行為型模式又可以分成以下四類：第一類：通過父類與子類的關係進行實現。第二類：兩個類之間。第三類：類的狀態。第四類：通過中間類

　　命令模式屬於第四類，通過中間類

　　我們來看一下兩個類之間是如何通過中間類來相互影響的

package behavior.pattern.intermediator.mediator;

public abstract class AbstractColleague {
    protected float number;  
      
    public float getNumber() {  
        return number;  
    }  
  
    
 
public void setNumber(float number){  
        this.number = number;  
    }  
    //注意這裡的引數不再是同事類，而是一箇中介者  
    public abstract void setNumber(float number, AbstractMediator am); 
}

package behavior.pattern.intermediator.mediator;

public class ColleagueA extends AbstractColleague {
    public void
 
 setNumber(float number, AbstractMediator am) {  
        this.number = number;  
        am.AaffectB();  
    }
}

package behavior.pattern.intermediator.mediator;

public class ColleagueB extends AbstractColleague {
    @Override  
    public void setNumber(float number, AbstractMediator am) {  
        
 
this.number = number;  
        am.BaffectA();  
    }
}

package behavior.pattern.intermediator.mediator;

public abstract class AbstractMediator {
    protected AbstractColleague A;  
    protected AbstractColleague B;  
      
    public AbstractMediator(AbstractColleague a, AbstractColleague b) {  
        A = a;  
        B = b;  
    }  
  
    public abstract void AaffectB();  
      
    public abstract void BaffectA();
}

package behavior.pattern.intermediator.mediator;

import org.apache.commons.math3.util.Precision;

public class Mediator extends AbstractMediator {

    public Mediator(AbstractColleague a, AbstractColleague b) {  
        super(a, b);  
    }  
  
    //處理A對B的影響  
    public void AaffectB() {  
        float number = A.getNumber();  
        B.setNumber(number*10);  
    }  
  
    //處理B對A的影響  
    public void BaffectA() {  
        float number = B.getNumber();
        A.setNumber(Precision.round(number/10, getDecimalDigit(number) + 1));  
    }
    
    private int getDecimalDigit(float number)
    {
        int digit = 0;
        String numberString = String.valueOf(number);
        if(numberString.indexOf(".") != -1)
        {
            digit = numberString.substring(numberString.indexOf(".") + 1).length();
        }
        else
        {
            digit = 0;
        }
        return digit;
    }
}

　　測試程式碼

package behavior.pattern.intermediator.mediator;

public class Client {
    public static void main(String[] args){  
        AbstractColleague collA = new ColleagueA();  
        AbstractColleague collB = new ColleagueB();  
          
        AbstractMediator am = new Mediator(collA, collB);  
          
        System.out.println("==========通過設定A影響B==========");  
        collA.setNumber(1001, am);  
        System.out.println("collA的number值為："+collA.getNumber());  
        System.out.println("collB的number值為A的10倍："+collB.getNumber());  
        
        System.out.println("==========通過設定B影響A==========");  
        collB.setNumber(10.02F, am);  
        System.out.println("collB的number值為："+collB.getNumber());  
        System.out.println("collA的number值為B的0.1倍："+collA.getNumber());  
          
    }
}

　　執行結果