一个接口多个实现类，如何动态调用

方法一：使用ApplicationContext（也可以借助配置文件）

1、一个支付接口

package com.niuniu.order.service.pay;public interface PayService {String pay();
}

2、两种支付方法实现类

package com.niuniu.order.service.pay.impl;import com.niuniu.order.service.pay.PayService;
import org.springframework.stereotype.Service;@Service
public class ZfbPayServiceImpl implements PayService {@Overridepublic String pay() {return "zfb";}
}

package com.niuniu.order.service.pay.impl;import com.niuniu.order.service.pay.PayService;
import org.springframework.stereotype.Service;@Service
public class WeiXinPayServiceImpl implements PayService {@Overridepublic String pay() {return "weixin";}
}

3、自定义MyServiceFactory类

package com.niuniu.order.service.pay;import com.niuniu.order.service.pay.impl.WeiXinPayServiceImpl;
import com.niuniu.order.service.pay.impl.ZfbPayServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Service;@Service
public class MyServiceFactory {@Autowiredprivate ApplicationContext applicationContext;public PayService getPayService(String beanName){switch (beanName){case ("zfbPayServiceImpl") :return applicationContext.getBean(ZfbPayServiceImpl.class);case ("weiXinPayServiceImpl") :return applicationContext.getBean(WeiXinPayServiceImpl.class);default:throw new IllegalArgumentException("Unknown service type!");}}
}

4、Controller调用

@Autowiredprivate MyServiceFactory myServiceFactory;@PostMapping("/pay")public Response pay(){
//        String s = myServiceFactory.getPayService("zfbPayServiceImpl").pay();String s = myServiceFactory.getPayService("weiXinPayServiceImpl").pay();return Response.ok(s);}

postman测试

方法二：使用Map存储各实现类的实例（策略模式）

package com.niuniu.order.service.pay;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.util.Map;@Service
public class MyServiceFactory2 {/*** key是bean名称*/private final Map<String, PayService> payServiceMap;@Autowiredpublic MyServiceFactory2(Map<String, PayService> payServiceMap) {this.payServiceMap = payServiceMap;}public PayService getPayService(String beanName){return payServiceMap.get(beanName);}
}

controller调用：

@Autowiredprivate MyServiceFactory2 myServiceFactory2;@PostMapping("/pay")public Response pay(){String s = myServiceFactory2.getPayService("zfbPayServiceImpl").pay();
//        String s = myServiceFactory2.getPayService("weiXinPayServiceImpl").pay();return Response.ok(s);}