用Java实现为某公司编写一个工资支付系统，用于计算某一类员工的月薪。该公司共有四类员工：领固定月薪的（SalariedEmployee）；计时取酬的（HourlyEmployee，如果一月工时超过160小时，则还需对额外的工时支付加班费）；按销售额提成（CommissionEmployee）的和带底薪并按销售额提成的（BasePlusCommissionEmployee），其继承层次结构如下所示。已知每类员工均有表示员工工号、姓名和出生年月的属性，和用于计算员工月薪的方法。创建一个Employee变量数

据，分别存储不同类型的员工信息，并计算他们的月薪。

以下是Java代码实现：

public abstract class Employee {
    private String employeeId;
    private String name;
    private int birthYear;

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

    public String getEmployeeId() {
        return employeeId;
    }

    public String getName() {
        return name;
    }

    public int getBirthYear() {
        return birthYear;
    }

    public abstract double getMonthlySalary();
}

public class SalariedEmployee extends Employee {
    private double monthlySalary;

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

    @Override
    public double getMonthlySalary() {
        return monthlySalary;
    }
}

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

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

    @Override
    public double getMonthlySalary() {
        if (hoursWorked <= 160) {
            return hourlyWage * hoursWorked;
        } else {
            return hourlyWage * 160 + hourlyWage * 1.5 * (hoursWorked - 160);
        }
    }
}

public class CommissionEmployee extends Employee {
    private double commissionRate;
    private double grossSales;

    public CommissionEmployee(String employeeId, String name, int birthYear, double commissionRate, double grossSales) {
        super(employeeId, name, birthYear);
        this.commissionRate = commissionRate;
        this.grossSales = grossSales;
    }

    @Override
    public double getMonthlySalary() {
        return commissionRate * grossSales;
    }
}

public class BasePlusCommissionEmployee extends CommissionEmployee {
    private double baseSalary;

    public BasePlusCommissionEmployee(String employeeId, String name, int birthYear, double commissionRate, double grossSales, double baseSalary) {
        super(employeeId, name, birthYear, commissionRate, grossSales);
        this.baseSalary = baseSalary;
    }

    @Override
    public double getMonthlySalary() {
        return super.getMonthlySalary() + baseSalary;
    }
}

public class PayrollSystem {
    public static void main(String[] args) {
        SalariedEmployee salariedEmployee = new SalariedEmployee("001", "John Doe", 1980, 5000);
        HourlyEmployee hourlyEmployee = new HourlyEmployee("002", "Jane Smith", 1985, 20, 180);
        CommissionEmployee commissionEmployee = new CommissionEmployee("003", "Bob Johnson", 1975, 0.1, 10000);
        BasePlusCommissionEmployee basePlusCommissionEmployee = new BasePlusCommissionEmployee("004", "Mary Brown", 1990, 0.08, 12000, 3000);

        Employee[] employees = {salariedEmployee, hourlyEmployee, commissionEmployee, basePlusCommissionEmployee};

        for (Employee employee : employees) {
            System.out.println("Employee ID: " + employee.getEmployeeId());
            System.out.println("Name: " + employee.getName());
            System.out.println("Birth Year: " + employee.getBirthYear());
            System.out.println("Monthly Salary: " + employee.getMonthlySalary());
            System.out.println();
        }
    }
}

在主函数中，我们创建了四个不同类型的员工，并将它们存储在一个数组中，然后使用循环遍历数组，并输出每个员工的信息和月薪。