玩转ApplicationContextAware

当一个类实现了这个接口之后，这个类就可以方便地获得 ApplicationContext 中的所有bean。换句话说，就是这个类可以直接获取Spring配置文件中，所有有引用到的bean对象。结合工厂模式写个demo，比如说ApplicationContext 中有两个发送短信的bean，一个是叫移动的Bean，另一个是叫电信的Bean，那么在某一个场景下，你只要用某一个Bean，那么到底用哪一个取决于你自已，也就是你所传的参数。

1.类ChannelFactory实现了ApplicationContextAware接口

package com.tanlu.user.factory;

import org.springframework.beans.BeansException;

import org.springframework.context.ApplicationContext;

import org.springframework.context.ApplicationContextAware;

import org.springframework.stereotype.Component;

@Component

public class ChannelFactory implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    @Override

    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {

        this.applicationContext = applicationContext;

    }

    /**

     * 获取applicationContext

     * @return

     */

    public static ApplicationContext getApplicationContext() {

        return applicationContext;

    }

    public Object getBean(String param) {

        return applicationContext.getBean(param);

    }

    /**

     * 通过class获取Bean.

     * @param clazz

     * @param <T>

     * @return

     */

    public static <T> T getBean(Class<T> clazz){

        return getApplicationContext().getBean(clazz);

    }

    public SendMessageChannel getChannel(String code){

        switch (code){

            case "1":

                return applicationContext.getBean(YiDongMobile.class);

            case "2":

                return applicationContext.getBean(DianXinMobile.class);

            default:

                return applicationContext.getBean(YiDongMobile.class);

        }

    }

}

2.ApplicationContext 中的两个Bean

 package com.tanlu.user.factory;

 import com.tanlu.user.model.ResponseData;

 import org.springframework.stereotype.Component;

 @Component

 public class DianXinMobile implements SendMessageChannel {

     @Override

     public ResponseData sendMsg(String s1) {

         ResponseData data = ResponseData.susscce();

         data.setMessage("电信");

         System.out.println("中国电信发送短信");

         return data;

     }

 }

 package com.tanlu.user.factory;

 import com.tanlu.user.model.ResponseData;

 import org.springframework.stereotype.Component;

 /**

  *移动

  */

 @Component

 public class YiDongMobile implements SendMessageChannel {

     @Override

     public ResponseData sendMsg(String s1) {

         ResponseData data = ResponseData.susscce();

         data.setMessage("移动");

         System.out.println("我是中国移动发送短信");

         return data;

     }

 }

 package com.tanlu.user.factory;

 import com.tanlu.user.model.ResponseData;

 public interface SendMessageChannel {

     /**

      * 发送短信

      * @param s1

      */

     public ResponseData sendMsg(String s1);

 }

3.测试，这时候你可以随意注入实现ApplicationContextAware接口的类。

 package com.tanlu.user.controller;

 import com.alibaba.fastjson.JSON;

 import com.tanlu.user.factory.ChannelFactory;

 import com.tanlu.user.model.ResponseData;

 import com.tanlu.user.model.dto.SendMessageDto;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 import org.springframework.beans.factory.annotation.Autowired;

 import org.springframework.web.bind.annotation.*;

 @RequestMapping("/message")

 @RestController

 public class SendMessageController {

     private static final Logger logger = LoggerFactory.getLogger(SendMessageController.class);

     @Autowired

     private ChannelFactory channelFactory;

     /**

      * 工厂类demo

      * @param dto

      * @return

      * @throws Exception

      */

     @RequestMapping(value = "/channel", method = RequestMethod.POST, produces = "application/json")

     public ResponseData sendMsgCode(@RequestBody SendMessageDto dto) throws Exception {

         String code = dto.getCode();

         logger.info("code :"+code);

         ResponseData data = channelFactory.getChannel(code).sendMsg(code);

         System.out.println("test applicationcontextaware :"+ JSON.toJSON(data));

         return data;

     }

 }