多层If语句 和 表格驱动 的对比

网文提到表格驱动,总喜欢拿一层if做例子,然而这样未免也太简单.

下文是三层缩进的if和表驱动比较,大家可自行判断优劣.

业务是这样的,某景点分旺季票价和淡季票价,淡季票为旺季的一半,15岁以下孩子再减半,60岁以上老人再三三折,成人中有军官证的再打二五折,有士兵证的打两折.(假定非实际业务,勿对号入座)

代码:

package tabledriven;

/**
 *   门票计价器
 * 传统方式和表格驱动比较
 *
 */
public class TicketCalculater {
    // Price
    private double price=144;
    
    // discout array
    private int[][][] arr= {
                                {
                                    {2*4,2*5,2*1},
                                    {2*2,2*2,2*2},
                                    {2*3,2*3,2*3},
                                },
                                {
                                    {1*4,1*5,1*1},
                                    {1*2,1*2,1*2},
                                    {1*3,1*3,1*3},
                                },
                           };
    
    // Traditional
    public double getPriceTraditional(int month,Person person) {
        double discount=1;
        
        if(6<month && month<11) {
            discount*=1;
            
            if(person.getAge()<15) {
                discount*=0.5;
            }else if(person.getAge()>60) {
                discount*=0.33333333333333;
            }else {
                if(person.isOfficer()) {
                    discount*=0.25;
                }else if(person.isSoldier()) {
                    discount*=0.20;
                }
            }
        }else {
            discount*=0.5;
            
            if(person.getAge()<15) {
                discount*=0.5;
            }else if(person.getAge()>60) {
                discount*=0.333333333333333;
            }else {
                if(person.isOfficer()) {
                    discount*=0.25;
                }else if(person.isSoldier()) {
                    discount*=0.20;
                }
            }
        }
        
        return price*discount;
    }
    
    // Table driven
    public double getPriceTableDriven(int month,Person person) {
        double discount=1;
        
        int index1,index2,index3;
        
        if(6<month && month<11) {
            index1=1;
        }else {
            index1=0;
        }
        
        if(person.getAge()<15) {
            index2=1;
        }else if(person.getAge()>60) {
            index2=2;
        }else {
            index2=0;
        }
        
        if(person.isOfficer()) {
            index3=0;
        }else if(person.isSoldier()) {
            index3=1;
        }else {
            index3=2;
        }
        
        discount=arr[index1][index2][index3];
        
        return price/discount;
    }
    
    // Entry point
    public static void main(String[] args) {
        TicketCalculater tc=new TicketCalculater();
        
        Person p1=new Person(30,false,false);
        System.out.println("Ticket price="+round2DecimalPlaces(tc.getPriceTraditional(2, p1)));
        System.out.println("Ticket price(Table)="+round2DecimalPlaces(tc.getPriceTableDriven(2, p1)));
        
        Person p2=new Person(14,false,false);
        System.out.println("Ticket price="+round2DecimalPlaces(tc.getPriceTraditional(5, p2)));
        System.out.println("Ticket price(Table)="+round2DecimalPlaces(tc.getPriceTableDriven(5, p2)));
        
        Person p3=new Person(44,true,false);
        System.out.println("Ticket price="+round2DecimalPlaces(tc.getPriceTraditional(8, p3)));
        System.out.println("Ticket price(Table)="+round2DecimalPlaces(tc.getPriceTableDriven(8, p3)));
        
        Person p4=new Person(68,false,true);
        System.out.println("Ticket price="+round2DecimalPlaces(tc.getPriceTraditional(11, p4)));
        System.out.println("Ticket price(Table)="+round2DecimalPlaces(tc.getPriceTableDriven(11, p4)));
    }
    
    // round two decimal places of a double
    public static String round2DecimalPlaces(double d){
        java.text.DecimalFormat df =new java.text.DecimalFormat("#0.00");  
        return df.format(d);
    }
}

Person类:

package tabledriven;

public class Person {
    private int age;
    private boolean isOfficer;
    private boolean isSoldier;
    
    public Person(int age,boolean isOfficer,boolean isSoldier) {
        this.age=age;
        this.isOfficer=isOfficer;
        this.isSoldier=isSoldier;
    }
    
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public boolean isOfficer() {
        return isOfficer;
    }
    public void setOfficer(boolean isOfficer) {
        this.isOfficer = isOfficer;
    }
    public boolean isSoldier() {
        return isSoldier;
    }
    public void setSoldier(boolean isSoldier) {
        this.isSoldier = isSoldier;
    }
}

运行结果:

Ticket price=72.00
Ticket price(Table)=72.00
Ticket price=36.00
Ticket price(Table)=36.00
Ticket price=36.00
Ticket price(Table)=36.00
Ticket price=24.00
Ticket price(Table)=24.00

--END-- 2019-12-11 14:01