23种设计模式-责任链模式

1.责任链模式

为解除请求的发送者和接收者之间耦合，而使多个对象都有机会处理这个请求。将这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它。

优缺点

优点：

请求和处理分开，两者解耦，提供系统的灵活性。

缺点：

性能能问，一个链非常长的时候，非常耗时。因为我们避免建立很长的链。

使用场景

实现方式

请假条：LeaveNode.java

public class LeaveNode {
    /** 请假天数 **/
    private  int number;
    
    /** 请假人 **/
    private String person;
    
    public LeaveNode(String person,int number){
        this.person = person;
        this.number = number;
    }
 
    public int getNumber() {
        return number;
    }
 
    public void setNumber(int number) {
        this.number = number;
    }
 
    public String getPerson() {
        return person;
    }
 
    public void setPerson(String person) {
        this.person = person;
    }
}

抽象处理者：Leader.java

public abstract class Leader {
    /** 姓名 **/
    public String name;
    
    /** 后继者 **/
    protected Leader successor;
    
    public Leader(String name){
        this.name = name;
    }
 
    public void setSuccessor(Leader successor) {
        this.successor = successor;
    }
    
    public abstract void handleRequest(LeaveNode LeaveNode);
}

四个具体处理者：辅导员：Instructor.java

public class Instructor extends Leader{
 
    public Instructor(String name){
        super(name);
    }
    
    public void handleRequest(LeaveNode LeaveNode) {
        if(LeaveNode.getNumber() <= 3){   //小于3天辅导员审批
            System.out.println("辅导员" + name + "审批" +LeaveNode.getPerson() + "同学的请假条,请假天数为" + LeaveNode.getNumber() + "天。");
        }
        else{     //否则传递给系主任
            if(this.successor != null){
                this.successor.handleRequest(LeaveNode);
            }
        }
    }
 
}

系主任： DepartmentHead.java

public class DepartmentHead extends Leader{
 
    public DepartmentHead(String name) {
        super(name);
    }
 
    public void handleRequest(LeaveNode LeaveNode) {
        if(LeaveNode.getNumber() <= 7){   //小于7天系主任审批
            System.out.println("系主任" + name + "审批" +LeaveNode.getPerson() + "同学的请假条,请假天数为" + LeaveNode.getNumber() + "天。");
        }
        else{     //否则传递给院长
            if(this.successor != null){
                this.successor.handleRequest(LeaveNode);
            }
        }
    }
}

院长：Dean.java

public class Dean extends Leader{
 
    public Dean(String name) {
        super(name);
    }
 
    public void handleRequest(LeaveNode LeaveNode) {
        if(LeaveNode.getNumber() <= 10){   //小于10天院长审批
            System.out.println("院长" + name + "审批" +LeaveNode.getPerson() + "同学的请假条,请假天数为" + LeaveNode.getNumber() + "天。");
        }
        else{     //否则传递给校长
            if(this.successor != null){
                this.successor.handleRequest(LeaveNode);
            }
        }
    }
 
}

校长：President.java

public class President extends Leader{
 
    public President(String name) {
        super(name);
    }
 
    public void handleRequest(LeaveNode LeaveNode) {
        if(LeaveNode.getNumber() <= 15){   //小于15天校长长审批
            System.out.println("校长" + name + "审批" +LeaveNode.getPerson() + "同学的请假条,请假天数为" + LeaveNode.getNumber() + "天。");
        }
        else{     //否则不允批准
            System.out.println("请假天天超过15天,不批准...");
        }
    }
 
}

测试类

public class Client {
    public static void main(String[] args) {
        Leader instructor = new Instructor("陈毅");       //辅导员
        Leader departmentHead = new DepartmentHead("王明");    //系主任
        Leader dean = new Dean("张强");      //院长
        Leader president = new President("王晗");     //校长
        
        instructor.setSuccessor(departmentHead);       //辅导员的后续者是系主任
        departmentHead.setSuccessor(dean);             //系主任的后续者是院长
        dean.setSuccessor(president);                  //院长的后续者是校长
        
        //请假3天的请假条
        LeaveNode leaveNode1 = new LeaveNode("张三", 3);
        instructor.handleRequest(leaveNode1);     
        
        //请假9天的请假条
        LeaveNode leaveNode2 = new LeaveNode("李四", 9);
        instructor.handleRequest(leaveNode2);
        
        //请假15天的请假条
        LeaveNode leaveNode3 = new LeaveNode("王五", 15);
        instructor.handleRequest(leaveNode3);
        
        //请假20天的请假条
        LeaveNode leaveNode4 = new LeaveNode("赵六", 20);
        instructor.handleRequest(leaveNode4);
    }
}

参考博客：https://blog.csdn.net/a745233700/article/details/83691491