吴裕雄--天生自然JAVA反射机制学习笔记：工厂设计模式

package org.lxh.demo15.factorydemo01 ;
interface Fruit{
    public void eat() ;    // 吃水果
}
class Apple implements Fruit{
    public void eat(){            // 覆写eat()方法
        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){
        Fruit fruit = null ;
        try{
            fruit = (Fruit)Class.forName(className).newInstance() ;
        }catch(Exception e){
            e.printStackTrace() ;
        }
        return fruit ;
    }
};
public class FactoryDemo01{
    public static void main(String args[]){
        Fruit f = Factory.getInstance("org.lxh.demo15.factorydemo01.Apple") ;
        if(f!=null){
            f.eat() ;
        }
    }
};

package org.lxh.demo15.factorydemo02 ;
import java.util.Properties ;
import java.io.File ;
import java.io.FileOutputStream ;
import java.io.FileInputStream ;
interface Fruit{
    public void eat() ;    // 吃水果
}
class Apple implements Fruit{
    public void eat(){            // 覆写eat()方法
        System.out.println("** 吃苹果");
    }
};
class Orange implements Fruit{
    public void eat(){
        System.out.println("** 吃橘子") ;
    }
};
class Init{
    public static Properties getPro(){
        Properties pro = new Properties() ;
        File f = new File("d:\fruit.properties") ;    // 找到属性文件
        try{
            if(f.exists()){    // 文件存在
                pro.load(new FileInputStream(f)) ;    // 读取属性
            }else{
                pro.setProperty("apple","org.lxh.demo15.factorydemo02.Apple") ;
                pro.setProperty("orange","org.lxh.demo15.factorydemo02.Orange") ;
                pro.store(new FileOutputStream(f),"FRUIT CLASS") ;
            }
        }catch(Exception e){}
        return pro ;
    }
};
class Factory{
    public static Fruit getInstance(String className){
        Fruit fruit = null ;
        try{
            fruit = (Fruit)Class.forName(className).newInstance() ;
        }catch(Exception e){
            e.printStackTrace() ;
        }
        return fruit ;
    }
};
public class FactoryDemo02{
    public static void main(String args[]){
        Properties pro = Init.getPro() ;
        Fruit f = Factory.getInstance(pro.getProperty("apple")) ;
        if(f!=null){
            f.eat() ;
        }
    }
};