工厂设计模式 Factory

public class Demo1 {
    public static void main(String[] args) {
        System.out.println("买宝马");
        Car bmw = CarFactory("BMW");
        bmw.run();
        System.out.println("买大奔");
        Car benz = CarFactory("Benz");
        benz.run();
    }
    public static Car CarFactory(String carName) {
        if ("BMW".equals(carName)) {
            return new BMW();
        } else if ("Benz".equals(carName)) {
            return new Benz();
        } else {
            throw new RuntimeException("车型有误");
        }
    }
}
abstract class Car {
    public abstract void run();
}
class BMW extends Car {
    @Override
    public void run() {
        System.out.println("BMW跑跑");
    }
}
class Benz extends Car {
    @Override
    public void run() {
        System.out.println("Benz跑跑");
    }
}

public class Person {
    private int id;

    String name;

    public Person(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public Person() {
    }

    public void eat(int num) {
        System.out.println(name + "吃很" + num + "斤饭");
    }

    private static void sleep(int num) {
        System.out.println("明天睡上" + num + "小时");
    }

    public static void sum(int[] arr) {
        System.out.println("长度是：" + arr.length);
    }

    @Override
    public String toString() {
        return " 编号：" + this.id + " 姓名：" + this.name;
    }
}

com.it.reflect.Person
id=110
name=旺财

/*
工厂设计模式就是用于产生对象 的。
*/
class Car{}
class BMW extends Car{}
class BSJ extends Car{}

public class Demo1 {
    
    public static void main(String[] args) throws Exception {
        Person p = (Person) getInstance();
        System.out.println(p);
    }
    
    //需求： 编写一个工厂方法根据配置文件返回对应的对象。
    public static Object getInstance() throws Exception{
        //读取配置文件
        BufferedReader bufferedReader = new BufferedReader(new FileReader("info.txt"));
        //读取第一行 : 读取类文件的信息
        String className = bufferedReader.readLine();
        //通过完整类名获取对应 的Class对象
        Class clazz = Class.forName(className);
        //获取到对应的构造方法
        Constructor constructor = clazz.getDeclaredConstructor(null);
        constructor.setAccessible(true);
        Object o  = constructor.newInstance(null);
        //给对象设置对应的属性值
        String line = null;
        while((line = bufferedReader.readLine())!=null){
            String[] datas = line.split("=");
            Field field =clazz.getDeclaredField(datas[0]);
            //设置可以访问
            field.setAccessible(true);
            if(field.getType()==int.class){
                field.set(o, Integer.parseInt(datas[1]));
            }else{
                field.set(o, datas[1]);
            }
        }
        return o;
    }
}