dotnet中一个重要组件-BackgroundWorker
最近一直在看wse3.0,从一个例子中偶然的收获。虽然通过后台操作,从而减少用户交互时的“僵硬”体验一直是每个程序员的追求,在今天这样ajax的时代里面更加显的重要。一切为了用户,一切为了更丰富愉快的体验。本文并不是ajax相关的东东。伟大的BackgroundWorker!
BackgroundWorker 类允许您在单独的专用线程上运行操作。耗时的操作(如下载和数据库事务)在长时间运行时可能会导致用户界面 (UI) 似乎处于停止响应状态。如果您需要能进行响应的用户界面,而且面临与这类操作相关的长时间延迟,则可以使用 BackgroundWorker 类方便地解决问题。
您必须非常小心,确保在 DoWork 事件处理程序中不操作任何用户界面对象。而应该通过 ProgressChanged 和 RunWorkerCompleted 事件与用户界面进行通信 |
1。给组件注册事件处理方法:
//正式做事情的地方
backgroundWorker1.DoWork +=
new DoWorkEventHandler(backgroundWorker1_DoWork);
//任务完称时要做的,比如提示等等
backgroundWorker1.RunWorkerCompleted +=
new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
//任务进行时,报告进度
backgroundWorker1.ProgressChanged +=
new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
2。添加具体事件处理方法
DoWork | 调用 RunWorkerAsync 时发生。 | |
ProgressChanged | 调用 ReportProgress 时发生。 | |
RunWorkerCompleted | 当后台操作已完成、被取消或引发异常时发生。 |
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//这个例子没有做什么事情,完全是看看效果而已,但同时有个大问题,我也不知道为什么,没有去除僵硬情况。
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namespace BackgroundWorkerTest
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{
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public partial class Form1 : Form
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{
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public Form1()
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{
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InitializeComponent();
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InitialzeBackgroundWorker();
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}
11![](/Images/OutliningIndicators/InBlock.gif)
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private void InitialzeBackgroundWorker()
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{
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this.backgroundWorker1.DoWork+=new DoWorkEventHandler(backgroundWorker1_DoWork);
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this.backgroundWorker1.ProgressChanged+=new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
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this.backgroundWorker1.RunWorkerCompleted+=new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
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}
18![](/Images/OutliningIndicators/InBlock.gif)
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private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
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{
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MessageBox.Show("Completly");
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}
24![](/Images/OutliningIndicators/InBlock.gif)
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private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
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{
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this.progressBar1.Value = e.ProgressPercentage;
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}
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private void backgroundWorker1_DoWork(object sender,DoWorkEventArgs e)
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{
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e.Result = ComputeFibonacci(this.backgroundWorker1, e);
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}
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private int ComputeFibonacci(object sender, DoWorkEventArgs e)
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{
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for (int i = 0; i < 100000; i++)
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{
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if (this.backgroundWorker1.CancellationPending)
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{
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e.Cancel = true;
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}
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else
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{
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this.backgroundWorker1.ReportProgress(i);
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}
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}
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return 0;
51![](/Images/OutliningIndicators/InBlock.gif)
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}
53![](/Images/OutliningIndicators/InBlock.gif)
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private void button1_Click(object sender, EventArgs e)
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{
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this.backgroundWorker1.RunWorkerAsync();
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}
59![](/Images/OutliningIndicators/InBlock.gif)
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private void button2_Click(object sender, EventArgs e)
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{
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this.backgroundWorker1.CancelAsync();
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}
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}
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}
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给出另一种使用:继承BackgroundWorker:
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BackgroundWorker在长时间的webservices中特别有用。
posted on 2006-07-05 10:25 flyingchen 阅读(2960) 评论(1) 编辑 收藏 举报