Guava中的EventBus使用笔记

Guava中的EventBus使用笔记

物料准备：

1.引入guava依赖

2.定义一个EventBusUtil工具类

3.定义自定义的事件以及监听逻辑

4.测试发布事件效果

引入guava依赖

<dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
            <version>25.1-jre</version>
        </dependency>

定义一个EventBusUtil工具类

package com.example.demo.service.guava;


import com.google.common.eventbus.AsyncEventBus;
import com.google.common.eventbus.EventBus;
import java.util.concurrent.Executor;


public class EventBusUtil {
    private static EventBus eventBus;
    private static AsyncEventBus asyncEventBus;
    private static Executor executor = new Executor() {
        public void execute(Runnable command) {
            new Thread(command).start();
        }
    };
    //双重锁单例模式
    private static AsyncEventBus getAsynEventBus(){
        if(asyncEventBus==null){
            synchronized (AsyncEventBus.class){
                if(asyncEventBus==null){
                    asyncEventBus = new AsyncEventBus(executor);
                }
            }
        }
        return asyncEventBus;
    }
    //双重锁单例模式
    private static EventBus getEventBus(){
        if(eventBus==null){
            synchronized (EventBus.class){
                if(eventBus==null){
                    eventBus = new EventBus();
                }
            }
        }
        return eventBus;
    }
    public static void post(Object event){
        getEventBus().post(event);
    }
    //异步方式发送事件
    public static void asyncPost(Object event){
        getAsynEventBus().post(event);
    }
    public static void registerEventBus(Object object){
        getEventBus().register(object);
    }

    public static void registerAsynEventBus(Object object){
        getAsynEventBus().register(object);
    }
}

自定义事件类

public class CustomEvent {
    private int age;
    public CustomEvent(int age){
        this.age = age;
    }
    public int getAge(){
        return this.age;
    }
}

自定义监听逻辑

package com.example.demo.service.guava;

import com.google.common.eventbus.Subscribe;
import org.springframework.stereotype.Component;
import java.time.Instant;

@Component
public class EventListener1 {

    @Subscribe
    public void test1(CustomEvent event){
        System.out.println(Instant.now() +"监听者1-->订阅者1,收到事件："+event.getAge()+"，线程号为："+Thread.currentThread().getName());
        try {
            Thread.sleep(300);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    @Subscribe
    public void test2(CustomEvent event){
        System.out.println(Instant.now() +"监听者1-->订阅者2,收到事件："+event.getAge()+"，线程号为："+Thread.currentThread().getName());
    }

}

package com.example.demo.service.guava;

import com.google.common.eventbus.Subscribe;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

@Slf4j
@Component
public class EventListener2 {
    @Subscribe
    public void test7051(CustomEvent event){
        log.info("test7051-evt:{}",event.getAge());
    }

    @Subscribe
    public void test7052(CustomEvent event){
        log.info("test7052-evt:{}",event.getAge());
    }

    @Subscribe
    public void test7053(CustomEvent event){
        log.info("test7053-evt:{}",event.getAge());
    }
}

测试发布事件效果

测试发送普通事件(阻塞)

    @Test
    void test111902(){
        EventListener1 listener1 = new EventListener1();
        EventListener2 listener2 = new EventListener2();
        EventBusUtil.registerEventBus(listener1);
        EventBusUtil.registerEventBus(listener2);
        CustomEvent customEvent = new CustomEvent(23);
        EventBusUtil.post(customEvent);
    }

[INFO] [2023-07-05 19:07:38.110] [main] com.example.demo.OtherTests.logStarted:61 --> Started OtherTests in 5.046 seconds (JVM running for 7.636)
2023-07-05T11:07:38.987Z监听者1-->订阅者2,收到事件：23，线程号为：main
2023-07-05T11:07:38.988Z监听者1-->订阅者1,收到事件：23，线程号为：main
[INFO] [2023-07-05 19:07:39.288] [main] com.example.demo.service.guava.EventListener2.test7053:40 --> test7053-evt:23
[INFO] [2023-07-05 19:07:39.288] [main] com.example.demo.service.guava.EventListener2.test7051:29 --> test7051-evt:23
[INFO] [2023-07-05 19:07:39.288] [main] com.example.demo.service.guava.EventListener2.test7052:35 --> test7052-evt:23

---

测试发送异步事件 (非阻塞)

  @Test
    void testGuavaAsyncEvt(){
        EventListener2 listener2 = new EventListener2();
        EventBusUtil.registerAsynEventBus(listener2);

        CustomEvent customEvent = new CustomEvent(23);
        CustomEvent customEvent2 = new CustomEvent(50);
        EventBusUtil.asyncPost(customEvent);
        EventBusUtil.asyncPost(customEvent2);

    }

[INFO] [2023-07-05 19:08:59.992] [main] com.example.demo.OtherTests.logStarted:61 --> Started OtherTests in 4.951 seconds (JVM running for 7.378)
[INFO] [2023-07-05 19:09:00.474] [Thread-3] com.example.demo.service.guava.EventListener2.test7051:29 --> test7051-evt:23
[INFO] [2023-07-05 19:09:00.476] [Thread-4] com.example.demo.service.guava.EventListener2.test7053:40 --> test7053-evt:23
[INFO] [2023-07-05 19:09:00.476] [Thread-2] com.example.demo.service.guava.EventListener2.test7052:35 --> test7052-evt:23
[INFO] [2023-07-05 19:09:00.479] [Thread-6] com.example.demo.service.guava.EventListener2.test7051:29 --> test7051-evt:50
[INFO] [2023-07-05 19:09:00.481] [Thread-7] com.example.demo.service.guava.EventListener2.test7053:40 --> test7053-evt:50
[INFO] [2023-07-05 19:09:00.503] [Thread-5] com.example.demo.service.guava.EventListener2.test7052:35 --> test7052-evt:50