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迭代器 计算机科学设计模式
中介者 		备忘录
目录

这种模式定义了一个封装一组对象之间如何交互的对象。中介者通过阻止对象显式地相互引用来促进松散耦合，并且它允许你独立地改变它们的交互。这种模式有助于建模一个在运行时负责控制和协调一组其他对象交互的类的对象。

参与者

中介者 - 定义同事对象之间通信的接口。具体中介者 - 实现中介者接口并协调同事对象之间的通信。它了解所有同事及其在相互通信方面的目的。具体同事 - 通过其中介者与其他同事通信。

示例

Clipboard

待办事项
查找示例。


成本

这种模式并不昂贵，因为它没有太多限制。

创建

这种模式易于创建。

维护

这种模式易于维护。

移除

每个对象都可以通过重构轻松地转换为另一种结构。

建议

  • 在迭代器类的名称中添加中介者一词，以向其他开发人员指示模式的使用。

实现

Java 实现
// Colleague interface
interface Command {
    void execute();
}

import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
// Concrete mediator
class Mediator {
    BtnView btnView;
    BtnSearch btnSearch;
    BtnBook btnBook;
    LblDisplay show;
    //....
    void registerView(BtnView v) {
        btnView = v;
    }
    void registerSearch(BtnSearch s) {
        btnSearch = s;
    }
    void registerBook(BtnBook b) {
        btnBook = b;
    }
    void registerDisplay(LblDisplay d) {
        show = d;
    }
    void book() {
        btnBook.setEnabled(false);
        btnView.setEnabled(true);
        btnSearch.setEnabled(true);
        show.setText("booking...");
    }
    void view() {
        btnView.setEnabled(false);
        btnSearch.setEnabled(true);
        btnBook.setEnabled(true);
        show.setText("viewing...");
    }
    void search() {
        btnSearch.setEnabled(false);
        btnView.setEnabled(true);
        btnBook.setEnabled(true);
        show.setText("searching...");
    }
   
}

import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
// A concrete colleague
class BtnView extends JButton implements Command {
    Mediator med;
    BtnView(ActionListener al, Mediator m) {
        super("View");
        addActionListener(al);
        med = m;
        med.registerView(this);
    }
    public void execute() {
        med.view();
    }
   
}

import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
// A concrete colleague
class BtnSearch extends JButton implements Command {
    Mediator med;
    BtnSearch(ActionListener al, Mediator m) {
        super("Search");
        addActionListener(al);
        med = m;
        med.registerSearch(this);
    }
    public void execute() {
        med.search();
    }
   
}

import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
// A concrete colleague
class BtnBook extends JButton implements Command {
    Mediator med;
    BtnBook(ActionListener al, Mediator m) {
        super("Book");
        addActionListener(al);
        med = m;
        med.registerBook(this);
    }
    public void execute() {
        med.book();
    }
}

import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
class LblDisplay extends JLabel {
    Mediator med;
    LblDisplay(Mediator m) {
        super("Just start...");
        med = m;
        med.registerDisplay(this);
        setFont(new Font("Arial", Font.BOLD, 24));
    }
}

import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
class MediatorDemo extends JFrame implements ActionListener {
    Mediator med = new Mediator();
    MediatorDemo() {
        JPanel p = new JPanel();
        p.add(new BtnView(this, med));
        p.add(new BtnBook(this, med));
        p.add(new BtnSearch(this, med));
        getContentPane().add(new LblDisplay(med), "North");
        getContentPane().add(p, "South");
        setSize(400, 200);
        setVisible(true);
    }
    public void actionPerformed(ActionEvent ae) {
        Command comd = (Command) ae.getSource();
        comd.execute();
    }
    public static void main(String[] args) {
        new MediatorDemo();
    }
}
C# 实现
using System;
using System.Collections;
  class MainApp
  {
    static void Main()
    {
      ConcreteMediator m = new ConcreteMediator();
      ConcreteColleague1 c1 = new ConcreteColleague1(m);
      ConcreteColleague2 c2 = new ConcreteColleague2(m);
      m.Colleague1 = c1;
      m.Colleague2 = c2;
      c1.Send("How are you?");
      c2.Send("Fine, thanks");
      // Wait for user
      Console.Read();
    }
  }
  // "Mediator"
  abstract class Mediator
  {
    public abstract void Send(string message,
      Colleague colleague);
  }
  // "ConcreteMediator"
  class ConcreteMediator : Mediator
  {
    private ConcreteColleague1 colleague1;
    private ConcreteColleague2 colleague2;
    public ConcreteColleague1 Colleague1
    {
      set{ colleague1 = value; }
    }
    public ConcreteColleague2 Colleague2
    {
      set{ colleague2 = value; }
    }
    public override void Send(string message,
      Colleague colleague)
    {
      if (colleague == colleague1)
      {
        colleague2.Notify(message);
      }
      else
      {
        colleague1.Notify(message);
      }
    }
  }
  // "Colleague"
  abstract class Colleague
  {
    protected Mediator mediator;
    // Constructor
    public Colleague(Mediator mediator)
    {
      this.mediator = mediator;
    }
  }
  // "ConcreteColleague1"
  class ConcreteColleague1 : Colleague
  {
    // Constructor
    public ConcreteColleague1(Mediator mediator)
      : base(mediator)
    {
    }
    public void Send(string message)
    {
      mediator.Send(message, this);
    }
    public void Notify(string message)
    {
      Console.WriteLine("Colleague1 gets message: "
        + message);
    }
  }
  // "ConcreteColleague2"
  class ConcreteColleague2 : Colleague
  {
    // Constructor
    public ConcreteColleague2(Mediator mediator)
      : base(mediator)
    {
    }
    public void Send(string message)
    {
      mediator.Send(message, this);
    }
    public void Notify(string message)
    {
      Console.WriteLine("Colleague2 gets message: "
        + message);
    }
  }


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待办事项
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迭代器 计算机科学设计模式
中介者 		备忘录


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