GOF23设计模式之 中介者模式Mediator

核心

• 如果一个系统中对象之间的联系呈现为网状结构，对象之间存在大量多对多的关系，将熬制关系及其复杂，这些对象称之为 “同事对象”
• 我们可以阴雨一个中介者对象，使各个同事对象只跟中介者打交道，将复杂的网络结构化解为星形结构。

中介者模式类图

中介者模式的本质

• 解耦多个同事对象之间的交互关系。每个对象都持有中介者对象的引用，只跟中介者对象打交道。我们通过中介者对象统一管理这些交互关系

开发当中常见的场景

• MVC模式（其中的C，控制器就是一个中介者对象。M和V都和他打交道）
• 窗口游戏程序，窗口软件开发中窗口对象也是一个中介者对象
• 图形界面开发GUI中，多个组件之间的交互，可以通过引入一个中介者对象来解决，可以使整体的窗口对象或者DOM对象
  -Java.lang.reflect.Method#invoke()

一种实现

• Mediator

package com.coderbean.mediator;/** * Created by Chang on 15/10/3. */public interface Mediator {    void register(String dname, Department d);    void command(String name);}

• President

package com.coderbean.mediator;import java.util.HashMap;import java.util.Map;/** * Created by Chang on 15/10/3. */public class President implements Mediator {    private Map<String,Department> map = new HashMap<String, Department>();    @Override    public void register(String dname, Department d) {        this.map.put(dname,d);    }    @Override    public void command(String name) {        map.get(name).selfAction();    }}

• Department

package com.coderbean.mediator;/** * 同事类接口 * Created by Chang on 15/10/3. */public interface Department {    void selfAction();  //做本部门的事情    void outAction();   //向总经理发出申请}

• Finacial

package com.coderbean.mediator;/** * Created by Chang on 15/10/3. */public class Finacial implements Department {    private Mediator m;    public Finacial(Mediator m) {        this.m = m;        m.register("Finacial", this);    }    @Override    public void selfAction() {        System.out.println("数钱");    }    @Override    public void outAction() {        System.out.println("汇报工作,钱太多了,不知道怎么花?");    }}

• Market

package com.coderbean.mediator;/** * Created by Chang on 15/10/3. */public class Market implements Department {    private Mediator m;    public Market(Mediator m) {        this.m = m;        m.register("Market", this);    }    @Override    public void selfAction() {        System.out.println("跑去接项目");    }    @Override    public void outAction() {        System.out.println("汇报工作,项目承接的进度,需要资金支持");        m.command("Finacial");    }}

• Development

package com.coderbean.mediator;/** * Created by Chang on 15/10/3. */public class Development implements Department {    private Mediator m;    public Development(Mediator m) {        this.m = m;        m.register("Development", this);    }    @Override    public void selfAction() {        System.out.println("专心科研,做研发");    }    @Override    public void outAction() {        System.out.println("汇报工作,没钱了");    }}

• Client

package com.coderbean.mediator;/** * Created by Chang on 15/10/3. */public class Client {    public static void main(String[] args) {        Mediator mediator = new President();        Department market = new Market(mediator);        Department department = new Development(mediator);        Department Finacial = new Finacial(mediator);        market.selfAction();        market.outAction();    }}