java声明一个名为person的抽象类，声明共有抽象方法void calsalary()，employee类继承自person类，定义带三个参数的构造方法 String name,int age,String occupation，覆写父类的printinfo(),覆写父类的抽象方法calsalary()，将salary赋值为5000，Worker类继承自person类，内容同employee一样，分别实例化employee类与worker类的对象，并调用各自构造方法初始化属性

好的，以下是 Java 代码实现：

// 声明抽象类 Person
abstract class Person {
    // 声明共有抽象方法 void calsalary()
    public abstract void calsalary();
}

// Employee 类继承自 Person 类
class Employee extends Person {
    String name;
    int age;
    String occupation;
    int salary;

    // 带三个参数的构造方法
    public Employee(String name, int age, String occupation) {
        this.name = name;
        this.age = age;
        this.occupation = occupation;
    }

    // 覆写父类的 printinfo() 方法
    public void printinfo() {
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("Occupation: " + occupation);
        System.out.println("Salary: " + salary);
    }

    // 覆写父类的抽象方法 calsalary()
    public void calsalary() {
        salary = 5000;
    }
}

// Worker 类同样继承自 Person 类
class Worker extends Person {
    String name;
    int age;
    String occupation;
    int salary;

    // 带三个参数的构造方法
    public Worker(String name, int age, String occupation) {
        this.name = name;
        this.age = age;
        this.occupation = occupation;
    }

    // 覆写父类的 printinfo() 方法
    public void printinfo() {
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("Occupation: " + occupation);
        System.out.println("Salary: " + salary);
    }

    // 覆写父类的抽象方法 calsalary()
    public void calsalary() {
        salary = 5000;
    }
}

// 实例化 Employee 类与 Worker 类的对象，并调用各自构造方法初始化属性
public class Main {
    public static void main(String[] args) {
        Employee emp = new Employee("John", 30, "Engineer");
        emp.calsalary();
        emp.printinfo();

        System.out.println();

        Worker worker = new Worker("Mary", 25, "Factory worker");
        worker.calsalary();
        worker.printinfo();
    }
}

希望这个例子可以帮助你更好地理解 Java 中的抽象类和继承。