Springt通過任務執行器（TaskExecutor）來實現多執行緒和併發程式設計。使用ThreadPoolTaskExecutor可實現一個基於執行緒池的TaskExecutor。而實際開發中任務一般是非阻礙的，即非同步的，所以我們要在配置類中通過@EnableAsync 開啟對非同步任務的支援，並通過實際執行Bean的方法中使用@Async註解來宣告其是一個非同步任務。

 1、配置類

package com.idark.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
@EnableAsync // 利用@EnableAsync註解開啟非同步任務支援
public class AsyncTaskConfig implements AsyncConfigurer{
    @Override
    public Executor getAsyncExecutor() { 
        // 配置類實現AsyncConfigurer介面並重寫 getAsyncExecutor 方法
        // 返回一個ThreadPoolTaskExecutor
        ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
        taskExecutor.setCorePoolSize(5);
        taskExecutor.setMaxPoolSize(10);
        taskExecutor.setQueueCapacity(25);
        taskExecutor.initialize();

        return taskExecutor;
    }

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

2、任務Service

package com.idark.async;

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

@Service
public class AsyncTaskService {
    
    // 通過@Async註解表明該方法是一個非同步方法，如果註解在類級別，表明該類下所有方法都是非同步方法，而這裡的方法自動被注入使用ThreadPoolTaskExecutor 作為 TaskExecutor
    @Async 
    public void executeAsyncTask(Integer i){
        System.out.println("執行非同步任務：" + i);
    }

    @Async
    public void executeAsyncTaskPlus(Integer i){
        System.out.println("執行非同步任務+1：" + (i+1));
    }
}
 

3、執行

package com.idark.async;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

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

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

        for(int i = 0; i < 50; i++){
            asyncTaskService.executeAsyncTask(i);
            asyncTaskService.executeAsyncTaskPlus(i);
        }
    }
}