1.什么是工厂模式

创建对象和使用对象的过程分开

2.工厂模式有哪几种

静态工厂

简单工厂

工厂方法

抽象工厂

3.Spring中哪些地方用到了工厂

beanFactory

4.简单工厂代码

链接：https://pan.baidu.com/s/1vnc-88f3JObElf2mX0wVjw 
提取码：33fx 

1）pom依赖

 <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.11.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.10</version>
        </dependency>
        <dependency>
            <groupId>commons-lang</groupId>
            <artifactId>commons-lang</artifactId>
            <version>2.6</version>
        </dependency>
    </dependencies>

2）接口

public interface PaymentService {
    void pay();
}

3）实现

import com.demo.service.PaymentService;
import org.springframework.stereotype.Service;

@Service
public class AlipayServiceImpl implements PaymentService {

    @Override
    public void pay() {
        System.out.println("支付宝支付");
    }
}

import com.demo.service.PaymentService;
import org.springframework.stereotype.Service;

@Service
public class WxPayServiceImpl implements PaymentService {

    @Override
    public void pay() {
        System.out.println("微信支付");
    }
}

4）简单工厂

import com.demo.service.PaymentService;
import com.demo.utils.SpringUtils;
import org.springframework.stereotype.Component;

@Component
public class PaymentFactory {

    public PaymentService getPaymentService(String payType) {
        return (PaymentService)SpringUtils.getBean(payType);
    }
}

5）工具类

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

@Component
public class SpringUtils implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    /**
     * 获取applicationContext
     */
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }

    /**
     * 通过name获取 Bean
     */
    public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    }

    /**
     * 通过class获取Bean
     */
    public static <T> T getBean(Class<T> clazz) {
        return getApplicationContext().getBean(clazz);
    }

    /**
     * 通过name,以及Clazz返回指定的Bean
     */
    public static <T> T getBean(String name, Class<T> clazz) {
        return getApplicationContext().getBean(name, clazz);
    }

}

6）控制层

import com.demo.factory.PaymentFactory;
import com.demo.service.PaymentService;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

@RestController
public class PaymentController {

    @Resource
    private PaymentFactory paymentFactory;

    @GetMapping("pay")
    public void pay(String payType) {
        PaymentService paymentService = paymentFactory.getPaymentService(payType);
        paymentService.pay();
    }
}

7）启动类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class AppFactory {

    public static void main(String[] args) {
        SpringApplication.run(AppFactory.class);
    }

}