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;
     }

 }