责任链模式

责任链模式
传统做法就是使用if else

//请求类
public class PurchaseRequest {

    private int type = 0; //请求类型
    private float price = 0.0f; //请求金额
    private int id = 0;
    //构造器
    public PurchaseRequest(int type, float price, int id) {
        this.type = type;
        this.price = price;
        this.id = id;
    }
    public int getType() {
        return type;
    }
    public float getPrice() {
        return price;
    }
    public int getId() {
        return id;
    }
}
//处理类
public abstract class Approver {
    Approver approver;  //下一个处理者
    String name; // 当前处理人的名字
    
    public Approver(String name) {
        this.name = name;
    }

    //下一个处理者
    public void setApprover(Approver approver) {
        this.approver = approver;
    }
    
    //处理审批请求的方法，得到一个请求, 处理是子类完成，因此该方法做成抽象
    public abstract void processRequest(PurchaseRequest purchaseRequest);
}

//处理类实现
public class DepartmentApprover extends Approver {
    public DepartmentApprover(String name) {
        super(name);
    }
    
    @Override
    public void processRequest(PurchaseRequest purchaseRequest) {
        if(purchaseRequest.getPrice() <= 5000) {
            System.out.println(" 请求编号 id= " + purchaseRequest.getId() + " 被 " + this.name + " 处理");
        }else {
            approver.processRequest(purchaseRequest);
        }
    }
}
public class CollegeApprover extends Approver {

    public CollegeApprover(String name) {
        super(name);
    }
    
    @Override
    public void processRequest(PurchaseRequest purchaseRequest) {
        if(purchaseRequest.getPrice() < 5000 && purchaseRequest.getPrice() <= 10000) {
            System.out.println(" 请求编号 id= " + purchaseRequest.getId() + " 被 " + this.name + " 处理");
        }else {
            approver.processRequest(purchaseRequest);
        }
    }
}
public class ViceSchoolMasterApprover extends Approver {

    public ViceSchoolMasterApprover(String name) {
        super(name);
    }
    
    @Override
    public void processRequest(PurchaseRequest purchaseRequest) {
        if(purchaseRequest.getPrice() < 10000 && purchaseRequest.getPrice() <= 30000) {
            System.out.println(" 请求编号 id= " + purchaseRequest.getId() + " 被 " + this.name + " 处理");
        }else {
            approver.processRequest(purchaseRequest);
        }
    }
}
public class SchoolMasterApprover extends Approver {

    public SchoolMasterApprover(String name) {
        super(name);
    }
    
    @Override
    public void processRequest(PurchaseRequest purchaseRequest) {
        if(purchaseRequest.getPrice() > 30000) {
            System.out.println(" 请求编号 id= " + purchaseRequest.getId() + " 被 " + this.name + " 处理");
        }else {
            approver.processRequest(purchaseRequest);
        }
    }
}


public class Client {

    public static void main(String[] args) {
        PurchaseRequest purchaseRequest = new PurchaseRequest(1, 31000, 1);
        
        //创建相关的审批人
        DepartmentApprover departmentApprover = new DepartmentApprover("张主任");
        CollegeApprover collegeApprover = new CollegeApprover("李院长");
        ViceSchoolMasterApprover viceSchoolMasterApprover = new ViceSchoolMasterApprover("王副校");
        SchoolMasterApprover schoolMasterApprover = new SchoolMasterApprover("佟校长");
    
        //需要将各个审批级别的下一个设置好 (处理人构成环形: )  这里就是生成处理链条 感觉还不如if else 直接
        departmentApprover.setApprover(collegeApprover);
        collegeApprover.setApprover(viceSchoolMasterApprover);
        viceSchoolMasterApprover.setApprover(schoolMasterApprover);
        schoolMasterApprover.setApprover(departmentApprover);
        
        departmentApprover.processRequest(purchaseRequest);
        viceSchoolMasterApprover.processRequest(purchaseRequest);
    }
}