因为项目需要，我们有一个功能的接口UserReader。其他的类都是实现这个接口。那么会有多个实现UserReader接口的实现类。现在需要在程序中动态的去调用不通实现类中的方法getUser（）。下面既是功能实现代码：

1、添加接口

package com.example.mavenceshi.service;

/** * @author by CLP * @Classname UserReader * @Description * @Date 2020/9/8 15:16 */
public interface UserReader { 

    String getUser();
}

2、创建实现类

1）实现类UserReaderImpl1

package com.example.mavenceshi.service.impl;

import com.example.mavenceshi.service.UserReader;
import org.springframework.stereotype.Component;

/** * @author by CLP * @Classname UserReader1 * @Description * @Date 2020/9/8 15:17 */
@Component
public class UserReaderImpl1 implements UserReader { 
    @Override
    public String getUser() { 
           return "访问的UserReaderImpl1";
    }
}

2)实现类 UserReaderImpl2

package com.example.mavenceshi.service.impl;

import com.example.mavenceshi.service.UserReader;
import org.springframework.stereotype.Component;

/** * @author by CLP * @Classname UserReaderImpl2 * @Description * @Date 2020/9/8 15:18 */
@Component
public class UserReaderImpl2 implements UserReader { 
    @Override
    public String getUser() { 
          return "访问的UserReaderImpl2";
    }
}

3、获取实现类的相关接口

package com.example.mavenceshi.config;

import com.example.mavenceshi.service.UserReader;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

import java.util.HashMap;
import java.util.Map;

/** * @author by CLP * @Classname BeanConfig * @Description * @Date 2020/9/8 15:28 */
@Component
public class BeanConfig implements InitializingBean, ApplicationContextAware { 
    private Map<String, UserReader> queryServiceImplMap = new HashMap<>();
    private ApplicationContext applicationContext;

    public UserReader createQueryService(String type) { 

        UserReader userReader = queryServiceImplMap.get(type);
        if (userReader == null) { 
            return queryServiceImplMap.get("UserReader1Impl");
        }
        return userReader;
    }

    @Override
    public void afterPropertiesSet() throws Exception { 
        Map<String, UserReader> beanMap = applicationContext.getBeansOfType(UserReader.class);
        //遍历该接口的所有实现，将其放入map中
        for (UserReader serviceImpl : beanMap.values()) { 
            queryServiceImplMap.put(serviceImpl.getClass().getSimpleName(), serviceImpl);
        }
    }

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

4、写一个controller接口，实现动态调用

package com.example.mavenceshi.controller;

import com.example.mavenceshi.config.BeanConfig;
import com.example.mavenceshi.service.UserReader;
import com.example.mavenceshi.service.impl.UserReaderImpl1;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/** * @author by CLP * @Classname controller * @Description * @Date 2020/9/8 15:18 */
@RestController
public class controller { 
    @Autowired
    private UserReaderImpl1 userReader;
    @Autowired
    private BeanConfig beanConfig;

    @GetMapping("/get")
    public String get(String id) { 
        UserReader queryService = beanConfig.createQueryService(id);
        System.out.println(queryService.toString());
        return queryService.getUser();

    }
}