设计模式 - 中间人模式

Posted 2021-04-25 IT之心

类别

行为型

意图

定义一个对象，用来封装一组对象交互。
中介者通过保持其他对象的引用来促进松耦合，
它可以让你独立地改变他们的互动。

适用范围

• 一组对象以明确定义但复杂的方式进行通信。所产生的相互依赖关系是非结构化的，难以理解

• 重复使用对象是困难的，因为它涉及并与许多其他对象进行通信

• 分布在几个类之间的行为应该可以自定义，而不需要很多的子类化

主要代码

public interface Party {

    void addMember(PartyMember member);

    void act(PartyMember actor, Action action);

}

public interface PartyMember {

    void joinedParty(Party party);

    void partyAction(Action action);

    void act(Action action);

}

public abstract class PartyMemberBase implements PartyMember {

    private static final Logger LOGGER = LoggerFactory.getLogger(PartyMemberBase.class);

    protected Party party;

    @Override
    public void joinedParty(Party party) {
        LOGGER.info("{} joins the party", this);
        this.party = party;
    }

    @Override
    public void partyAction(Action action) {
        LOGGER.info("{} {}", this, action.getDescription());
    }

    @Override
    public void act(Action action) {
        if (party != null) {
            LOGGER.info("{} {}", this, action);
            party.act(this, action);
        }
    }

    @Override
    public abstract String toString();
}

public class Hobbit extends PartyMemberBase {

    @Override
    public String toString() {
        return "Hobbit";
    }
}

Party party = new PartyImpl();
        Hobbit hobbit = new Hobbit();
        Wizard wizard = new Wizard();
        Rogue rogue = new Rogue();
        Hunter hunter = new Hunter();

        // add party members
        party.addMember(hobbit);
        party.addMember(wizard);
        party.addMember(rogue);
        party.addMember(hunter);

        // perform actions -> the other party members
        // are notified by the party
        hobbit.act(Action.ENEMY);
        wizard.act(Action.TALE);
        rogue.act(Action.GOLD);
        hunter.act(Action.HUNT);

引用

• Design patterns implemented in Java

• Class Timer

• Interface Executor

• Interface ExecutorService

• Interface ScheduledExecutorService

• Class Method