使用反射来实现简单工厂模式

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package demo04;

public abstract class Pet {//抽象宠物类

}

class Dog extends Pet{}//Dog类

class Cat extends Pet{}//Cat类

class Pig extends Pet{}//Pig类

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package demo04;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.util.Properties;

public class PetFactory {

    public static Pet getPet(String   tag){

        Properties   p=new Properties();//声明properties对象

        try {

            p.load(new   FileInputStream("pet.properties"));//加载配置文件

        } catch   (Exception e) {

            e.printStackTrace();

        }

        Pet   pet=null;

        try {

            Class<!--?-->cla=Class.forName(p.getProperty(tag));//利用反射获取对象类

             Object   obj=cla.newInstance();//生成实例

             pet=(Pet)obj;//强制类型转换

        } catch   (Exception e) {

            e.printStackTrace();

        }

        return pet;

    }

}

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package demo04;

public class Test {

    public static void main(String[]   args) {

        Pet   pet=PetFactory.getPet("dog");

        System.out.println(pet);

    }

}