancel
        private void btnCancel_Click(object sender, EventArgs e)
        {
            if (bgWorker.IsBusy)
            {
                bgWorker.CancelAsync();
            }
        }

        // Pause
        private void btnPause_Click(object sender, EventArgs e)
        {
            if (bgWorker.IsBusy)
            {
                if (btnPause.Text.ToUpper() == "PAUSE")
                {
                    btnPause.Text = "Resume";
                    m_continue = false;
                    _resetEvent.Reset();
                }
                else 
                if (btnPause.Text.ToUpper() == "RESUME")
                {

                    btnPause.Text = "Pause";
                    m_continue = true;
                    _resetEvent.Set();

                }
            }
        }


    }
}

项目-link

Answer 1

您永远不会初始化ucBgWorker数组。

将代码更改为此

private ucBackgroundWorker[] ucBgWorker = new ucBackgroundWorker[10];

与此有关的问题是，然后将您的数组设置为最大10。

最好使用列表：

private List<ucBackgroundWorker> ucBgWorker = new List<ucBackgroundWorker>();

添加以下项目：

ucBgWorker.Add(new ucBackgroundWorker());

您仍然可以按索引访问项目：

ucBackgroundWorker item = ucBgWorker[0];

只要列表中有项目。

BackgroundWorker。如何通过TreeView导航显示当前进程？

1 个答案: