【spring】spring自带的观察者模式【转载】

ゞ浴缸里的玫瑰 2023-01-13 05:47 59阅读 0赞

> `前言`

转载自：[https://mp.weixin.qq.com/s?srcid=0415igWGyJhQOhntXUaSd56G][https_mp.weixin.qq.com_s_srcid_0415igWGyJhQOhntXUaSd56G]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3MxNDQxMTAxMjY1_size_16_color_FFFFFF_t_70]

> `代码示例`

*  首先，观察目标类

import lombok.Getter;
    import org.springframework.context.ApplicationEvent;
    
    /** * @author qilong.sun * @version v1.0 * @time 2021/4/16 9:33 * @title 观察者目标类 * @description */
    @Getter
    public class JavaStackEvent extends ApplicationEvent { 
    
        /** * Create a new {@code ApplicationEvent}. * * @param source the object on which the event initially occurred or with * which the event is associated (never {@code null}) */
        public JavaStackEvent(Object source) { 
            super(source);
        }
    }

*  然后，观察者类

import lombok.NonNull;
    import lombok.RequiredArgsConstructor;
    import org.springframework.context.ApplicationListener;
    import org.springframework.scheduling.annotation.Async;
    
    /** * @author qilong.sun * @version v1.0 * @time 2021/4/16 9:42 * @title 观察者类 * @description */
    @RequiredArgsConstructor
    public class ReaderListener implements ApplicationListener<JavaStackEvent> { 
    
        @NonNull
        private String name;
    
        private String article;
    
        @Async
        @Override
        public void onApplicationEvent(JavaStackEvent event) { 
            // 更新文章
            updateArticle(event);
        }
    
        private void updateArticle(JavaStackEvent event) { 
            this.article = (String) event.getSource();
            System.out.printf("我是读者：%s，文章已更新为：%s\n", this.name, this.article);
        }
    
    }

*  最后，测试配置类；也就是用户实例

import lombok.extern.slf4j.Slf4j;
    import org.springframework.boot.CommandLineRunner;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    /** * @author qilong.sun * @version v1.0 * @time 2021/4/16 9:53 * @title 测试配置类 * @description */
    @Slf4j
    @Configuration
    public class ObserverConfiguration { 
    
        @Bean
        public CommandLineRunner commandLineRunner(ApplicationContext context) { 
            return (args) -> { 
                log.info("发布事件：什么是观察者模式？");
                context.publishEvent(new JavaStackEvent("什么是观察者模式？"));
            };
        }
    
        @Bean
        public ReaderListener readerListener1(){ 
            return new ReaderListener("小明");
        }
    
        @Bean
        public ReaderListener readerListener2(){ 
            return new ReaderListener("小张");
        }
    
        @Bean
        public ReaderListener readerListener3(){ 
            return new ReaderListener("小爱");
        }
    
    }

> `测试`

启动项目，控制台打印信息：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3MxNDQxMTAxMjY1_size_16_color_FFFFFF_t_70 1]

> `理解`

[https_mp.weixin.qq.com_s_srcid_0415igWGyJhQOhntXUaSd56G]: https://mp.weixin.qq.com/s?srcid=0415igWGyJhQOhntXUaSd56G&scene=22&sharer_sharetime=1618453332302&mid=2247495875&sharer_shareid=304c34be1ddc2c7df7787d080e240ce2&sn=3a1e1143c5a9a08abee885e632b1dc15&idx=1&__biz=MzIyNzc1ODQ0MQ%3D%3D&chksm=e85ee8c5df2961d3ab215fd68c2c29f9523c6c00c13b500ef014b2449d12835130a25c5c69ad&mpshare=1#rd
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3MxNDQxMTAxMjY1_size_16_color_FFFFFF_t_70]: /images/20221022/9fc6374a0b1c413d961806613602d3fd.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3MxNDQxMTAxMjY1_size_16_color_FFFFFF_t_70 1]: /images/20221022/e99c7e231ac544959a5a68cfeaac8dd3.png