一起学Java设计模式--简单工厂模式(不在23中设计模式之内)

(1) 简单工厂模式

使用简单工厂模式设计一个可以创建不同几何形状(Shape)的绘图工具类，如可创建圆形(Circle)、方形(Rectangle)和三角形(Triangle) 对象，每个几何图形都要有绘制draw()和擦除erase()两个方法，要求在绘制不支持的几何图形时，提示一个UnsupportedShapeException，绘制类图并编程实现。

//抽象图形
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!");
}
}
//工厂
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 "绘制不支持该几何图形！";
}

}

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();
}

}
}

运行结果：