Java开启异步的两种方式

package com.cc.md.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

import java.util.concurrent.ThreadPoolExecutor;

/** IO型的线程池
 * @author CC
 * @since 2023/5/23 0023
 */
@Configuration
@EnableAsync
public class IoThreadPool {

    public static final int THREAD_SIZE = 2 * (Runtime.getRuntime().availableProcessors());
    
    public static final int QUEUE_SIZE = 1000;

    @Bean(name = "myIoThreadPool")
    public ThreadPoolTaskExecutor threadPoolExecutor(){
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(THREAD_SIZE);
        executor.setMaxPoolSize(THREAD_SIZE);
        executor.setQueueCapacity(QUEUE_SIZE);
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());
        executor.setKeepAliveSeconds(60);
        executor.setAllowCoreThreadTimeOut(true);
        executor.setAwaitTerminationSeconds(300);
        executor.setWaitForTasksToCompleteOnShutdown(true);
        executor.setThreadNamePrefix("myIo-Th-Pool-");
        executor.initialize();
        return executor;
    }
}

    1 @Async：类上，说明整个类中的方法都是异步。必须写我们自己配置的线程池 —— ("myIoThreadPool")
    2 @Async：方法上，说明这个方法是异步。不用写我们自己配置的线程池

package com.cc.md.service;

/**
 * @author CC
 * @since 2023/5/24 0024
 */
public interface IAsyncService {

    /** 异步方法1
     * @since 2023/5/24 0024
     * @author CC
     **/
    void async1();

    /** 异步方法2
     * @since 2023/5/24 0024
     * @author CC
     **/
    void async2();

}

package com.cc.md.service.impl;

import com.cc.md.service.IAsyncService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;

/** 1 @Async：类上，说明整个类中的方法都是异步。必须写我们自己配置的线程池 —— ("myIoThreadPool")
 *  2 @Async：方法上，说明这个方法是异步。不用写我们自己配置的线程池
 * @author CC
 * @since 2023/5/24 0024
 */
@Service
@Async("myIoThreadPool")
public class AsyncServiceImpl implements IAsyncService {

    private static final Logger log = LoggerFactory.getLogger(AsyncServiceImpl.class);

    //类上写了@Async，这里就可以不写了。
    //可以不写 ("myIoThreadPool")。因为在IoThreadPool中开启了异步，说明异步用的就是我们配置的io线程池
    //如果类上面打了 @Async ，这里必须写：("myIoThreadPool")
    @Override
    //@Async
    public void async1(){
        //模仿io流耗时
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
        log.info("打印：{}", "异步方法1111！");
    }

    //@Async在类上面，说明这个方法也是异步方法。如果不打，无法开启异步。
    @Override
    public void async2(){
        //模仿io流耗时
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
        log.info("打印：{}", "异步方法2222！");
    }
}

    @Resource
    private IAsyncService asyncService;
    
    //开启异步1 —— @Async
    @Test
    public void test03() throws Exception {
        log.info("打印：{}", "异步测试的-主方法1");
        asyncService.async1();
        asyncService.async2();
        //不会等待异步方法执行，直接返回前端数据
        log.info("打印：{}", "异步测试的-主方法2");
    }

    @Resource(name = "myIoThreadPool")
    private ThreadPoolTaskExecutor myIoThreadPool;
    
    //开启异步2 —— CompletableFuture.runAsync()
    @Test
    public void test04() throws Exception {
        log.info("打印：{}", "异步测试的-主方法1");
        CompletableFuture.runAsync(() -> {
            log.info("打印：{}", "异步方法1！");
            //异步执行的代码，也可以是方法，该方法不用单独写到其他类中。
            this.async2("异步方法1！-end");
        }, myIoThreadPool);
        //不会等待异步方法执行，直接返回前端数据
        log.info("打印：{}", "异步测试的-主方法2");
    }

    //异步需要执行的方法，可以写在同一个类中。
    private void async2(String msg) {
        //模仿io流耗时
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
        log.info("打印：{}", msg);
    }