用TransactionalEventListener实现事件监听

在实际项目中，难免会需要增加一些不影响主流程的业务，比如发短信，发邮件，计费，记账等等的操作。可以考虑异步解耦的思路去做，不失为一种优雅的解决方案。这样可以使得代码结构更加清晰，可扩展性更强。如果是在分布式应用下，不用应用之间可以考虑用MQ去做，如果是在单个项目里面的内部消息，可以考虑用spring的TransactionalEventListener去实现。

1，继承ApplicationEvent来定义自定义事件

package com.example.demo.event;

import org.springframework.context.ApplicationEvent;

/**
 * 事件定义
 *
 * @author lxw
 * @date 2020-08-19
 */
public class MyEvent extends ApplicationEvent {

    /**
     * 操作类型
     */
    private String operateType;

    /**
     * 操作明细
     */
    private String operateDetail;

    public MyEvent(String operateType, String operateDetail) {
        super("");
        this.operateType = operateType;
        this.operateDetail = operateDetail;
    }

    public String getOperateType() {
        return operateType;
    }

    public void setOperateType(String operateType) {
        this.operateType = operateType;
    }

    public String getOperateDetail() {
        return operateDetail;
    }

    public void setOperateDetail(String operateDetail) {
        this.operateDetail = operateDetail;
    }
}

2，使用TransactionalEventListener修饰监听回调方法

package com.example.demo.event;

import org.springframework.stereotype.Component;
import org.springframework.transaction.event.TransactionPhase;
import org.springframework.transaction.event.TransactionalEventListener;

/**
 * 事件监听器
 *
 * @author lxw
 * @date 2020-08-19
 */
@Component
public class MyEventListener {

    @TransactionalEventListener(phase = TransactionPhase.AFTER_COMMIT, value = MyEvent.class)
    public void handle(MyEvent myEvent) {
        System.out.println(myEvent);
        System.out.println(myEvent.getOperateDetail());
    }
}

3，使用ApplicationEventPublisher推送消息

package com.example.demo;

import com.example.demo.event.MyEvent;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.annotation.ComponentScan;

@ComponentScan({"com.example.demo.*"})
@SpringBootApplication
public class DemoApplication implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

    @Autowired
    private ApplicationEventPublisher eventPublisher;

    @Override
    public void run(String... args) throws Exception {
        MyEvent myEvent = new MyEvent("add", "张三做了一个新增的操作");

        eventPublisher.publishEvent(myEvent);

    }
}