定时任务

SpringTask实现定时任务

优点:简单, 方便
缺点:时效性差一点

1.导包

spring-boot-starter-web 整合了SpringTask

2.代码

启动类

package com.example.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;
//开启SpringTask定时任务
@EnableScheduling
@SpringBootApplication
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

实现:

package com.heima.task.job;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import java.util.Date;
@Component
public class HelloJob {
    @Scheduled(cron = "0/5 * * * * ?") //每5秒执行一次
    public void sing(){
        System.out.println("当前执行时间："+new Date());
    }
}

@EnableScheduling 注解的作用是发现注解@Scheduled的任务并后台执行。
@Scheduled用于标注这个方法是一个定时任务的方法
cron时间表达式是一个字符串，字符串分6个域: 秒 分 时 日 月 周
cron时间表达式一般是用百度在线生成, 不需要去记它的规则
[

](https://blog.csdn.net/weixin_42960873/article/details/106849217)

RabbitMQ实现定时任务

优点：时效性好、承受并发量大
缺点：实现复杂度高、技术要求高

Linux配置

在线拉取
docker pull rabbitmq:3.8-management
加载镜像
docker load -i mq.tar
创建容器
docker run \
 -e RABBITMQ_DEFAULT_USER=momoda \
 -e RABBITMQ_DEFAULT_PASS=123321 \
 -v mq-plugins:/plugins \
 --name mq \
 --hostname mq \
 -p 15672:15672 \
 -p 5672:5672 \
 -d \
 rabbitmq:3.8-management

导包

<!--mq依赖 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-amqp</artifactId>
        </dependency>

配置

server:
  port: 8801
spring:
  application:
    name: task-demo
  rabbitmq:
    host: 192.168.200.130
    port: 5672
    virtual-host: /
    username: momoda
    password: 123321

代码

配置类

package com.example.rabbitConfig;
import org.springframework.amqp.core.*;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MqConfig {
    //交换机
    public static final String EX_A = "exchangeA";
    //死信交换机
    public static final String EX_B = "exchangeB";
    public static final String Q_A = "queueA";
    public static final String Q_B = "queueB";
    public static final String ROUTING_KEY_A = "exa-qa";
    public static final String ROUTING_KEY_B = "exb-qb";
    //声明 交换机
    @Bean(EX_A)
    public Exchange EX_A() {
        return new FanoutExchange(EX_A, true, false);
    }
    //声明 死信交换机
    @Bean(EX_B)
    public Exchange EX_B() {
        return new FanoutExchange(EX_B, true, false);
    }
    //声明 队列A
    @Bean(Q_A)
    public Queue Q_A() {
        Queue queue = new Queue(Q_A);
        //设置消息过期后转入哪个交换机
        queue.addArgument("x-dead-letter-exchange", EX_B);
        return queue;
    }
    //声明 队列B
    @Bean(Q_B)
    public Queue Q_B() {
        return new Queue(Q_B);
    }
    //绑定队列和交换机
    @Bean
    public Binding binding_A() {
        return BindingBuilder.bind(Q_A()).to(EX_A()).with(ROUTING_KEY_A).noargs();
    }
    //绑定队列和交换机
    @Bean
    public Binding binding_B() {
                                                       //设置KEY
        return BindingBuilder.bind(Q_B()).to(EX_B()).with(ROUTING_KEY_B).noargs();
    }
}

生产者

package com.example.producer;
import com.example.rabbitConfig.MqConfig;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageProperties;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import java.time.LocalDateTime;
@RestController
public class PublishProducer {
    @Autowired
    private RabbitTemplate rabbitTemplate;
    @GetMapping("/publish")
    public String publish(){
        MessageProperties messageProperties = new MessageProperties();
        //设置过期时间 单位:毫秒
        messageProperties.setExpiration("1000");
        //设置消息
        Message message = new Message("HelloWorld".getBytes(), messageProperties);
        //放到 交换机A  对应的key
        rabbitTemplate.convertAndSend(MqConfig.EX_A,"MqConfig.ROUTING_KEY_A ",message);
        System.out.println("消息发送时间" + LocalDateTime.now());
        return "OK";
    }
}

消费者

package com.example.listener;
import com.example.rabbitConfig.MqConfig;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Component;
import java.time.LocalDateTime;
@Component
public class PublishListener {
    //监听队列B
    @RabbitListener(queues = MqConfig.Q_B)
    public void publish(Message message) {
        System.out.println("接收消息时间" + LocalDateTime.now() + "  接收到消息" + new String(message.getBody()));
    }
}