工厂设计模式

interface Fruit {
    public void eat() ;
}

class Apple implements Fruit {
   public void eat() {
       System.out.println("*** 吃苹果。") ;
   }
} 

class Orange implements Fruit {
   public void eat() {
       System.out.println("*** 吃橘子。") ;
   }
}

class Factory {
   public static Fruit getInstance(String className){
       if  ("apple".equals(className)){
           return new Apple() ;
       } else if ("orange".equals(className)) {
           return new Orange() ;
       } else {
           return null ;
       }
   }
}
public class TestDemo {
   public static void main(String args[]) {
       Fruit f = Factory.getInstance(args[0]) ;
       f.eat() ;
   } 
}