Application.DoEvent()
丰富的用户体验是所有交互式应用程序的主要方面。需要用户交互的软件必须尽可能快地响应用户的活动。与此同时,应用程序必须能够处理数据以便将结果显示给用户。
在应用程序中使用多个线程可以将用户界面 (UI) 执行的任务与后台执行的任务分开。通过此方式组织任务,可以由 UI 响应用户输入,同时由后台进程进行数据处理。
创建辅助线程
应用程序可以创建一个或多个线程以执行方法。创建辅助(或从属)线程的第一个步骤是创建 ThreadStart 代理,指定要由该线程执行的方法。然后将 ThreadStart 代理传递给 Thread 类的构造函数。例如,要启动新的线程并执行 MyFunction 方法,请调用 Thread 类的 Start 方法,如下所示:
ThreadStart starter = new ThreadStart(MyFunction); Thread t = new Thread(starter); t.Start();
从辅助线程更新用户界面
您可以使用 Control.Invoke 从 UI 线程以外的其他线程更新用户界面 (UI)。此方法在 UI 线程上的控件线程上下文中执行代理。.NET Framework 精简版只支持 .NET Framework 完整版中的重载 Control.Invoke 方法。Control.Invoke 只使用一个参数:一个指定在 UI 线程上执行哪个方法的代理。该代理的类型必须为 EventHandler,并且具有以下签名:
void MyFunctionName(object sender, EventArgs e)
需要注意的一点是,如果要在辅助线程中更新 UI,就必须在代码中调用 Application.DoEvents()。调用 Application.DoEvents() 可确保辅助线程激发的任何事件都由该 UI 线程处理。
下面的示例代码说明如何创建辅助线程,然后从 UI 线程和辅助线程更新名为 listBox1 的 ListBox 控件:
1
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
32
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
33
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
34
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
35
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
36
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
37
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
38
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
39
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
40
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
41
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
42
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
43
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
44
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
45
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
46
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)