題目：

1．   使用簡單工廠模式設計一個可以建立不同幾何形狀(Shape)的繪圖工具類，如可建立圓形(Circle)、矩形(Rectangle)、和三角形(Triangle)物件，每個幾何圖形均具有繪製和擦除兩個方法，要求在繪製不支援的幾何圖形時，丟擲一個異常(UnsupportedShapeException)，或實現一個簡單計算器，繪製類圖並程式設計實現。

類圖

package cn.factory1;

public class Circle implements Shape {
	public void init() {
		System.out.println("建立圓形。。。");
	}
}
 

package cn.factory1;

public class Rectangle implements Shape {
	public void init() {
		System.out.println("建立長方形。。。");
	}
}

package cn.factory1;

public interface Shape {
	public void init();
}

package cn.factory1;

public class ShapeFactory {
	public static Shape initShape(String name) throws Exception {
		if(name.equalsIgnoreCase("Circle")){
			System.out.println("圖形工廠生產圓形！");
			return new Circle();
		}
		else if(name.equalsIgnoreCase("Triangle")) {
			System.out.println("圖形工廠生產三角形！");
			return new Triangle();
		}
		else if(name.equalsIgnoreCase("Rectangle")) {
			System.out.println("圖形工廠生產長方形！");
			return new Rectangle();
		}
		else {
			throw new Exception("對不起，暫不能生產該種圖形！");
		}
	}
	public static void deleteShape(String name) throws Exception {
		if(name.equalsIgnoreCase("Circle")){
			System.out.println("已銷燬圓形！");
		}
		else if(name.equalsIgnoreCase("Triangle")) {
			System.out.println("已銷燬三角形！");
		}
		else if(name.equalsIgnoreCase("Rectangle")) {
			System.out.println("已銷燬長方形！");
		}
		else {
			throw new Exception("對不起，圖形工廠中沒有該種圖形！");
		}
	}	
}
 

package cn.factory1;

public class SimpleFac {
	public static void main(String[] args) {
		try {
			Shape shape;
			shape = ShapeFactory.initShape("Circle");
			shape.init();
			//shape = ShapeFactory.initShape("Triangle");
			//shape.init();
			//shape = ShapeFactory.initShape("Rectangle");
			//shape.init();
			//shape = ShapeFactory.initShape("app");
			//shape.init();
		}
		catch(Exception e) {
			System.out.println(e.getMessage());
		}
	}
}
 

package cn.factory1;

public class Triangle implements Shape {
	public void init() {
		System.out.println("建立三角形。。。");
	}
}

注意：這個程式是在SimpleFac類中執行