C#網絡編程中常用特性介紹

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特性一：委托

委托是C#語言中特有的概念，相當於C/C++中的函數指針，與C/C++中函數指針的不同之處是：委托是面向對象的、類型安全的和保險的，是引用類型。因此，對委托的使用要

“先定義、後聲明，接著實例化、然後作為參數傳遞給方法，最後才能使用”。

1、定義委托使用關鍵字delegate:

delegate  void SomeDelegate(type1 para1,……typen paran);

2、聲明委托：

SomeDelegate  d;

3、實例化委托：

d=new SomeDelegate(obj.InstanceMethod);

其中obj是對象，InstanceMethod是它的實例方法。

4、作為參數傳遞給方法

someMethod(d);

5、最後在此方法的實現代碼中使用委托

private  void  someMethod(SomeDelegate  someDelegate)
{
   .....
   //使用委托
  someDelegate(arg1,arg2,....,argn);
  ...... 
}

通過委托SomeDelegate實現對方法InstanceMethod的調用，調用還必須有一個前提條件：方法InstanceMethod有參數且和定義SomeDelegate的參數一致，並且返回類型相同（本例中為void）。方法InstanceMethod的定義：

private  void  InstanceMethod(type1 para1,type2 para2,......,typen paran)
{
   //方法體
  .....
}

委托的實例化中的參數既可以是實例方法，也可以是靜態方法。

使用委托實現“文字抄寫員”的小程序，界面如下：

在下方文本框中編輯文字，勾選“書寫到”組框中的“文本區1”和（或）“文本區2”復選框後單擊“提交”按鈕，程序會自動將文本框中的文字“抄寫”到對應的用戶勾選的文本區中去。

代碼實現如下：

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、定義委托
        private delegate void WriteToTextBox(string strTxt);
        //2、聲明委托
        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 = "運行中......";
                gbJobOne.Refresh();
                txtJobOne.Clear();
                //3、實例化委托
                writeToTextBox = new WriteToTextBox(WriteTextBox1);
                //4、將委托作為方法的參數進行傳遞
                WriteText(writeToTextBox);
                gbJobOne.Text = "任務1完成";
            }
            if (chbTwo.Checked)
            {

                gbJobTwo.Text = "運行中......";
                gbJobTwo.Refresh();
                txtJobTwo.Clear();
                //3、實例化委托
                writeToTextBox = new WriteToTextBox(WriteTextBox2);
                //4、將委托作為方法的參數進行傳遞
                WriteText(writeToTextBox);
                gbJobTwo.Text = "任務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>
        /// 窗體加載事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void FrmMain_Load(object sender, EventArgs e)
        {
            //設置文本框獲取焦點
            this.ActiveControl = this.txt_Input;
            //this.txt_Input.Focus();
        }
    }
}

特性2：多線程

多線程的具體介紹請參考博文：https://www.jb51.net/article/238731.htm

使用多線程實現上一節的程序，代碼如下：

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;//引入多線程的命名空間

namespace DelegateDemo
{
    public partial class FrmMain : Form
    {
        public FrmMain()
        {
            InitializeComponent();
        }

        //1、定義委托
        private delegate void WriteToTextBox(string strTxt);
        //2、聲明委托
        private WriteToTextBox writeToTextBox;

        /// <summary>
        /// 提交
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btn_OK_Click(object sender, EventArgs e)
        {
           //創建線程1
            Thread thread1 = new Thread(new ThreadStart(ExecuteTsk1));
            //啟動線程1
            thread1.Start();

            //創建線程2
            Thread thread2 = new Thread(new ThreadStart(ExecuteTsk2));
            //啟動線程2
            thread2.Start();

        }


        private void ExecuteTsk1()
        {
            if (chbOne.Checked)
            {
                gbJobOne.Text = "運行中......";
                gbJobOne.Refresh();
                txtJobOne.Clear();
                //3、實例化委托
                writeToTextBox = new WriteToTextBox(WriteTextBox1);
                //4、將委托作為方法的參數進行傳遞
                WriteText(writeToTextBox);
                gbJobOne.Text = "任務1完成";
            }
        }

        private void ExecuteTsk2()
        {
            if (chbTwo.Checked)
            {

                gbJobTwo.Text = "運行中......";
                gbJobTwo.Refresh();
                txtJobTwo.Clear();
                //3、實例化委托
                writeToTextBox = new WriteToTextBox(WriteTextBox2);
                //4、將委托作為方法的參數進行傳遞
                WriteText(writeToTextBox);
                gbJobTwo.Text = "任務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>
        /// 窗體加載事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void FrmMain_Load(object sender, EventArgs e)
        {
            //設置文本框獲取焦點
            this.ActiveControl = this.txt_Input;
            //允許跨線程調用
            Control.CheckForIllegalCrossThreadCalls = false;
        }
    }
}

特性3：C#方法回調

C#回調的具體介紹請參照博文：https://www.jb51.net/article/238731.htm#_label3

使用委托、多線程和C#的方法回調機制實現上一節的程序，代碼如下：

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;//引入多線程的命名空間

namespace DelegateDemo
{
    public partial class FrmMain : Form
    {
        public FrmMain()
        {
            InitializeComponent();
        }

        //1、定義委托
        private delegate void WriteToTextBox(string strTxt);
        //2、聲明委托
        private WriteToTextBox writeToTextBox;

        //定義並聲明操作文本區1的回調
        private delegate void WriteTxtJobOneCallBack(string strValue);
        WriteTxtJobOneCallBack writeTxtJobOneCallBack;

        //定義並聲明操作文本區2的回調
        private delegate void WriteTxtJobTwoCallBack(string strValue);
        WriteTxtJobOneCallBack writeTxtJobTwoCallBack;

        //定義並聲明操作"任務1"分組框的回調
        private delegate void ShowGroupOneCallBack(string strValue);
        ShowGroupOneCallBack showGroupOneCallBack;

        //定義並聲明操作"任務2"分組框的回調
        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)
        {
           //創建線程1
            Thread thread1 = new Thread(new ThreadStart(ExecuteTsk1));
            //啟動線程1
            thread1.Start();

            //創建線程2
            Thread thread2 = new Thread(new ThreadStart(ExecuteTsk2));
            //啟動線程2
            thread2.Start();

        }


        private void ExecuteTsk1()
        {
            if (chbOne.Checked)
            {
                //3、實例化委托
                writeToTextBox = new WriteToTextBox(WriteTextBox1);
                //4、將委托作為方法的參數進行傳遞
                WriteText(writeToTextBox);
                //使用回調
                this.gbJobOne.Invoke(showGroupOneCallBack, "任務1");
            }
        }

        private void ExecuteTsk2()
        {
            if (chbTwo.Checked)
            {
                //3、實例化委托
                writeToTextBox = new WriteToTextBox(WriteTextBox2);
                //4、將委托作為方法的參數進行傳遞
                WriteText(writeToTextBox);
                //使用回調
                this.gbJobTwo.Invoke(showGroupTwoCallBack, "任務2");
            }
        }

        /// <summary>
        /// 執行自定義委托
        /// </summary>
        /// <param name="writeMethod"></param>
        private void WriteText(WriteToTextBox writeMethod)
        {
            string strData = this.txt_Input.Text;
            writeMethod(strData);
        }

        /// <summary>
        /// 給文本區1賦值
        /// </summary>
        /// <param name="strTxt"></param>
        private void WriteTextBox1(string strTxt)
        {
            //使用回調
            this.txtJobOne.Invoke(writeTxtJobOneCallBack, strTxt);
        }

        /// <summary>
        /// 給文本區2賦值
        /// </summary>
        /// <param name="strTxt"></param>
        private void WriteTextBox2(string strTxt)
        {
            //使用回調
            this.txtJobTwo.Invoke(writeTxtJobTwoCallBack, strTxt);
        }

        /// <summary>
        /// 窗體加載事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void FrmMain_Load(object sender, EventArgs e)
        {
            //設置文本框獲取焦點
            this.ActiveControl = this.txt_Input;

            //實例化回調
            writeTxtJobOneCallBack = new WriteTxtJobOneCallBack(WriteToTextJobOne);
            writeTxtJobTwoCallBack = new WriteTxtJobOneCallBack(WriteToTextJobTwo);
            showGroupOneCallBack = new ShowGroupOneCallBack(ShowGroupOne);
            showGroupTwoCallBack = new ShowGroupOneCallBack(ShowGroupTwo);

        }

        /// <summary>
        /// 操作文本區1的回調要執行的方法
        /// </summary>
        /// <param name="strValue"></param>
        private void WriteToTextJobOne(string strValue)
        {
            this.txtJobOne.Text = strValue;
        }

        /// <summary>
        /// 操作文本區2的回調要執行的方法
        /// </summary>
        /// <param name="strValue"></param>
        private void WriteToTextJobTwo(string strValue)
        {
            this.txtJobTwo.Text = strValue;
        }

        /// <summary>
        /// 操作"任務1"分組框的回調要執行的方法
        /// </summary>
        /// <param name="strValue"></param>
        private void ShowGroupOne(string strValue)
        {
            this.gbJobOne.Text = strValue;
        }

        /// <summary>
        /// 操作"任務2"分組框的回調要執行的方法
        /// </summary>
        /// <param name="strValue"></param>
        private void ShowGroupTwo(string strValue)
        {
            this.gbJobTwo.Text = strValue;
        }
    }
}

到此這篇關於C#網絡編程中常用特性的文章就介紹到這瞭。希望對大傢的學習有所幫助，也希望大傢多多支持WalkonNet。

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