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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 */@Componentpublic 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 */@Componentpublic 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 */@Componentpublic class BeanConfig implements InitializingBean, ApplicationContextAware {
       private Map
   
     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
    
      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 */@RestControllerpublic 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();    }}

5、启动运行与结果

访问：http://localhost:8080/get?id=UserReaderImpl1

访问：http://localhost:8080/get?id=UserReaderImpl2

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