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。

 

　       public Form1()
        {
            InitializeComponent();

            //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
            backgroundWorker1.WorkerReportsProgress=true;
            backgroundWorker1.WorkerSupportsCancellation=true;

            //注册要执行的耗时事件
            backgroundWorker1.DoWork += backgroundWorker1_DoWork;
            //注册进度条事件
            backgroundWorker1.ProgressChanged += backgroundWorker1_ProgressChanged;
            //注册执行完backgroundworker事件
            backgroundWorker1.RunWorkerCompleted += backgroundWorker1_RunWorkerCompleted;
        } 

        /// <summary>
        /// 点击开始
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void startAsyncButton_Click(object sender, EventArgs e)
        {
            //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
            if (!backgroundWorker1.IsBusy)
            {
                backgroundWorker1.RunWorkerAsync();
            }
        }

        /// <summary>
        /// 开始执行耗时事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void backgroundWorker1_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
        {
            BackgroundWorker worker = sender as BackgroundWorker;
            for (int i = 1; i <= 10; i++)
            {
                if (worker.CancellationPending)
                {
                    e.Cancel = true;
                    break;
                }
                else
                {
                    Thread.Sleep(500);
                    //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
                    worker.ReportProgress(i * 10);
                }
            }
        }

        /// <summary>
        /// 点击取消执行事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void cancelAsyncButton_Click(object sender, EventArgs e)
        {
            if (backgroundWorker1.WorkerSupportsCancellation == true)
            {
                // Cancel the asynchronous operation.
                backgroundWorker1.CancelAsync();
            }
        }


        /// <summary>
        /// 进度条改变事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void backgroundWorker1_ProgressChanged(object sender, System.ComponentModel.ProgressChangedEventArgs e)
        {
            radLabel1.Text = (e.ProgressPercentage.ToString() + "%");
        }

        /// <summary>
        /// backgroundWorker1执行完事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
　　　　　private void backgroundWorker1_RunWorkerCompleted(object sender, System.ComponentModel.RunWorkerCompletedEventArgs e)
        {
        }
    }

具体代码如下：

运行结果：