16、中介者模式

【例】租房
现在租房基本都是通过房屋中介，房主将房屋托管给房屋中介，而租房者从房屋中介获取房屋信息。房屋中介充当租房者与房屋所有者之间的中介者。
类图如下：

//抽象中介者类
public abstract class Mediator {
    public abstract void constact(String message,Person person);
}

//抽象同事类
public abstract class Person {
    protected String name;
    protected Mediator mediator;

    public Person(String name, Mediator mediator) {
        this.name = name;
        this.mediator = mediator;
    }
}

//具体的同事角色类1 房主
public class HouseOwner extends Person {
    public HouseOwner(String name, Mediator mediator) {
        super(name, mediator);
    }
    //和中介联系（沟通）
    public void constact(String message) {
        mediator.constact(message,this);
    }
    //获取信息
    public void getMessage(String message) {
        System.out.println("房主"+name+"获得的信息是："+message);
    }
}

//具体的同事角色类-租客
public class Tenant extends Person{
    public Tenant(String name, Mediator mediator) {
        super(name, mediator);
    }
    //和中介联系（沟通）
    public void constact(String message) {
        mediator.constact(message,this);
    }

    //获取信息
    public void getMessage(String message) {
        System.out.println("租房者" + name + "获取到的信息是：" + message);
    }
}

//具体的中介者角色类
public class MediatorImpl extends Mediator{
    //聚合房主和租房者对象
    private HouseOwner houseOwner;
    private Tenant tenant;

    public HouseOwner getHouseOwner() {
        return houseOwner;
    }

    public void setHouseOwner(HouseOwner houseOwner) {
        this.houseOwner = houseOwner;
    }

    public Tenant getTenant() {
        return tenant;
    }

    public void setTenant(Tenant tenant) {
        this.tenant = tenant;
    }

    @Override
    public void constact(String message, Person person) {
        if (person==houseOwner){
            tenant.getMessage(message);
        }else {
            houseOwner.getMessage(message);
        }
    }
}

public class Client {
    public static void main(String[] args) {
        //创建中介者对象
        MediatorImpl mediator=new MediatorImpl();
        //创建租房者对象
        Tenant tenant=new Tenant("李四",mediator);
        //创建房主对象
        HouseOwner houseOwner=new HouseOwner("包租婆",mediator);
        //中介者要知道具体的房主和租房者
        mediator.setTenant(tenant);
        mediator.setHouseOwner(houseOwner);

        tenant.constact("我要租房!");
        houseOwner.constact("我这里有房子，你要租吗");
    }
}