java设计模式(五)责任链模式
很多对象有每个对象对其下家的引用而连接起来形成一条链,请求在这条链上传递,直到链上某个对象决定处理此请求,应用场景如单位审批流程等。
要点:1)抽象处理者角色:定义处理请求接口及设定下家引用
2)具体处理着角色:具体处理请求或选择将请求传给下家
1、抽象处理者角色类,定义处理请求接口及下家引用
public abstract class PriceHandle { protected PriceHandle successor; public void setSuccessor(PriceHandle successor) { this.successor = successor; } public abstract void process(float discount); public static PriceHandle createPriceHandle() { PriceHandle sales = new Sales(); PriceHandle direct = new Direct(); PriceHandle ceo = new CEO(); sales.setSuccessor(direct); direct.setSuccessor(ceo); return sales; } }
2、具体处理者角色类销售类
public class Sales extends PriceHandle { public void process(float discount) { if(discount <= 0.1) { System.out.format("%s批准了折扣:%.2f%n",this.getClass().getName(), discount); } else { successor.process(discount); } } }
3、具体处理者角色主管类
public class Direct extends PriceHandle { public void process(float discount) { if(discount <= 0.2) { System.out.format("%s批准了折扣:%.2f%n",this.getClass().getName(), discount); } else { successor.process(discount); } } }
4、具体处理者角色ceo类
public class CEO extends PriceHandle { public void process(float discount) { if(discount <= 0.3) { System.out.format("%s批准了折扣:%.2f%n",this.getClass().getName(), discount); } else { System.out.format("%s拒绝了折扣:%.2f%n",this.getClass().getName(), discount); } } }
5、测试类
public class Model { private PriceHandle priceHandle; public void setPriceHandle(PriceHandle priceHandle) { this.priceHandle = priceHandle; } public void requestDiscount(float discount) { priceHandle.process(discount); } public static void main(String[] args) { Model customer = new Model(); customer.setPriceHandle(PriceHandle.createPriceHandle()); Random random = new Random(); for(int i = 0; i < 100; i++) { System.out.print(i + ":"); customer.requestDiscount(random.nextFloat()); } } }