VS2005 new control for windows programming ：BackgroundWorker

VS2005新增控件介绍：BackgroundWorker

BackgroundWorker组件：

1、使用BackgroundWorker组件时，您可以在不同于应用程序的主用户界面线程的另一线程上异步（“在后台”）执行耗时的 操作。

2、若要使用BackgroundWorker，只需要告诉该组件要在后台执行的耗时的辅助方法，然后调用RunWorkerAsync方法。

3、在辅助方法以异步方式运行的同时，您的调用线程继续正常运行。该方法运行完毕，BackgroundWorker激发RunWorkerCompleted事件（看选择包含操作结果）向调用线程发出警报。

BackgroundWorker示例：后台下载文件


using System;


using System.Collections.Generic;


using System.ComponentModel;


using System.Drawing;


using System.Threading;


using System.Windows.Forms;


using System.Xml;




namespace UseBackgroundWorker




...{


public partial class Form1 : Form




...{


private XmlDocument document = null;


public Form1()




...{


InitializeComponent();


}




private void dowloadButton_Click(object sender, EventArgs e)




...{


this.backgroundWorker1.RunWorkerAsync();




// Disable the button for the duration of the download.


this.dowloadButton.Enabled = false;




// Wait for the BackgroundWorker to finish the download.


while (this.backgroundWorker1.IsBusy)




...{


// Keep UI messages moving, so the form remains


// responsive during the asynchronous operation.


Application.DoEvents();


}




// The download is done, so enable the button.


this.dowloadButton.Enabled = true;




}




private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)




...{


document = new XmlDocument();




// Replace this file name with a valid file name.


document.Load(@"http://www.tailspintoys.com/sample.xml");




// Uncomment the following line to


// simulate a noticeable latency.


//Thread.Sleep(5000);




}




private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)




...{


if (e.Error == null)




...{


MessageBox.Show(document.InnerXml, "Download Complete");


}


else




...{


MessageBox.Show(


"Failed to download file",


"Download failed",


MessageBoxButtons.OK,


MessageBoxIcon.Error);


}




}


}


}