中介者模式 Mediator Pattern

一、什么是中介者模式
Mediator模式也叫中介者模式，是由GoF提出的23种软件设计模式的一种。Mediator模式是行为模式之一，在Mediator模式中，类之间的交互行为被统一放在Mediator的对象中，对象通过Mediator对象同其他对象交互，Mediator对象起着控制器的作用。


二、中介者模式的结构



三、中介者模式的角色和职责

mediator

中介者类的抽象父类。

concreteMediator

具体的中介者类。

colleague

关联类的抽象父类。

concreteColleague

具体的关联类。

四、中介者模式的优点
1. 将系统按功能分割成更小的对象，符合类的最小设计原则
2. 对关联对象的集中控制
3. 减小类的耦合程度，明确类之间的相互关系：当类之间的关系过于复杂时，其中任何一个类的修改都会影响到其他类，不符合类的设计的开闭原则 ，而Mediator模式将原来相互依存的多对多的类之间的关系简化为Mediator控制类与其他关联类的一对多的关系，当其中一个类修改时，可以对其他关联类不产生影响（即使有修改，也集中在Mediator控制类）。
4. 有利于提高类的重用性

未运用中介模式前的实现：

Person.java
package com.ibeifeng.ex1; 

public abstract class Person { 
    private String name; 
    private int condition; 
 
    public Person(String name, int condition) { 
        this.name = name; 
        this.condition = condition; 
    } 
 
    public String getName() { 
        return name; 
    } 
    public void setName(String name) { 
        this.name = name; 
    } 
    public int getCondition() { 
        return condition; 
    } 
 
    public void setCondition(int condition) { 
        this.condition = condition; 
    } 
 
    public abstract void getPartner(Person person); 
 
}
Man.java
package com.ibeifeng.ex1; 

public class Man extends Person { 
 
    public Man(String name, int condition) { 
        super(name, condition); 
    } 
 
    public void getPartner(Person person) { 
        if(person instanceof Man) { 
            System.out.println("汗，我不是同性恋！"); 
        } else { 
            if(this.getCondition() == person.getCondition()) { 
                System.out.println(this.getName() + "和" + person.getName() + "绝配"); 
            } else { 
                System.out.println(this.getName() + "和" + person.getName() + "不相配"); 
            } 
        } 
    } 
 
}
Woman.java
package com.ibeifeng.ex1; 

public class Woman extends Person { 
 
    public Woman(String name, int condition) { 
        super(name, condition); 
    } 
 
    public void getPartner(Person person) { 
        if(person instanceof Woman) { 
            System.out.println("汗，我不是同性恋！"); 
        } else { 
            if(this.getCondition() == person.getCondition()) { 
                System.out.println(this.getName() + "和" + person.getName() + "绝配"); 
            } else { 
                System.out.println(this.getName() + "和" + person.getName() + "不相配"); 
            } 
        } 
    } 
 
}
MainClass.java
package com.ibeifeng.ex1; 

public class MainClass { 
    public static void main(String[] args) { 
        Person zhangsan = new Man("张三",5); 
        Person lisi = new Man("李四",6); 
 
        Person xiaofang = new Woman("小芳", 6); 
 
        zhangsan.getPartner(xiaofang); 
        lisi.getPartner(xiaofang); 
        zhangsan.getPartner(lisi); 
 
    } 
}

运用了中介模式的代码：

Person.java
package com.ibeifeng.ex2; 

public abstract class Person { 
    private String name; 
    private int condition; 
    private Mediator mediator; 
 
 
    public Person(String name, int condition, Mediator mediator) { 
        super(); 
        this.name = name; 
        this.condition = condition; 
        this.mediator = mediator; 
    } 
 
    public Mediator getMediator() { 
        return mediator; 
    } 
 
    public void setMediator(Mediator mediator) { 
        this.mediator = mediator; 
    } 
 
    public String getName() { 
        return name; 
    } 
    public void setName(String name) { 
        this.name = name; 
    } 
    public int getCondition() { 
        return condition; 
    } 
 
    public void setCondition(int condition) { 
        this.condition = condition; 
    } 
 
    public abstract void getPartner(Person person); 
 
}
Mediator.java
package com.ibeifeng.ex2; 

public class Mediator { 
    private Man man; 
    private Woman woman; 
 
    public void setMan(Man man) { 
        this.man = man; 
    } 
    public void setWoman(Woman woman) { 
        this.woman = woman; 
    } 
 
    public void getPartner(Person person) { 
        //将搭档设置上 
        if(person instanceof Man) { 
            this.setMan((Man)person); 
        } else { 
            this.setWoman((Woman)person); 
        } 
        //判断条件 
        if(man == null || woman == null) { 
            System.out.println("汗，我不是同性恋!"); 
        } else { 
 
            if(man.getCondition() == woman.getCondition()) { 
                System.out.println(man.getName() + "和" + woman.getName() + "绝配"); 
            } else { 
                System.out.println(man.getName() + "和" + woman.getName() + "不相配"); 
            } 
        } 
    } 
 
}
Man.java
package com.ibeifeng.ex2; 

public class Man extends Person { 
 
    public Man(String name, int condition,Mediator mediator) { 
        super(name, condition, mediator); 
    } 
 
    public void getPartner(Person person) { 
        this.getMediator().setMan(this); 
        this.getMediator().getPartner(person); 
    } 
}
Woman.java
package com.ibeifeng.ex2; 

public class Woman extends Person { 
 
    public Woman(String name, int condition,Mediator mediator) { 
        super(name, condition, mediator); 
    } 
 
    public void getPartner(Person person) { 
        this.getMediator().setWoman(this); 
        this.getMediator().getPartner(person); 
    } 
 
}
MainClass.java
package com.ibeifeng.ex2; 
public class MainClass { 
    public static void main(String[] args) { 
        Mediator mediator = new Mediator(); 
        Person zhangsan = new Man("张三",7,mediator); 
        Person lisi = new Man("李四",7,mediator); 
        Person xiaofang = new Woman("小芳",7,mediator); 
 
        zhangsan.getPartner(lisi); 
 
        xiaofang.getPartner(lisi); 
    } 
}