设计模式学习(十四) 中介者模式
场景:
-- 假如没有总经理,下面3个部门:财务部,市场部,研发部。财务部要发工资,让大家核对公司需要跟市场部和研发部都通气,市场部要接个新项目,需要研发部处理技术,需要财务部出资金.市场部跟各个部门打交道,虽然只有三个部门,但是关系非常乱
-- 实际上,公司都有总经理。各个部门有什么事情都通报到总经理这里,总经理再通知各个相关部门
核心:
-- 如果一个系统中对象之间的联系呈现为网状结构,对象之间之间存在大量的多对多关系,将导致关系及其复杂,这些对象称为“同事对象”;
-- 我们可以引入一个中介者对象,使各个同事对象只跟中介者对象打交道,将复杂的网络结构化解为如下的星状结构
代码:
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package meidiator; //中介者接口 public interface Mediator { void register(String dname,Department d); void command(String dname); }
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package meidiator; //同事类接口 public interface Department { void selfAction(); // 做本部门的事情 void outAction(); // 向总经理发出请求 }
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package meidiator; public class Market implements Department{ private Mediator m;//持有中介者(总经理)的引用 public Market(Mediator m) { super(); this.m = m; m.register("market", this); } @Override public void selfAction() { System.out.println("赶进度"); } @Override public void outAction() { System.out.println("汇报工作,项目进度...而且缺钱了"); m.command("finacial"); } }
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package meidiator; public class Finacial implements Department{ private Mediator m;//持有中介者(总经理)的引用 public Finacial(Mediator m) { super(); 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,钱好多,怎么花"); } }
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package meidiator; public class Development implements Department{ private Mediator m;//持有中介者(总经理)的引用 public Development(Mediator m) { super(); this.m = m; m.register("development", this); } @Override public void selfAction() { System.out.println("专业科研,开发项目"); } @Override public void outAction() { System.out.println("汇报工作,没钱了,需要资金"); } }
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package meidiator; import java.util.HashMap; import java.util.Map; public class President implements Mediator { private Map<String,Department> map= new HashMap<String , Department>(); @Override public void register(String dname, Department d) { map.put(dname,d); } @Override public void command(String dname) { map.get(dname).selfAction(); } }
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package meidiator; public class Client { public static void main(String[] args){ Mediator m = new President(); Market market = new Market(m); Development devp = new Development(m); Finacial f = new Finacial(m); market.selfAction(); market.outAction(); } }
优点:
-- 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