步步为营-26-多播委托

事件本质:多播委托;多播委托本质:一个委托指向多个函数

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Delegate_DuoBo
{
    //1 声明一个委托无参数,无返回值
    public delegate void DuoBoDelegate ();
    class Program
    {
        static void Main(string[] args)
        {
            DuoBoDelegate del = new DuoBoDelegate(Test1);

            del += Test3;
            del += Test4;
            del += Test2;
            del -= Test4;
            del();
            Console.Read();
        }

        //根据委托定义方法
        public static void Test1() 
        {
            Console.WriteLine("Test1");
        }
        public static void Test2()
        {
            Console.WriteLine("Test2");
        }
        public static void Test3()
        {
            Console.WriteLine("Test3");
        }
        public static void Test4()
        {
            Console.WriteLine("Test4");
        }
    }
}

窗体间通过委托传值

创建两个Form

form1需要将ShowText方法传递给Form2,所以需要

1在Form2中定义委托用于接受Form1中的ShowText方法

2同时修改构造函数,

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 Delegate_Window
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnShowWinfrom2_Click(object sender, EventArgs e)
        {
           //把方法传给form2
            Form form2 = new Form2(ShowText);
            form2.Show();
            
        }

        public void ShowText(string str) 
        {
            lbl.Text = str;
        }
    }
}

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 Delegate_Window
{
    public delegate void del(string str);
    public partial class Form2 : Form
    {
        //存储Form1传过来的委托
        private del _del;
        public Form2(del dlegt)
        {
            InitializeComponent();
            this._del = dlegt;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this._del(textBox1.Text.Trim());
        }

        private void Form2_Load(object sender, EventArgs e)
        {

        }
    }
}