• 异步调用backgroudworker


    先看一个小例子:C#客户端打开一个控件,控件中加载了好多数据大约要用5秒中,如果我们直接打开控件,那么这个控件就要5秒中才能弹出来,当然这个时候用户已经把他Kill了。这个时候我们就需要先给用户把控件UI加载出来,给出来一个假象,然后数据在后台加载就OK了。具体看一下怎么做。

     
     1         public Form1()
     2         {
     3             InitializeComponent();
     4 
     5             //如果要设置进度条和取消事件,则必须先设定他们的属性可以执行
     6             backgroundWorker1.WorkerReportsProgress=true;
     7             backgroundWorker1.WorkerSupportsCancellation=true;
     8 
     9             //注册要执行的耗时事件
    10             backgroundWorker1.DoWork += backgroundWorker1_DoWork;
    11             //注册进度条事件
    12             backgroundWorker1.ProgressChanged += backgroundWorker1_ProgressChanged;
    13             //注册执行完backgroundworker事件
    14             backgroundWorker1.RunWorkerCompleted += backgroundWorker1_RunWorkerCompleted;
    16         } 
    17 
    18         /// <summary>
    19         /// 点击开始
    20         /// </summary>
    21         /// <param name="sender"></param>
    22         /// <param name="e"></param>
    23         private void startAsyncButton_Click(object sender, EventArgs e)
    24         {
    25             //这里做判断就是判断backgroundWorker是否在执行,如果没有在执行就开始工作,执行Dowork中的事件
    26             if (!backgroundWorker1.IsBusy)
    27             {
    28                 backgroundWorker1.RunWorkerAsync();
    29             }
    30         }
    31 
    32         /// <summary>
    33         /// 开始执行耗时事件
    34         /// </summary>
    35         /// <param name="sender"></param>
    36         /// <param name="e"></param>
    37         private void backgroundWorker1_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
    38         {
    39             BackgroundWorker worker = sender as BackgroundWorker;
    40             for (int i = 1; i <= 10; i++)
    41             {
    42                 if (worker.CancellationPending)
    43                 {
    44                     e.Cancel = true;
    45                     break;
    46                 }
    47                 else
    48                 {
    49                     Thread.Sleep(500);
    50                     //更改进度条值,触发进度条事件,这里不能实现UI代码,要在进度条改变事件里实现
    51                     worker.ReportProgress(i * 10);
    52                 }
    53             }
    54         }
    55 
    56         /// <summary>
    57         /// 点击取消执行事件
    58         /// </summary>
    59         /// <param name="sender"></param>
    60         /// <param name="e"></param>
    61         private void cancelAsyncButton_Click(object sender, EventArgs e)
    62         {
    63             if (backgroundWorker1.WorkerSupportsCancellation == true)
    64             {
    65                 // Cancel the asynchronous operation.
    66                 backgroundWorker1.CancelAsync();
    67             }
    68         }
    69 
    70 
    71         /// <summary>
    72         /// 进度条改变事件
    73         /// </summary>
    74         /// <param name="sender"></param>
    75         /// <param name="e"></param>
    76         private void backgroundWorker1_ProgressChanged(object sender, System.ComponentModel.ProgressChangedEventArgs e)
    77         {
    78             radLabel1.Text = (e.ProgressPercentage.ToString() + "%");
    79         }
    80 
    81         /// <summary>
    82         /// backgroundWorker1执行完事件
    83         /// </summary>
    84         /// <param name="sender"></param>
    85         /// <param name="e"></param>
    86      private void backgroundWorker1_RunWorkerCompleted(object sender, System.ComponentModel.RunWorkerCompletedEventArgs e)
    87         {
    88         }
    89     }

    具体代码如下:

    运行结果:

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  • 原文地址:https://www.cnblogs.com/cn-blogs/p/3718877.html
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