Spring高級話題-多線程

一、Spring中的多線程如何使用

• Spring通過TaskExecutor(任務執行器)來實現多線程和併發編程，通過ThreadPoolTaskExecutor實現以基於線程池的TaskExecutor。
• 在實際使用中，我們需要通過@EnableAsync來開啓對異步任務的支持，通過@Async來聲明一個異步任務

二、AsyncDemo

實現一個基於線程池的異步任務demo

配置類

package com.cactus.demo.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;

/**
 * Created by liruigao
 * Date: 2019-12-05 15:21
 * Description:
 * @EnableAsync 聲明開啓異步支持
 * 實現AsyncConfigurer接口並重寫對應方法，獲得需要的任務執行器
 */

@Configuration
@ComponentScan("com.cactus.demo.async")
@EnableAsync
public class AsyncConfig implements AsyncConfigurer {
    public Executor getAsyncExecutor() {
        ThreadPoolTaskExecutor threadPoolTaskExecutor = new ThreadPoolTaskExecutor();
        threadPoolTaskExecutor.setCorePoolSize(10);
        threadPoolTaskExecutor.setMaxPoolSize(20);
        threadPoolTaskExecutor.setQueueCapacity(30);
        threadPoolTaskExecutor.initialize();
        return threadPoolTaskExecutor;
    }

    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return null;
    }
}

方法bean

package com.cactus.demo.async;

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

/**
 * Created by liruigao
 * Date: 2019-12-05 15:28
 * Description:
 * @Async 聲明funcTwo爲異步方法，此方法自動注入使用配置類獲得任務執行器
 * @Async若置於類上，則此類所有方法均爲異步執行
 */

@Service
public class AsyncDemo {
    public void funcOne(Integer i) {
        System.out.println(Thread.currentThread().getName() + " - funcOne : " + i);
    }

    @Async
    public void funcTwo(Integer i) {
        try {
            Thread.sleep(50 - i);
            System.out.println(Thread.currentThread().getName() + " - funcTwo : " + i);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Main

package com.cactus.demo.async;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

/**
 * Created by liruigao
 * Date: 2019-12-05 15:30
 * Description:
 */


public class Main {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AsyncConfig.class);
        AsyncDemo asyncDemo = context.getBean(AsyncDemo.class);
        for (int i = 0; i < 5; i++) {
            asyncDemo.funcOne(i);
        }
        for (int i = 0; i < 5; i++) {
            asyncDemo.funcTwo(i);
        }
        context.close();
    }
}

Result

main - funcOne : 0
main - funcOne : 1
main - funcOne : 2
main - funcOne : 3
main - funcOne : 4
ThreadPoolTaskExecutor-5 - funcTwo : 4
ThreadPoolTaskExecutor-4 - funcTwo : 3
ThreadPoolTaskExecutor-3 - funcTwo : 2
ThreadPoolTaskExecutor-2 - funcTwo : 1
ThreadPoolTaskExecutor-1 - funcTwo : 0