责任链模式

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import java.util.Random;import com.imooc.pattern.cor.handler.PriceHandler;import com.imooc.pattern.cor.handler.PriceHandlerFactory;/* * 客户，请求折扣，一级级申请折扣 * 实际案例如：异常处理机制，dom事件，http filter等 */public class Customer {    private PriceHandler priceHandler;    public void setPriceHandler(PriceHandler priceHandler) {        this.priceHandler = priceHandler;    }    public void requestDiscount(float discount){        priceHandler.processDiscount(discount);    }    public static void main(String[] args){        Customer customer = new Customer();        customer.setPriceHandler(PriceHandlerFactory.createPriceHandler());        Random rand = new Random();        for(int i=1;i<=100;i++){            System.out.print(i+":");            customer.requestDiscount(rand.nextFloat());        }    }}

/* * 价格处理人，负责处理客户折扣申请 */public abstract class PriceHandler {    /*     * 直接后继，用于传递请求     */    protected PriceHandler successor;    public void setSuccessor(PriceHandler successor) {        this.successor = successor;    }    /*     * 处理折扣申请     */    public abstract  void processDiscount(float discount);}

public class PriceHandlerFactory {    /*     * 创建PriceHandler的工厂方法     */    public static PriceHandler createPriceHandler() {        PriceHandler sales = new Sales();        PriceHandler lead = new Lead();        PriceHandler man = new Manager();        PriceHandler dir = new Director();        PriceHandler vp = new VicePresident();        PriceHandler ceo = new CEO();        sales.setSuccessor(lead);        lead.setSuccessor(man);        man.setSuccessor(dir);        dir.setSuccessor(vp);        vp.setSuccessor(ceo);        return sales;    }}

/* * 销售， 可以批准5%以内的折扣 */public class Sales extends PriceHandler {    @Override    public void processDiscount(float discount) {        if(discount <= 0.05){            System.out.format("%s批准了折扣：%.2f%n", this.getClass().getName(), discount);        }else{            //自己没权限处理就传递到上一级处理，形成责任链            successor.processDiscount(discount);        }    }}

/* * CEO， 可以批准55%以内的折扣 * 折扣超出55%， 就拒绝申请 */public class CEO extends PriceHandler {    @Override    public void processDiscount(float discount) {        if(discount<=0.55){            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);        }    }}

参考：http://www.imooc.com/

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