中介者模式

发表于 | 分类于 | 阅读次数:

类图

代码

Colleague

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
abstract class Person{
    private String name;
    private Mediator mediator;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Mediator getMediator() {
        return mediator;
    }

    public void setMediator(Mediator mediator) {
        this.mediator = mediator;
    }

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

ColleagueA

1
2
3
4
5
6
7
8
9
10
11
12
13
14
class HouseOwner extends Person{

    public HouseOwner(String name, Mediator mediator) {
        super(name, mediator);
    }

    public void contact(String message){
        this.getMediator().contact(message, this);
    }

    public void getMessage(String message){
        System.out.println("房主：" + this.getName() + "获得信息:" + message);
    }
}

ColleagueB

1
2
3
4
5
6
7
8
9
10
11
12
13
14
class Tenant extends Person{

    public Tenant(String name, Mediator mediator) {
        super(name, mediator);
    }

    public void contact(String message){
        this.getMediator().contact(message, this);
    }

    public void getMessage(String message){
        System.out.println("租房者：" + this.getName() + "获得信息:" + message);
    }
}

Mediator

1
2
3
abstract class Mediator{
    abstract void contact(String message, Person person);
}

ConcreteMediator

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
class MediatorStructure extends Mediator{

    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
    void contact(String message, Person person) {
        if(person == houseOwner){
            tenant.getMessage(message);
        }else{
            houseOwner.getMessage(message);
        }
    }
}

测试类

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
public class Main {
    public static void main(String args[]){
        //一个房主、一个租房者、一个中介机构
        MediatorStructure mediator = new MediatorStructure();

        //房主和租房者只需要知道中介机构即可
        HouseOwner houseOwner = new HouseOwner("张三", mediator);
        Tenant tenant = new Tenant("李四", mediator);

        //中介结构要知道房主和租房者
        mediator.setHouseOwner(houseOwner);
        mediator.setTenant(tenant);

        tenant.contact("听说你那里有三室的房主出租.....");
        houseOwner.contact("我有房子要出租");
    }
}

运行结果

1
2
房主：张三获得信息:听说你那里有三室的房主出租.....
租房者：李四获得信息:我有房子要出租

总结

优点

适当地使用可以避免同事类之间的耦合

缺点

有些时候同事之间的关系不会复杂到网状结构，所以不要滥用中介者模式，会大幅增加系统的复杂度