二十三种设计模式全面解析-职责链模式（Chain of Responsibility Pattern）：解放代码责任链，提升灵活性与可维护性

// 抽象处理者
abstract class Approver {
    protected Approver nextApprover;
    public void setNextApprover(Approver nextApprover) {
        this.nextApprover = nextApprover;
    }
    public abstract void approveRequest(double amount);
}
// 具体处理者
class Manager extends Approver {
    public void approveRequest(double amount) {
        if (amount <= 1000) {
            System.out.println("Manager approved the purchase request.");
        } else if (nextApprover != null) {
            nextApprover.approveRequest(amount);
        }
    }
}
class Director extends Approver {
    public void approveRequest(double amount) {
        if (amount <= 5000) {
            System.out.println("Director approved the purchase request.");
        } else if (nextApprover != null) {
            nextApprover.approveRequest(amount);
        }
    }
}
class CEO extends Approver {
    public void approveRequest(double amount) {
        if (amount <= 10000) {
            System.out.println("CEO approved the purchase request.");
        } else {
            System.out.println("The purchase request exceeds the company's limit.");
        }
    }
}
// 客户端代码
public class Client {
    public static void main(String[] args) {
        Approver manager = new Manager();
        Approver director = new Director();
        Approver ceo = new CEO();
        manager.setNextApprover(director);
        director.setNextApprover(ceo);
        manager.approveRequest(500);
        manager.approveRequest(5000);
        manager.approveRequest(15000);
    }
}