工厂方法的核心是通过反射方式实例化具体产品类。
举例说明：工厂生产电子设备产品

1:创建抽象工厂：电子产品都有一个开机的功能

public abstract class DeviceBase {
    public abstract void start();
}

2:创建具体工厂

• 创建手机工厂

public class PhoneCreateFactory extends CreateDeviceFactory {
    @Override
    public <T extends DeviceBase> T createDevice(Class<T> tClass) {
        PhoneBase phoneBase = null;
        String className = tClass.getName();
        try {
            phoneBase = (PhoneBase) Class.forName(className).newInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return (T) phoneBase;
    }
}

• 创建电脑工厂

public class ComputerCreateFactory extends CreateDeviceFactory {
    @Override
    public <T extends DeviceBase> T createDevice(Class<T> tClass) {
        ComputerBase computerBase = null;
        try {
            computerBase = (ComputerBase) Class.forName(tClass.getName()).newInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return (T) computerBase;
    }
}

3:定义手机和电脑的基类和实体类

public abstract class DeviceBase {
    public abstract void start();
}

public abstract class PhoneBase extends DeviceBase {
    public abstract void call(String phoneNumber);
}

public abstract class ComputerBase extends DeviceBase{

}
public class Iphone extends PhoneBase {
    @Override
    public void call(String phoneNumber) {
        System.out.println("This is iphone call:"+phoneNumber);
    }

    @Override
    public void start() {
        System.out.println("This is iphone start!");
    }
}

public class XiaoMiphone extends PhoneBase {
    @Override
    public void call(String phoneNumber) {
        System.out.println("This is XiaoMi call:"+phoneNumber);
    }

    @Override
    public void start() {
        System.out.println("This is XiaoMi start!");
    }
}
public class MacComputer extends ComputerBase {
    @Override
    public void start() {
        System.out.println("This is MacComputer!");
    }
}

public class ImacComputer extends ComputerBase {
    @Override
    public void start() {
        System.out.println("This is IMacComputer!");
    }
}

4:客户端调用工厂方法开始生产设备

public static void main(String arg[]){
        CreateDeviceFactory createFactory = new ComputerCreateFactory();

        ImacComputer imacComputer = createFactory.createDevice(ImacComputer.class);
        imacComputer.start();

        MacComputer macComputer = createFactory.createDevice(MacComputer.class);
        macComputer.start();
        
        String phoneNumber = "18068409470";
        
        CreateDeviceFactory createDeviceFactory = new PhoneCreateFactory();
        Iphone iphone = createDeviceFactory.createDevice(Iphone.class);
        iphone.start();
        iphone.call(phoneNumber);

        XiaoMiphone xiaoMiphone = createDeviceFactory.createDevice(XiaoMiphone.class);
        xiaoMiphone.start();
        xiaoMiphone.call(phoneNumber);
    }