特性一：委托
委托是C#语言中特有的概念，相当于C/C++中的函数指针，与C/C++中函数指针的不同之处是：委托是面向对象的、类型安全的和保险的，是引用类型。因此，对委托的使用要
“先定义、后声明，接着实例化、然后作为参数传递给方法，最后才能使用”。
1、定义委托使用关键字delegate:
delegate void SomeDelegate(type1 para1,......typen paran);
2、声明委托：
SomeDelegate d;
3、实例化委托：
d=new SomeDelegate(obj.InstanceMethod);
其中obj是对象，InstanceMethod是它的实例方法。
4、作为参数传递给方法
someMethod(d);
5、最后在此方法的实现代码中使用委托
private void someMethod(SomeDelegate someDelegate)
{
.....
//使用委托
someDelegate(arg1,arg2,....,argn);
......
}
通过委托SomeDelegate实现对方法InstanceMethod的调用，调用还必须有一个前提条件：方法InstanceMethod有参数且和定义SomeDelegate的参数一致，并且返回类型相同（本例中为void）。方法InstanceMethod的定义：
private void InstanceMethod(type1 para1,type2 para2,......,typen paran)
{
//方法体
.....
}
委托的实例化中的参数既可以是实例方法，也可以是静态方法。
使用委托实现“文字抄写员”的小程序，界面如下：
在下方文本框中编辑文字，勾选“书写到”组框中的“文本区1”和（或）“文本区2”复选框后单击“提交”按钮，程序会自动将文本框中的文字“抄写”到对应的用户勾选的文本区中去。
代码实现如下：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms; namespace DelegateDemo
{
public partial class FrmMain : Form
{
public FrmMain()
{
InitializeComponent();
} //1、定义委托
private delegate void WriteToTextBox(string strTxt);
//2、声明委托
private WriteToTextBox writeToTextBox; /// <summary>
/// 提交
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btn_OK_Click(object sender, EventArgs e)
{
if (chbOne.Checked)
{
gbJobOne.Text = "运行中......";
gbJobOne.Refresh();
txtJobOne.Clear();
//3、实例化委托
writeToTextBox = new WriteToTextBox(WriteTextBox1);
//4、将委托作为方法的参数进行传递
WriteText(writeToTextBox);
gbJobOne.Text = "任务1完成";
}
if (chbTwo.Checked)
{ gbJobTwo.Text = "运行中......";
gbJobTwo.Refresh();
txtJobTwo.Clear();
//3、实例化委托
writeToTextBox = new WriteToTextBox(WriteTextBox2);
//4、将委托作为方法的参数进行传递
WriteText(writeToTextBox);
gbJobTwo.Text = "任务2完成";
}
} private void WriteText(WriteToTextBox writeMethod)
{
string strData = this.txt_Input.Text;
writeMethod(strData);
}
private void WriteTextBox1(string strTxt)
{
this.txtJobOne.Text = strTxt;
} private void WriteTextBox2(string strTxt)
{
this.txtJobTwo.Text = strTxt;
} /// <summary>
/// 窗体加载事件
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void FrmMain_Load(object sender, EventArgs e)
{
//设置文本框获取焦点
this.ActiveControl = this.txt_Input;
//this.txt_Input.Focus();
}
}
}
特性2：多线程
多线程的具体介绍请参考博文：http://www.cnblogs.com/dotnet261010/p/6159984.html
使用多线程实现上一节的程序，代码如下：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;//引入多线程的命名空间 namespace DelegateDemo
{
public partial class FrmMain : Form
{
public FrmMain()
{
InitializeComponent();
} //1、定义委托
private delegate void WriteToTextBox(string strTxt);
//2、声明委托
private WriteToTextBox writeToTextBox; /// <summary>
/// 提交
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btn_OK_Click(object sender, EventArgs e)
{
//创建线程1
Thread thread1 = new Thread(new ThreadStart(ExecuteTsk1));
//启动线程1
thread1.Start(); //创建线程2
Thread thread2 = new Thread(new ThreadStart(ExecuteTsk2));
//启动线程2
thread2.Start(); } private void ExecuteTsk1()
{
if (chbOne.Checked)
{
gbJobOne.Text = "运行中......";
gbJobOne.Refresh();
txtJobOne.Clear();
//3、实例化委托
writeToTextBox = new WriteToTextBox(WriteTextBox1);
//4、将委托作为方法的参数进行传递
WriteText(writeToTextBox);
gbJobOne.Text = "任务1完成";
}
} private void ExecuteTsk2()
{
if (chbTwo.Checked)
{ gbJobTwo.Text = "运行中......";
gbJobTwo.Refresh();
txtJobTwo.Clear();
//3、实例化委托
writeToTextBox = new WriteToTextBox(WriteTextBox2);
//4、将委托作为方法的参数进行传递
WriteText(writeToTextBox);
gbJobTwo.Text = "任务2完成";
}
} private void WriteText(WriteToTextBox writeMethod)
{
string strData = this.txt_Input.Text;
writeMethod(strData);
}
private void WriteTextBox1(string strTxt)
{
this.txtJobOne.Text = strTxt;
} private void WriteTextBox2(string strTxt)
{
this.txtJobTwo.Text = strTxt;
} /// <summary>
/// 窗体加载事件
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void FrmMain_Load(object sender, EventArgs e)
{
//设置文本框获取焦点
this.ActiveControl = this.txt_Input;
//允许跨线程调用
Control.CheckForIllegalCrossThreadCalls = false;
}
}
}
特性3：C#方法回调
C#回调的具体介绍请参照博文：http://www.cnblogs.com/dotnet261010/p/6159984.html
使用委托、多线程和C#的方法回调机制实现上一节的程序，代码如下：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;//引入多线程的命名空间 namespace DelegateDemo
{
public partial class FrmMain : Form
{
public FrmMain()
{
InitializeComponent();
} //1、定义委托
private delegate void WriteToTextBox(string strTxt);
//2、声明委托
private WriteToTextBox writeToTextBox; //定义并声明操作文本区1的回调
private delegate void WriteTxtJobOneCallBack(string strValue);
WriteTxtJobOneCallBack writeTxtJobOneCallBack; //定义并声明操作文本区2的回调
private delegate void WriteTxtJobTwoCallBack(string strValue);
WriteTxtJobOneCallBack writeTxtJobTwoCallBack; //定义并声明操作"任务1"分组框的回调
private delegate void ShowGroupOneCallBack(string strValue);
ShowGroupOneCallBack showGroupOneCallBack; //定义并声明操作"任务2"分组框的回调
private delegate void ShowGroupTwoCallBack(string strValue);
ShowGroupOneCallBack showGroupTwoCallBack; /// <summary>
/// 提交
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btn_OK_Click(object sender, EventArgs e)
{
//创建线程1
Thread thread1 = new Thread(new ThreadStart(ExecuteTsk1));
//启动线程1
thread1.Start(); //创建线程2
Thread thread2 = new Thread(new ThreadStart(ExecuteTsk2));
//启动线程2
thread2.Start(); } private void ExecuteTsk1()
{
if (chbOne.Checked)
{
//3、实例化委托
writeToTextBox = new WriteToTextBox(WriteTextBox1);
//4、将委托作为方法的参数进行传递
WriteText(writeToTextBox);
//使用回调
this.gbJobOne.Invoke(showGroupOneCallBack, "任务1");
}
} private void ExecuteTsk2()
{
if (chbTwo.Checked)
{
//3、实例化委托
writeToTextBox = new WriteToTextBox(WriteTextBox2);
//4、将委托作为方法的参数进行传递
WriteText(writeToTextBox);
//使用回调
this.gbJobTwo.Invoke(showGroupTwoCallBack, "任务2");
}
} /// <summary>
/// 执行自定义委托
/// </summary>
/// <param name="writeMethod"></param>
private void WriteText(WriteToTextBox writeMethod)
{
string strData = this.txt_Input.Text;
writeMethod(strData);
} /// <summary>
/// 给文本区1赋值
/// </summary>
/// <param name="strTxt"></param>
private void WriteTextBox1(string strTxt)
{
//使用回调
this.txtJobOne.Invoke(writeTxtJobOneCallBack, strTxt);
} /// <summary>
/// 给文本区2赋值
/// </summary>
/// <param name="strTxt"></param>
private void WriteTextBox2(string strTxt)
{
//使用回调
this.txtJobTwo.Invoke(writeTxtJobTwoCallBack, strTxt);
} /// <summary>
/// 窗体加载事件
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void FrmMain_Load(object sender, EventArgs e)
{
//设置文本框获取焦点
this.ActiveControl = this.txt_Input; //实例化回调
writeTxtJobOneCallBack = new WriteTxtJobOneCallBack(WriteToTextJobOne);
writeTxtJobTwoCallBack = new WriteTxtJobOneCallBack(WriteToTextJobTwo);
showGroupOneCallBack = new ShowGroupOneCallBack(ShowGroupOne);
showGroupTwoCallBack = new ShowGroupOneCallBack(ShowGroupTwo); } /// <summary>
/// 操作文本区1的回调要执行的方法
/// </summary>
/// <param name="strValue"></param>
private void WriteToTextJobOne(string strValue)
{
this.txtJobOne.Text = strValue;
} /// <summary>
/// 操作文本区2的回调要执行的方法
/// </summary>
/// <param name="strValue"></param>
private void WriteToTextJobTwo(string strValue)
{
this.txtJobTwo.Text = strValue;
} /// <summary>
/// 操作"任务1"分组框的回调要执行的方法
/// </summary>
/// <param name="strValue"></param>
private void ShowGroupOne(string strValue)
{
this.gbJobOne.Text = strValue;
} /// <summary>
/// 操作"任务2"分组框的回调要执行的方法
/// </summary>
/// <param name="strValue"></param>
private void ShowGroupTwo(string strValue)
{
this.gbJobTwo.Text = strValue;
}
}
}