Spring Boot实战笔记(六)-- Spring高级话题(多线程)

时间:2022-08-01 23:20:02

一、多线程

  Springt通过任务执行器(TaskExecutor)来实现多线程和并发编程。使用ThreadPoolTaskExecutor可实现一个基于线程池的TaskExecutor。而实际开发中任务一般是非阻碍的,即异步的,所以我们要在配置类中通过@EnableAsync 开启对异步任务的支持,并通过实际执行Bean的方法中使用@Async注解来声明其是一个异步任务。

示例:

  1.配置类。

package com.ecworking.async;

import org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.AsyncConfigurer;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

import java.util.concurrent.Executor;

@Configuration
@ComponentScan("com.ecworking.async")
@EnableAsync // 利用@EnableAsync注解开启异步任务支持
public class AsyncTaskConfig implements AsyncConfigurer{
    @Override
    public Executor getAsyncExecutor() { // 配置类实现AsyncConfigurer接口并重写 getAsyncExecutor 方法,并返回一个 ThreadPoolTaskExecutor,这样我们就获得了一个线程池 taskExecutor
        ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
        taskExecutor.setCorePoolSize(5);
        taskExecutor.setMaxPoolSize(10);
        taskExecutor.setQueueCapacity(25);
        taskExecutor.initialize();

        return taskExecutor;
    }

    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return null;
    }
}

  2.任务执行类

package com.ecworking.async;

import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;

@Service
public class AsyncTaskService {

    @Async // 通过@Async注解表明该方法是一个异步方法,如果注解在类级别,表明该类下所有方法都是异步方法,而这里的方法自动被注入使用ThreadPoolTaskExecutor 作为 TaskExecutor
    public void executeAsyncTask(Integer i){
        System.out.println("执行异步任务:" + i);
    }

    @Async
    public void executeAsyncTaskPlus(Integer i){
        System.out.println("执行异步任务+1:" + (i+1));
    }
}

  3.运行

package com.ecworking.async;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Mian {
    public static void main(String[] args){
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AsyncTaskConfig.class);

        AsyncTaskService asyncTaskService = context.getBean(AsyncTaskService.class);

        for(int i = 0; i < 10; i++){
            asyncTaskService.executeAsyncTask(i);
            asyncTaskService.executeAsyncTaskPlus(i);
        }
    }
}

运行结果是并发执行而不是顺序执行

Spring Boot实战笔记(六)-- Spring高级话题(多线程)