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Springboot对多线程的支持详解

这两天看阿里的JAVA开发手册,到多线程的时候说永远不要用 new Thread()这种方式来使用多线程。确实是这样的,我一直在用线程池,到了springboot才发现他已经给我们提供了很方便的线程池机制。
本博客代码托管在github上https://github.com/gxz0422042...

一、介绍

Spring是通过任务执行器(TaskExecutor)来实现多线程和并发编程,使用ThreadPoolTaskExecutor来创建一个基于线城池的TaskExecutor。在使用线程池的大多数情况下都是异步非阻塞的。我们配置注解@EnableAsync可以开启异步任务。然后在实际执行的方法上配置注解@Async上声明是异步任务。

二、配置类

配置类代码如下:

package com.spartajet.springbootlearn.thread;

import org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler;
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;

/**
 * @description
 * @create 2017-02-22 下午11:53
 * @email gxz04220427@163.com
 */
@Configuration
@EnableAsync
public class ThreadConfig implements AsyncConfigurer {

    /**
     * The {@link Executor} instance to be used when processing async
     * method invocations.
     */
    @Override
    public Executor getAsyncExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(5);
        executor.setMaxPoolSize(15);
        executor.setQueueCapacity(25);
        executor.initialize();
        return executor;
    }

    /**
     * The {@link AsyncUncaughtExceptionHandler} instance to be used
     * when an exception is thrown during an asynchronous method execution
     * with {@code void} return type.
     */
    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return null;
    }
}

解读:

  1. 利用EnableAsync来开启Springboot对于异步任务的支持
  2. 配置类实现接口AsyncConfigurator,返回一个ThreadPoolTaskExecutor线程池对象。

三、任务执行

任务执行代码:

package com.spartajet.springbootlearn.thread;

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

/**
 * @description
 * @create 2017-02-23 上午12:00
 * @email gxz04220427@163.com
 */
@Service
public class AsyncTaskService {
    @Async
    public void executeAsyncTask(int i) {
        System.out.println("线程" + Thread.currentThread().getName() + " 执行异步任务:" + i);
    }
}

代码解读:

  1. 通过@Async注解表明该方法是异步方法,如果注解在类上,那表明这个类里面的所有方法都是异步的。

四、测试代码

package com.spartajet.springbootlearn;

import com.spartajet.springbootlearn.thread.AsyncTaskService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith (SpringRunner.class)
@SpringBootTest
public class SpringbootLearnApplicationTests {
    @Autowired
    private AsyncTaskService asyncTaskService;

    @Test
    public void contextLoads() {
    }

    @Test
    public void threadTest() {
        for (int i = 0; i < 20; i++) {
            asyncTaskService.executeAsyncTask(i);
        }
    }

}

测试结果:

线程ThreadPoolTaskExecutor-4 执行异步任务:3
线程ThreadPoolTaskExecutor-2 执行异步任务:1
线程ThreadPoolTaskExecutor-1 执行异步任务:0
线程ThreadPoolTaskExecutor-1 执行异步任务:7
线程ThreadPoolTaskExecutor-1 执行异步任务:8
线程ThreadPoolTaskExecutor-1 执行异步任务:9
线程ThreadPoolTaskExecutor-1 执行异步任务:10
线程ThreadPoolTaskExecutor-5 执行异步任务:4
线程ThreadPoolTaskExecutor-3 执行异步任务:2
线程ThreadPoolTaskExecutor-5 执行异步任务:12
线程ThreadPoolTaskExecutor-1 执行异步任务:11
线程ThreadPoolTaskExecutor-2 执行异步任务:6
线程ThreadPoolTaskExecutor-4 执行异步任务:5
线程ThreadPoolTaskExecutor-2 执行异步任务:16
线程ThreadPoolTaskExecutor-1 执行异步任务:15
线程ThreadPoolTaskExecutor-5 执行异步任务:14
线程ThreadPoolTaskExecutor-3 执行异步任务:13
线程ThreadPoolTaskExecutor-1 执行异步任务:19
线程ThreadPoolTaskExecutor-2 执行异步任务:18
线程ThreadPoolTaskExecutor-4 执行异步任务:17

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