编程题 某公司的雇员分为5类，每类员工都有相应的封装类，这5个类的信息如下所示。 (1) Employee： 这是所有员工总的父类。 ①属性：员工的姓名,员工的生日月份 ②方法：getSalary (int month) 根据参数月份来确定工资，如果该月员工过生日，则公司会额外奖历100 元。 ② SalariedEmployee： Employee 的子类，拿固定工资的员工。 ①属性：月薪。 (3)HourlyEmployee： Employee 的子类，按小时拿工资的员工，每月工作超出160小时的部分按照1.5倍工资发放。 ①属性：每小时的工资、每月工作的小时数。 (④) SalesEmployee： Employee 的子类，销售，王资由月销售额和提成率诀定。 ①属性：月销售额、提成率。 (5) BasePlus SalesEmployee: SalesEmployee 的子类，有固定底新的销售人员，工资由底新加 上销售提成部分。 ①属性：底薪。 本题要求根据上述雇员分类，编写一个程序，实现以下功能： （1）创建一个Employee 数组，分别创建若干不同的Employee对象，并打印某个月的工资。 (2）每个类都完全封装，不允许非私有化属性。

以下是实现上述功能的代码示例：

public class Employee {
    private String name;
    private int birthMonth;

    public Employee(String name, int birthMonth) {
        this.name = name;
        this.birthMonth = birthMonth;
    }

    public String getName() {
        return name;
    }

    public int getBirthMonth() {
        return birthMonth;
    }

    public double getSalary(int month) {
        double salary = 0;
        // 具体实现根据子类的不同而不同，此处略去
        return salary;
    }
}

public class SalariedEmployee extends Employee {
    private double monthlySalary;

    public SalariedEmployee(String name, int birthMonth, double monthlySalary) {
        super(name, birthMonth);
        this.monthlySalary = monthlySalary;
    }

    public double getMonthlySalary() {
        return monthlySalary;
    }

    @Override
    public double getSalary(int month) {
        double salary = monthlySalary;
        if (month == getBirthMonth()) {
            salary += 100;
        }
        return salary;
    }
}

public class HourlyEmployee extends Employee {
    private double hourlyWage;
    private double hoursWorked;

    public HourlyEmployee(String name, int birthMonth, double hourlyWage, double hoursWorked) {
        super(name, birthMonth);
        this.hourlyWage = hourlyWage;
        this.hoursWorked = hoursWorked;
    }

    public double getHourlyWage() {
        return hourlyWage;
    }

    public double getHoursWorked() {
        return hoursWorked;
    }

    @Override
    public double getSalary(int month) {
        double salary = hourlyWage * hoursWorked;
        if (hoursWorked > 160) {
            salary += hourlyWage * 1.5 * (hoursWorked - 160);
        }
        if (month == getBirthMonth()) {
            salary += 100;
        }
        return salary;
    }
}

public class SalesEmployee extends Employee {
    private double monthlySales;
    private double commissionRate;

    public SalesEmployee(String name, int birthMonth, double monthlySales, double commissionRate) {
        super(name, birthMonth);
        this.monthlySales = monthlySales;
        this.commissionRate = commissionRate;
    }

    public double getMonthlySales() {
        return monthlySales;
    }

    public double getCommissionRate() {
        return commissionRate;
    }

    @Override
    public double getSalary(int month) {
        double salary = monthlySales * commissionRate;
        if (month == getBirthMonth()) {
            salary += 100;
        }
        return salary;
    }
}

public class BasePlusSalesEmployee extends SalesEmployee {
    private double baseSalary;

    public BasePlusSalesEmployee(String name, int birthMonth, double monthlySales, double commissionRate, double baseSalary) {
        super(name, birthMonth, monthlySales, commissionRate);
        this.baseSalary = baseSalary;
    }

    public double getBaseSalary() {
        return baseSalary;
    }

    @Override
    public double getSalary(int month) {
        double salary = super.getSalary(month) + baseSalary;
        if (month == getBirthMonth()) {
            salary += 100;
        }
        return salary;
    }
}

public class Test {
    public static void main(String[] args) {
        Employee[] employees = new Employee[5];
        employees[0] = new SalariedEmployee("John", 3, 5000);
        employees[1] = new HourlyEmployee("Mary", 4, 20, 180);
        employees[2] = new SalesEmployee("Tom", 5, 10000, 0.1);
        employees[3] = new BasePlusSalesEmployee("Jerry", 6, 8000, 0.12, 3000);
        employees[4] = new HourlyEmployee("Lucy", 7, 25, 150);

        int month = 5;
        for (Employee employee : employees) {
            System.out.println(employee.getName() + " " + employee.getSalary(month));
        }
    }
}

在 `Test` 类中，我们创建了一个 `Employee` 数组，分别创建了不同类型的 `Employee` 对象，并打印了 5 月份的工资。注意到我们在 `Employee` 类中实现了 `getSalary` 方法，而在每个子类中都重写了该方法，实现了不同类型员工的不同计算规则。同时，通过使用 `private` 修饰成员变量，实现了完全封装。