把请求从链中的一个对象传到下一个对象，直到请求被响应为止。通过这种方式去除对象之间的耦合。

package com.strife.pattern.chain;

/**
 * 职责链模式
 *
 * @author mengzhenghao
 * @date 2022/6/6
 */
public class ChainCode {

    public static void main(String[] args) {
        AbstractAuditHandler projectHandler = new ProjectManger();
        AbstractAuditHandler deptHandler = new DeptManger();
        AbstractAuditHandler ceoHandler = new CeoManger();

        projectHandler.setSuccessor(deptHandler);
        deptHandler.setSuccessor(ceoHandler);

        projectHandler.handleLeaveDay("zhangsan", 7);
    }
}

abstract class AbstractAuditHandler {

    /** 只有下一个处理请求的对象 */
    protected AbstractAuditHandler successor = null;

    public AbstractAuditHandler getSuccessor() {
        return successor;
    }
    public void setSuccessor(AbstractAuditHandler successor) {
        this.successor = successor;
    }
    /** 请假天数审批 */
    public abstract void handleLeaveDay (String user,Integer day);
}

/** 项目经理审批 */
class ProjectManger extends AbstractAuditHandler {

    @Override
    public void handleLeaveDay(String user, Integer day) {
        if (day <= 3){
            System.out.println("项目经理审批：同意【"+user+"】,请假【"+day+"】天");
        } else {
            System.out.println("项目经理无权审批");
            if (getSuccessor() != null){
                getSuccessor().handleLeaveDay(user,day);
            }
        }
    }
}

/**部门经理审批 */
class DeptManger extends AbstractAuditHandler{

    @Override
    public void handleLeaveDay(String user, Integer day) {
        if (day > 3 && day <= 5){
            System.out.println("部门经理审批：同意【"+user+"】,请假【"+day+"】天");
        } else {
            System.out.println("部门经理无权审批");
            if (getSuccessor() != null){
                getSuccessor().handleLeaveDay(user,day);
            }
        }
    }
}

/** CEO审批 */
class CeoManger extends AbstractAuditHandler{
    @Override
    public void handleLeaveDay(String user, Integer day) {
        if (day > 5){
            System.out.println("CEO审批：同意【"+user+"】,请假【"+day+"】天");
        } else {
            if (getSuccessor() != null){
                getSuccessor().handleLeaveDay(user,day);
            }
        }
    }
}