定义Rectangle类（矩形类）,矩形的宽度和高度为double类型变量with，height；从键盘为with，height变量输入值，计算矩形的面积及周长。 要求：1.必须有构造器，构造器必须重载

2.必须有计算面积和周长的方法

Java代码如下：

import java.util.Scanner;

public class Rectangle {
    private double width;
    private double height;
    
    public Rectangle() {
        // 无参构造器
    }
    
    public Rectangle(double width, double height) {
        this.width = width;
        this.height = height;
    }
    
    public double getWidth() {
        return width;
    }
    
    public void setWidth(double width) {
        this.width = width;
    }
    
    public double getHeight() {
        return height;
    }
    
    public void setHeight(double height) {
        this.height = height;
    }
    
    public double getArea() {
        return width * height;
    }
    
    public double getPerimeter() {
        return 2 * (width + height);
    }
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("请输入矩形的宽度：");
        double width = sc.nextDouble();
        System.out.print("请输入矩形的高度：");
        double height = sc.nextDouble();
        
        Rectangle rect = new Rectangle(width, height);
        System.out.println("矩形的面积为：" + rect.getArea());
        System.out.println("矩形的周长为：" + rect.getPerimeter());
    }
}