关于C# Windows 程序设计里的button click事件的分析
2010-06-08 14:34
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首先在VS2010里建立一个windows程序,只带有一个button1。点击button1,出现一个messagebox展示Hello, world!程序。我相信这个程序大家都会的。
下面是源代码
Form1.Designer.cs
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For1.cs
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主要关注这几行代码
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width: 100%;
margin: 0em;
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.csharpcode .lnum { color: #606060; }
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上面的第一行代码是给button1.click事件订阅一个button1_click方法。
这里的this.button1.Click
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font-family: consolas, "Courier New", courier, monospace;
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.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
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button1是一个windows.Form.Button类的一个实例
Click是button1类里面的一个事件,可以想象成是这样的:
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
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.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
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.csharpcode .lnum { color: #606060; }
因为你从上面的code可以看出Click是EventHanlder委托的一个变量。(虽然Button类里面对于click不见得就是这样定义的,但是你可以暂且当成这样定义)
EventHandler这个自然就是一个定义在系统层的委托:
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
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.csharpcode .asp { background-color: #ffff00; }
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.csharpcode .lnum { color: #606060; }
这个委托有2个参数,从参数的名字你也可以看出来参数的意思,第一个参数是事件的发送者,第二个参数是事件参数。
第一个参数好理解了,事件的发送者。如果你点击button1, 那这里的object sender就是button1了。
第二个参数看似不好理解,我们来看下定义:
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{
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color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
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.csharpcode .rem { color: #008000; }
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.csharpcode .str { color: #006080; }
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.csharpcode .asp { background-color: #ffff00; }
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.csharpcode .lnum { color: #606060; }
它其实就是个空参数,没什么意义。
订阅完后,你只要点击button1,系统就会调用EventHandler(this.button1_Click)里面的button1_Click方法。
在这里就是运行
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
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.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
当我们运行程序进行Debug的时候,可以对于这段代码有更好的认识
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
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.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
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.csharpcode .lnum { color: #606060; }
当点击button1的时候,你可以看到
sender = button1
e = {X= 69 Y = 28 Button = Left}
这就是说传递给button1_Click的2个参数就是
sender = button1
e = {X= 69 Y = 28 Button = Left}
其实这个不难理解。因为这个方法如果没有这2个参数,它怎么能work?
如果没有sender 它怎么知道这是哪个button1 哪个object发送的方法。比如你有2个button, button1, button2。点击的时候是不同的事件,如果没有这个参数其不是button1的事件会调到button2的,button2的会调用到button1的。
第二个参数应该是在点击的时候进行实例化的。告诉你点击的位置和方式。坐标不用说了,左键的方法更是个重要参数,不然用户邮件点击是不是也会触发这个事件呢?
到这里对里有了一定的了解了,原来click事件是这样的:
订阅这个事件: this.button1.Click += new EventHandler(this.button1_Click);
事件代表的方法:
private void button1_Click(object sender, EventArgs e)
{
// DO SOMETHING;
}
有同学就会问了,我点击这个button1,系统是怎么知道调用这个click事件的?这个就是系统的事情了,不用我们操这份心。以后有机会再做深入的研究
下面是源代码
Form1.Designer.cs
namespace EventStudy { partial class Form1 { /// <summary> /// Required designer variable. /// </summary> private System.ComponentModel.IContainer components = null; /// <summary> /// Clean up any resources being used. /// </summary> /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param> protected override void Dispose(bool disposing) { if (disposing && (components != null)) { components.Dispose(); } base.Dispose(disposing); } #region Windows Form Designer generated code /// <summary> /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// </summary> private void InitializeComponent() { this.button1 = new System.Windows.Forms.Button(); this.SuspendLayout(); // // button1 // this.button1.Location = new System.Drawing.Point(90, 159); this.button1.Name = "button1"; this.button1.Size = new System.Drawing.Size(100, 39); this.button1.TabIndex = 0; this.button1.Text = "button1"; this.button1.UseVisualStyleBackColor = true; this.button1.Click += new System.EventHandler(this.button1_Click); // // Form1 // this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F); this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; this.ClientSize = new System.Drawing.Size(284, 262); this.Controls.Add(this.button1); this.Name = "Form1"; this.Text = "Form1"; this.ResumeLayout(false); } #endregion private System.Windows.Forms.Button button1; } }
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For1.cs
using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace EventStudy { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { MessageBox.Show("Hello, world!"); } } }
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.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
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.csharpcode .alt
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.csharpcode .lnum { color: #606060; }
主要关注这几行代码
this.button1.Click += new System.EventHandler(this.button1_Click);
private void button1_Click(object sender, EventArgs e) { MessageBox.Show("Hello, world!"); }
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
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.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
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.csharpcode .lnum { color: #606060; }
上面的第一行代码是给button1.click事件订阅一个button1_click方法。
这里的this.button1.Click
private System.Windows.Forms.Button button1;
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
button1是一个windows.Form.Button类的一个实例
Click是button1类里面的一个事件,可以想象成是这样的:
public class Button { .... public event EventHandler Click; ... }
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
因为你从上面的code可以看出Click是EventHanlder委托的一个变量。(虽然Button类里面对于click不见得就是这样定义的,但是你可以暂且当成这样定义)
EventHandler这个自然就是一个定义在系统层的委托:
public delegate void EventHandler(object sender, EventArgs e);
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
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.csharpcode .lnum { color: #606060; }
这个委托有2个参数,从参数的名字你也可以看出来参数的意思,第一个参数是事件的发送者,第二个参数是事件参数。
第一个参数好理解了,事件的发送者。如果你点击button1, 那这里的object sender就是button1了。
第二个参数看似不好理解,我们来看下定义:
public class EventArgs { // Summary: // Represents an event with no event data. public static readonly EventArgs Empty; // Summary: // Initializes a new instance of the System.EventArgs class. public EventArgs(); }
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
它其实就是个空参数,没什么意义。
订阅完后,你只要点击button1,系统就会调用EventHandler(this.button1_Click)里面的button1_Click方法。
在这里就是运行
private void button1_Click(object sender, EventArgs e) { MessageBox.Show("Hello, world!"); }
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
当我们运行程序进行Debug的时候,可以对于这段代码有更好的认识
+ this {EventStudy.Form1, Text: Form1} EventStudy.Form1 + sender {Text = "button1"} object {System.Windows.Forms.Button} + e {X = 69 Y = 28 Button = Left} System.EventArgs {System.Windows.Forms.MouseEventArgs}
.csharpcode, .csharpcode pre
{
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color: black;
font-family: consolas, "Courier New", courier, monospace;
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/*white-space: pre;*/
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.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
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margin: 0em;
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.csharpcode .lnum { color: #606060; }
当点击button1的时候,你可以看到
sender = button1
e = {X= 69 Y = 28 Button = Left}
这就是说传递给button1_Click的2个参数就是
sender = button1
e = {X= 69 Y = 28 Button = Left}
其实这个不难理解。因为这个方法如果没有这2个参数,它怎么能work?
如果没有sender 它怎么知道这是哪个button1 哪个object发送的方法。比如你有2个button, button1, button2。点击的时候是不同的事件,如果没有这个参数其不是button1的事件会调到button2的,button2的会调用到button1的。
第二个参数应该是在点击的时候进行实例化的。告诉你点击的位置和方式。坐标不用说了,左键的方法更是个重要参数,不然用户邮件点击是不是也会触发这个事件呢?
到这里对里有了一定的了解了,原来click事件是这样的:
订阅这个事件: this.button1.Click += new EventHandler(this.button1_Click);
事件代表的方法:
private void button1_Click(object sender, EventArgs e)
{
// DO SOMETHING;
}
有同学就会问了,我点击这个button1,系统是怎么知道调用这个click事件的?这个就是系统的事情了,不用我们操这份心。以后有机会再做深入的研究
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