点击一个按钮n次，输出n次.Required仅为一次单击产生的一个输出

好的。。所以我不知道为什么会发生这种事。我想我在Java中也看到过类似的问题。。但我一点也不懂。我使用的是C#，其中我有一个listview，单击按钮即可使用远程服务器更新状态。我已经得到了为此工作的代码。但是当我再次点击同一个按钮时，输出会显示两次。如果我再点击一次，输出会显示三次，以此类推！！例如：第一次点击：

xxx     login to server failed
yyy     login to server failed

第二次点击：

xxx     login to server failed
xxx     login to server failed
yyy     login to server failed
yyy     login to server failed

我使用了一个backgroundworker和一个并行的foreach循环。我在这里输入了所有涉及的函数，这样就有了所有的信息。。抱歉，如果太多了！这是我的代码：

    private void button1_Click(object sender, EventArgs e)                        //get update button
    {
        GlobalVariables._count = 0;
        Status.statusProgress obj1 = new Status.statusProgress();
        if (getupdate_button.Text == "Stop")
        {
            backgroundWorker1.CancelAsync();
            getupdate_button.Enabled = false;
        }
        else
        {
            getupdate_button.Text = "Stop";
            listView1.Items.Clear();
            //do stuff
            backgroundWorker1.ProgressChanged += backgroundWorker1_ProgressChanged;
        }
        if (backgroundWorker1.IsBusy)
        {
            if (backgroundWorker1.CancellationPending != true)
            {
                MessageBox.Show("Please wait till the pervious operation is completed!");
            }
            else 
            {
                Complete_label.Text = "Cancelling...";
                Complete_label.Visible = true;
            }
        }
        else
        {
            backgroundWorker1.RunWorkerAsync(obj1);                                //calling background worker
        }
    }

做工作：

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)                         //the boss-- the background worker
    {
        System.ComponentModel.BackgroundWorker worker;
        worker = (System.ComponentModel.BackgroundWorker)sender;
        Status obj1 = new Status();
        Status.statusProgress obj = new Status.statusProgress();
        if ((backgroundWorker1.CancellationPending == true))
        {
            e.Cancel = true;
        }
        else
        {
            obj1.Calculation(worker, e);
        }
        e.Result = obj;
    }

计算方法：

    public void Calculation(System.ComponentModel.BackgroundWorker worker, System.ComponentModel.DoWorkEventArgs e)
    {
        Status.statusProgress obj = (Status.statusProgress)e.Argument;
        //stuff
            var file = File.ReadAllLines(obj.SourceFile);
            List<string> namelist = null;
            namelist = new List<string>(file);
            Parallel.ForEach(namelist, /*new ParallelOptions { MaxDegreeOfParallelism = 4 }, */line =>
            //foreach (string line in namelist)
            {
                var progress = new statusProgress();
                progress.TotalSysCount = obj.TotalSysCount;
                Status.statusProgress result = new Status.statusProgress();
                if (worker.CancellationPending)
                {
                    e.Cancel = true;
                    worker.ReportProgress(result.SysCount, result);
                }
                else
                {
                    //this.SystemName = line;//file.ReadLine();                        
                    progress.SystemName = line;
                    //result = progress;
                    result = OneSystem(line);
                    //work with result
        }
                count1 = Interlocked.Increment(ref count);
                //stuff
                worker.ReportProgress(count1, progress);
                Thread.Sleep(200);
             });
        }
    }

报告进度方法：

     private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
    try
                {
                    var newItem = listView1.Items.Add("");
                    newItem.SubItems.Add(result.SystemName);
                    newItem.SubItems.Add(result.StatusString);
                    newItem.SubItems.Add(result.AvailableUpdatesCount.ToString());
                }
                catch (Exception ex)
                {}
            update_text(result);
            progressBar1.Maximum = 100;
            int perc = (int)((result.SysCount * 100) / result.TotalSysCount);
            progressBar1.Value = perc;
            Complete_label.Text = perc.ToString()+"%";
            if (progressBar1.Value == 100)
            {
                Complete_label.Text = "Complete!";
                getupdate_button.Enabled = false;
            }
    }

backgroundWorker1.ProgressChanged += backgroundWorker1_ProgressChanged;