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 &
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”。
delegate void SomeDelegate(type1 para1,......typen paran);
SomeDelegate d;
d=new SomeDelegate(obj.InstanceMethod);
其中obj是对象,InstanceMethod是它的实例方法。
someMethod(d);
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();
}
}
}
多线程的具体介绍请参考博文:https://www.jb51.net/article/238731.htm
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;
}
}
}
C#回调的具体介绍请参照博文:Https://www.jb51.net/article/238731.htm#_label3
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;
}
}
}
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本文标题: C#网络编程中常用特性介绍
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