设计模式之访问者模式

访问者模式

访问者模式结构图：

示例代码：

// 抽象访问者
public interface Visistor {

    void checkWork(Engineer engineer);

    void checkWork(Manager manager);
}

// 具体访问者boss
public class BossVisistor implements Visistor{
    @Override
    public void checkWork(Engineer engineer) {
        engineer.workProgress();
    }

    @Override
    public void checkWork(Manager manager) {
        manager.workProgress();
    }
}

// 具体访问者投资人
public class InvestorsVisistor implements Visistor{
    @Override
    public void checkWork(Engineer engineer) {
        engineer.workProgress();
    }

    @Override
    public void checkWork(Manager manager) {
        manager.workProgress();
    }
}


// 抽象工作者（假定员工只有工程师和项目经理）
public abstract class Worker {
    protected String name;
    abstract void accept(Visistor visistor);
}

// 具体工作者工程师
public class Engineer extends Worker{

    public Engineer(String name) {
        this.name = name;
    }

    @Override
    void accept(Visistor visistor) {
        visistor.checkWork(this);
    }

    public void workProgress(){
        System.out.println(this.getClass().getSimpleName() + name + "完成工作进度：" + new Random().nextInt(100) + "%");
    }
}

// 具体工作者项目经理
public class Manager extends Worker{

    public Manager(String name) {
        this.name = name;
    }

    @Override
    void accept(Visistor visistor) {
        visistor.checkWork(this);
    }

    public void workProgress(){
        System.out.println(this.getClass().getSimpleName() + name + "完成产品设计进度：" + new Random().nextInt(100) + "%");
    }
}

// 容器
public class ObjectStruct {
    List<Worker> list = new ArrayList<>();

    public void accept(Visistor visistor){
        list.forEach(a -> a.accept(visistor));
    }

    public void add(Worker worker){
        list.add(worker);
    }

    public void remove(Worker worker){
        list.remove(worker);
    }
}

//　测试
public class VisistorTest {

    public static void main(String[] args) {
        ObjectStruct objectStruct = new ObjectStruct();
        objectStruct.add(new Engineer("张三"));
        objectStruct.add(new Engineer("李四"));
        objectStruct.add(new Engineer("王五"));
        objectStruct.add(new Manager("斯蒂芬"));
        objectStruct.add(new Manager("詹姆斯"));
        objectStruct.add(new Manager("约翰逊"));

        System.out.println("=========老板检查工作进度＝＝＝＝＝＝＝＝＝＝＝");
        objectStruct.accept(new BossVisistor());
        System.out.println("=========投资人检查工作进度＝＝＝＝＝＝＝＝＝＝＝");
        objectStruct.accept(new InvestorsVisistor());
    }
}