步步为营-44-窗体之间传值--观察者模式

说明 :观察者模式又叫发布-订阅模式,其中又涉及到中介者模式

1 结构

2 创建Main窗体(中介者),ChildForm1(发布者),ChildForm2(订阅者),ChildForm3(订阅者),

　　2.1 ChildForm1中添加按钮,当按钮被点击是ChildForm2(订阅者),ChildForm3(订阅者),的文本框汇中获取信息

　　2.2 定义接口

　　public interface IMessageOn
   　　{
     　　  void RecieveMsg(string str);
   　　}

　　2.3 在发布者ChildForm1中创建MessageOnList集合

　　2.4 订阅者ChildForm2,ChildForm3中实现接口

  　　public void RecieveMsg(string str)
        {
            this.txtGetTime.Text = str;
        }

　　2.5 中介者Main把 订阅者放入到发布者的MessageONList集合中

  　　ChildForm2 frm2 = new ChildForm2();
            //2把订阅者放入到发布者的MessageONList集合中
            frm1.MessageOnList.Add(frm2);
            //3显示窗体
            frm2.Show();

　　2.6 遍历集合,通知所有的观察者

　　 foreach (var MessageOn in MessageOnList)
            {
                MessageOn.RecieveMsg(txtSendMsg.Text);
            }

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 中介者_订阅者
{
    public partial class Main : Form
    {
        public Main()
        {
            InitializeComponent();
        }

        private void btnOpenForm_Click(object sender, EventArgs e)
        {
            //1创建窗体
            ChildForm1 frm1 = new ChildForm1();
            frm1.Show();

            ChildForm2 frm2 = new ChildForm2(); 
            //2把订阅者放入到发布者的MessageONList集合中
            frm1.MessageOnList.Add(frm2);
            //3显示窗体
            frm2.Show();

           
            ChildForm3 frm3 = new ChildForm3();
            frm1.MessageOnList.Add(frm3);
            frm3.Show();

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

namespace 中介者_订阅者
{
   public interface IMessageOn
   {
       void RecieveMsg(string str);
   }
}
IMessageOn
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 中介者_订阅者
{
    public partial class ChildForm1 : Form
    {
        public ChildForm1()
        {
            InitializeComponent();
            MessageOnList = new List<IMessageOn>();
        }
        public List<IMessageOn> MessageOnList { set; get; }

        private void btnSendTime_Click(object sender, EventArgs e)
        {
            foreach (var MessageOn in MessageOnList)
            {
                MessageOn.RecieveMsg(txtSendMsg.Text);
            }
        }


    }
}
ChildForm1 
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 中介者_订阅者
{
    public partial class ChildForm2 : Form,IMessageOn
    {
        public ChildForm2()
        {
            InitializeComponent();
        }

        public void RecieveMsg(string str)
        {
            this.txtGetTime.Text = str;
        }
    }
}
ChildForm2 
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 中介者_订阅者
{
    public partial class ChildForm3 : Form,IMessageOn
    {
        public ChildForm3()
        {
            InitializeComponent();
        }

        public void RecieveMsg(string str)
        {
            this.txtGetTime.Text = str;
        }
}
}
ChildForm3

通过中介者,将发布者和订阅者实现了解耦

3 通过委托实现

3.1 在ChildForm1中声明委托类型

    public delegate void SendMsgDel(string sendMsg);

3.2 在ChildForm1中定义委托实例

　　 //02-02定义委托实例
        public SendMsgDel SendMsgDelInstance { set; get; }

3.3   在ChildForm2中定义委托实现方法
        public void RecieveMsgByDel(string str)
        {
            this.txtGetTime.Text = str;
        }

3.4 Main中将观察者的方法注册到ChildForm1中的委托中去

            frm1.SendMsgDelInstance += frm2.RecieveMsgByDel;
 3.5 单击按钮触发事件

 private void btnDelegate_Click(object sender, EventArgs e)
        {
            SendMsgDelInstance(txtSendMsg.Text);
        }

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 中介者_订阅者
{
    public partial class Main : Form
    {
        public Main()
        {
            InitializeComponent();
        }

        private void btnOpenForm_Click(object sender, EventArgs e)
        {
            //1创建窗体
            ChildForm1 frm1 = new ChildForm1();
            frm1.Show();

            ChildForm2 frm2 = new ChildForm2(); 
            //2把订阅者放入到发布者的MessageONList集合中
            frm1.MessageOnList.Add(frm2);
            frm1.SendMsgDelInstance += frm2.RecieveMsgByDel;
            //3显示窗体
            frm2.Show();

           
            ChildForm3 frm3 = new ChildForm3();
            frm1.MessageOnList.Add(frm3);
            //2-2将观察者的方法注册到委托中去
            frm1.SendMsgDelInstance += frm3.RecieveMsgByDel;
            frm3.Show();

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

namespace 中介者_订阅者
{
   public interface IMessageOn
   {
       void RecieveMsg(string str);
   }
}
IMessageOn
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 中介者_订阅者
{
    //02-01定义委托
    public delegate void SendMsgDel(string sendMsg);
    public partial class ChildForm1 : Form
    {
        public ChildForm1()
        {
            InitializeComponent();
            MessageOnList = new List<IMessageOn>();
        }
        #region 01通过发布者模式实现
        public List<IMessageOn> MessageOnList { set; get; }

        private void btnSendTime_Click(object sender, EventArgs e)
        {
            foreach (var MessageOn in MessageOnList)
            {
                MessageOn.RecieveMsg(txtSendMsg.Text);
            }
        } 
        #endregion

        #region 02通过委托实现
        //02-02定义委托实例
        public SendMsgDel SendMsgDelInstance { set; get; }

        private void btnDelegate_Click(object sender, EventArgs e)
        {
            SendMsgDelInstance(txtSendMsg.Text);
        } 
        #endregion


    }
}
ChildForm1 
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 中介者_订阅者
{
    public partial class ChildForm2 : Form,IMessageOn
    {
        public ChildForm2()
        {
            InitializeComponent();
        }

        #region 01接口实现发布者模式 方法
        public void RecieveMsg(string str)
        {
            this.txtGetTime.Text = str;
        } 
        #endregion

        #region 02委托实现方法
        public void RecieveMsgByDel(string str)
        {
            this.txtGetTime.Text = str;
        }
        #endregion
    }
}
ChildForm2 
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 中介者_订阅者
{
    public partial class ChildForm3 : Form,IMessageOn
    {
        public ChildForm3()
        {
            InitializeComponent();
        }
        #region 01接口实现发布者模式 方法
        public void RecieveMsg(string str)
        {
            this.txtGetTime.Text = str;
        }
        #endregion

        #region 02委托实现方法
        public void RecieveMsgByDel(string str)
        {
            this.txtGetTime.Text = str;
        }
        #endregion
}
}
ChildForm3

但是,使用委托有一缺陷==>不安全,
例如,在Main中创建完窗体后直接加一句

 frm1.SendMsgDelInstance("委托实现不安全");

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 中介者_订阅者
{
    public partial class Main : Form
    {
     
        public Main()
        {
            InitializeComponent();
        }

        private void btnOpenForm_Click(object sender, EventArgs e)
        {
            //1创建窗体
            ChildForm1 frm1 = new ChildForm1();
            frm1.Show();

            ChildForm2 frm2 = new ChildForm2(); 
            //2-1把订阅者放入到发布者的MessageONList集合中---接口形式注册
            frm1.MessageOnList.Add(frm2);
            frm1.SendMsgDelInstance += frm2.RecieveMsgByDel;
            frm1.SendMsgDelEven += frm2.RecieveMsgByEvent;

            //3显示窗体
            frm2.Show();

           
            ChildForm3 frm3 = new ChildForm3();
            frm1.MessageOnList.Add(frm3);
            //2-2将观察者的方法注册到委托中去----委托形式注册
            frm1.SendMsgDelInstance += frm3.RecieveMsgByDel;
            //2-3将观察者的方法注册到事件中去----事件形式注册
            frm1.SendMsgDelEven += frm3.RecieveMsgByEvent;
            frm3.Show();

            frm1.SendMsgDelInstance("委托实现不安全");
            //frm1.SendMsgDelEven("事件事件安全");
        }
    }
}
View Code

4通过事件实现

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 中介者_订阅者
{
    public partial class Main : Form
    {
     
        public Main()
        {
            InitializeComponent();
        }

        private void btnOpenForm_Click(object sender, EventArgs e)
        {
            //1创建窗体
            ChildForm1 frm1 = new ChildForm1();
            frm1.Show();

            ChildForm2 frm2 = new ChildForm2(); 
            //2-1把订阅者放入到发布者的MessageONList集合中---接口形式注册
            frm1.MessageOnList.Add(frm2);
            frm1.SendMsgDelInstance += frm2.RecieveMsgByDel;
            frm1.SendMsgDelEven += frm2.RecieveMsgByEvent;

            //3显示窗体
            frm2.Show();

           
            ChildForm3 frm3 = new ChildForm3();
            frm1.MessageOnList.Add(frm3);
            //2-2将观察者的方法注册到委托中去----委托形式注册
            frm1.SendMsgDelInstance += frm3.RecieveMsgByDel;
            //2-3将观察者的方法注册到事件中去----事件形式注册
            frm1.SendMsgDelEven += frm3.RecieveMsgByEvent;
            frm3.Show();

            frm1.SendMsgDelInstance("委托实现不安全");
            //frm1.SendMsgDelEven("事件事件安全");
        }
    }
}
Main 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 中介者_订阅者
{
   public interface IMessageOn
   {
       void RecieveMsg(string str);
   }
}
IMessageOn
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 中介者_订阅者
{
    //02-01定义委托
    public delegate void SendMsgDel(string sendMsg);
    public partial class ChildForm1 : Form
    {
        public ChildForm1()
        {
            InitializeComponent();
            MessageOnList = new List<IMessageOn>();
        }
        #region 01通过发布者模式实现
        public List<IMessageOn> MessageOnList { set; get; }

        private void btnSendTime_Click(object sender, EventArgs e)
        {
            foreach (var MessageOn in MessageOnList)
            {
                MessageOn.RecieveMsg(txtSendMsg.Text);
            }
        } 
        #endregion

        #region 02通过委托实现
        //02-02定义委托实例
        public SendMsgDel SendMsgDelInstance { set; get; }

        private void btnDelegate_Click(object sender, EventArgs e)
        {
            SendMsgDelInstance(txtSendMsg.Text);
        } 
        #endregion

        #region 03事件实现
        public event SendMsgDel SendMsgDelEven;
        private void btnEvent_Click(object sender, EventArgs e)
        {
            if (SendMsgDelEven!=null)
            {
                SendMsgDelEven(txtSendMsg.Text);
            }
        }
        #endregion

      
    }
}
ChildForm1 
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 中介者_订阅者
{
    public partial class ChildForm2 : Form,IMessageOn
    {
        public ChildForm2()
        {
            InitializeComponent();
        }

        #region 01接口实现发布者模式 方法
        public void RecieveMsg(string str)
        {
            this.txtGetTime.Text = str;
        } 
        #endregion

        #region 02委托实现方法
        public void RecieveMsgByDel(string str)
        {
            this.txtGetTime.Text = str;
        }
        #endregion

        #region 03事件实现方法
        public void RecieveMsgByEvent(string str)
        {
            this.txtGetTime.Text = str;
        }
        #endregion
    }
}
ChildForm2
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 中介者_订阅者
{
    public partial class ChildForm3 : Form,IMessageOn
    {
        public ChildForm3()
        {
            InitializeComponent();
        }
        #region 01接口实现发布者模式 方法
        public void RecieveMsg(string str)
        {
            this.txtGetTime.Text = str;
        }
        #endregion

        #region 02委托实现方法
        public void RecieveMsgByDel(string str)
        {
            this.txtGetTime.Text = str;
        }
        #endregion
        #region 03事件实现方法
        public void RecieveMsgByEvent(string str)
        {
            this.txtGetTime.Text = str;
        }
        #endregion
}
}
View Code
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原文地址：https://www.cnblogs.com/YK2012/p/6806842.html