java設計模式之責任鏈模式

①UML設計：

②定義：職責鏈模式（稱責任鏈模式）將請求的處理對象像一條長鏈一般組合起來，形成一條對象鏈。請求並不知道具體執行請求的對象是哪一個，這樣就實現了請求與處理對象之間的解耦

③示例：

public abstract class Leader {
    private Leader nextLeader;

    public abstract void deal(Vocation vocation);

    public void setNextLeader(Leader leader) {
        this.nextLeader = leader;
    }

    public Leader getNextLeader() {
        return nextLeader;
    }
}

/**
 * 1天的假期由小組長審批
 */
public class GroupLeader extends Leader {

    private final int day = 1;

    @Override
    public void deal(Vocation vocation) {
        if (vocation.getDays() > day) {
            getNextLeader().deal(vocation);
        } else {
            System.out.println("GroupLeader deal the vocation for 1 day");
        }
    }
}

/**
 * 1~3天的假期有部門領導審批
 */
public class DepartmentLeader extends Leader {

    private final int days = 3;

    @Override
    public void deal(Vocation vocation) {
        if (vocation.getDays() > days) {
            getNextLeader().deal(vocation);
        } else {
            System.out.println("Department deal the vocation for more than 1-3 days");
        }
    }
}

/**
 * 3天以上的假期由主管審批
 */
public class GeneralLeader extends Leader {
    @Override
    public void deal(Vocation vocation) {
        System.out.println("GeneralLeader deal the vocation no matter how many days");
    }
}

public class Vocation {
    private int    days;

    private String reasons;

    public void setDays(int days) {
        this.days = days;
    }

    public int getDays() {
        return days;
    }

    public void setReasons(String reasons) {
        this.reasons = reasons;
    }

    public String getReasons() {
        return reasons;
    }
}

public class Client3 {
    public static void main(String[] args) {
        Vocation vocation = new Vocation();
        vocation.setDays(4);//設置不同的請假天數，不同的領導人會處理
        Leader gpLeader = new GroupLeader();
        Leader dmLeader = new DepartmentLeader();
        Leader gLeader = new GeneralLeader();
        gpLeader.setNextLeader(dmLeader);
        dmLeader.setNextLeader(gLeader);
        gpLeader.deal(vocation);//首先小組長先處理請求
    }
}