一起學Java設計模式--簡單工廠模式(不在23中設計模式之內)

(1) 簡單工廠模式

使用簡單工廠模式設計一個可以創建不同幾何形狀(Shape)的繪圖工具類，如可創建圓形(Circle)、方形(Rectangle)和三角形(Triangle) 對象，每個幾何圖形都要有繪製draw()和擦除erase()兩個方法，要求在繪製不支持的幾何圖形時，提示一個UnsupportedShapeException，繪製類圖並編程實現。

//抽象圖形
public interface Shape{
	void draw();
	void erase();
} 
public class Circle implements Shape{
	public void draw(){
		System.out.println("Circle draw!");
	}	
	public void erase(){
		System.out.println("Circle erasing!");
	}
} 
public class Rectangle implements Shape{
	public void draw(){
		System.out.println("Rectangle draw!");
	}
	public void erase(){
		System.out.println("Rectangle erasing!");
	}
} 
public class Triangle implements Shape{
	public void draw(){
		System.out.println("Triangle draw!");
	}
	public void erase(){
		System.out.println("Triangle erasing!");
	}
}
//工廠
import java.lang.*;

public class ShapeFactory{
	public static Shape produceShape(String shapeName) 
			throws UnsupportedShapeException{
		if(shapeName.equals("circle")){
			return new Circle();
		}else if(shapeName.equals("rectangle")){
			return new Rectangle();
		}else if(shapeName.equals("triangle")){
			return new Triangle();
		}else{
			throw new UnsupportedShapeException();
		}
	}
}
class UnsupportedShapeException extends Exception{  
	public String toString(){
		return "繪製不支持該幾何圖形！";
	}
	
}

public class ShapeClient{
	public static void main(String[] args){
		Shape circle = null;
		Shape rectangle = null;
		Shape triangle = null;
		
		Shape diamond = null;
		try{
			circle = ShapeFactory.produceShape("circle");
			rectangle = ShapeFactory.produceShape("rectangle");
			triangle = ShapeFactory.produceShape("triangle");
			
			
		circle.draw();
		circle.erase();
		
		rectangle.draw();
		rectangle.erase();
		
		triangle.draw();
		triangle.erase();
		
		
		}catch(UnsupportedShapeException e){
			e.printStackTrace(); 
		}
		
		try{
			diamond = ShapeFactory.produceShape("diamond");
			
			diamond.draw();
			diamond.erase();
		}catch(UnsupportedShapeException e){
			e.printStackTrace();
		}
		
		
		
	}
}

運行結果：