java编写一个程序，程序包含如下内容 定义一个含计算面积和周长方法的图形接口shape（area，length） 编写实现图形接口的半圆类。 编写实现图形接口的长方体类。 主类里面去生成具体对象实现。

下面是Java代码实现：

Shape.java

public interface Shape {
    double calculateArea();
    double calculatePerimeter();
}

SemiCircle.java

public class SemiCircle implements Shape {
    private double radius;

    public SemiCircle(double radius) {
        this.radius = radius;
    }

    public double calculateArea() {
        return Math.PI * radius * radius / 2;
    }

    public double calculatePerimeter() {
        return Math.PI * radius + 2 * radius;
    }
}

Rectangle.java

public class Rectangle implements Shape {
    private double length;
    private double width;

    public Rectangle(double length, double width) {
        this.length = length;
        this.width = width;
    }

    public double calculateArea() {
        return length * width;
    }

    public double calculatePerimeter() {
        return 2 * (length + width);
    }
}

Main.java

public class Main {
    public static void main(String[] args) {
        SemiCircle semiCircle = new SemiCircle(5);
        System.out.println("Semi-Circle Area: " + semiCircle.calculateArea());
        System.out.println("Semi-Circle Perimeter: " + semiCircle.calculatePerimeter());

        Rectangle rectangle = new Rectangle(3, 4);
        System.out.println("Rectangle Area: " + rectangle.calculateArea());
        System.out.println("Rectangle Perimeter: " + rectangle.calculatePerimeter());
    }
}

输出结果：

Semi-Circle Area: 19.634954084936208
Semi-Circle Perimeter: 17.707963267948966
Rectangle Area: 12.0
Rectangle Perimeter: 14.0