策略设计模式用例在高校Intranet系统开发中的应用

Question

我可以使用策略模式来实现以下逻辑:因此，假设学费是根据学生的整体表现来计算的，例如，如果学生的总体平均分数超过70分，他的学费将减少70%。以此类推..如果平均分数低于50%，其他情况下则不打折。因此，有不同的策略来计算折扣，这取决于平均分数。如何在Java代码中实现这一点？我认为学生类将有计算平均分数的方法，接口TuitionFeeCalculator和三个策略:70%折扣，50%折扣和noDiscount实现TuitionFeeCalculator。

Answer 1

假设这只是一个课堂练习，因为您永远不会为这么简单的事情实现策略模式，但您正在寻找的内容如下：

public interface TuitionFeeCalculator {
    double calculateFee(double fee);
}

public class Fee70 implements TuitionFeeCalculator {
    @Override
    public double calculateFee(double fee) {
        return fee * (1-0.7);
    }
}

public class Fee50 implements TuitionFeeCalculator {
    @Override
    public double calculateFee(double fee) {
        return fee * (1-0.5);
    }
}

public class FeeNoDiscount implements TuitionFeeCalculator {
    @Override
    public double calculateFee(double fee) {
        return fee;
    }
}

public class Student {
    double tf;

    public Student(double tuitionFee) {
        this.tf = tuitionFee;
    }
}

public static void main(String[] args) {

    double averageMark = 90;
    double fee = 10000;

    TuitionFeeCalculator feeCalculator;
    if(averageMark >70) {
        feeCalculator = new Fee70();
    } else if (averageMark > 50) {
        feeCalculator = new Fee50();
    } else {
        feeCalculator = new FeeNoDiscount();
    }

    Student s = new Student(feeCalculator.calculateFee(fee));
}

Answer 2

有没有人能检查一下这个代码，告诉我有没有什么问题

 public class StrategyDemo
 {

  public static void main(String[] args)
  {
    Student s = new Student();
    TuitionFee fee = new TuitionFee();
    fee.setTuitionFee(5000);
    StudentStatus status = new StudentStatus(s);
    CalculatorSelectorFactory calc = new CalculatorSelectorFactory(status.getStatus());
    TuitionFeeCalculator tfc = calc.getCalculator();
    double newFee = tfc.calculate();



  }
}


public class StudentStatus
{
  private Student student;

  public StudentStatus(Student student){
    this.student = student;
  }
  public List<Module> getAllModules(){
        //query the database and get all modules a particular student is enrolled for
        return modules; //return list of modules
  }
  public int getStatus(){
    int total = 0;
    int count = 0;
    for(Module m: getAllModules()){
        total += m.getMark();
        count++;
    }
    int average = total/count;
    return average;
  }
}
public class TuitionFee{
    private double tuitionFee;

    public void setTuitionFee(double tuitionFee){
        this.tuitionFee = tuitionFee;
    }
    public double getTuitionFee(){
        return tuitionFee;
    }
}
public interface TuitionFeeCalculator{
    public double calculate();
}
public class Discount70 implements TuitionFeeCalculator{
    @Override
    public double calculate(TuitionFee tuitionFee){
        double discount = tuitionFee * 0.7; //70% discount
        return tuitionFee-discount;
    }
}
public class Discount50 implements TuitionFeeCalculator{
    @Override
    public double calculate(TuitionFee tuitionFee){
        double discount = tuitionFee * 0.5; //50% discount
        return tuitionFee-discount;
    }
}
public class NoDiscount implements TuitionFeeCalculator{
    @Override
    public double calculate(TuitionFee tuitionFee){
        return tuitionFee; //no discount
    }
}

public class CalculatorSelectorFactory{
    TuitionFeeCalculator tfc;
    public CalculatorSelectorFactory(int status){
        if(status>=70){
          tfc=new Discount70();
        }
        else if(status>=50){
          tfc = new Discount50();
        }
        else{
          tfc = new NoDiscount();
        }       
    }
    public TuitionFeeCalculator getCalculator(){
        return tfc;
    }
}