热乎乎的面经：Spring中Scheduled和Async两种调度方式有啥区别？

@EnableScheduling
@EnableAsync
public class WebAppConfig {
   ....
｝

public final static long ONE_DAY = 24 * 60 * 60 * 1000;
public final static long ONE_HOUR = 60 * 60 * 1000;
 
@Scheduled(fixedRate = ONE_DAY)
public void scheduledTask() {
   System.out.println(" 我是一个每隔一天就会执行一次的调度任务");
}
 
@Scheduled(fixedDelay = ONE_HOURS)
public void scheduleTask2() {
    System.out.println(" 我是一个执行完后，隔一小时就会执行的任务");
}
 
@Scheduled(initialDelay=1000, fixedRate=5000)
public void doSomething() {
    // something that should execute periodically
}
 
@Scheduled(cron = "0 0/1 * * * ? ")
public void ScheduledTask3() {
    System.out.println(" 我是一个每隔一分钟就就会执行的任务");
}

public void AsyncTask(){
    @Async
    public void doSomeHeavyBackgroundTask(int sleepTime) {
        try {
            Thread.sleep(sleepTime);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    @Async
    public Future<String> doSomeHeavyBackgroundTask() {
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return null;
    }
     
    public void printLog() {
         System.out.println(" i print a log ,time=" + System.currentTimeMillis());
    }
 
}

@RunWith(SpringJUnit4ClassRunner.class)
@WebAppConfiguration
@ContextConfiguration(classes = AsycnTaskConfig.class) //要声明@EnableASync
public class AsyncTaskTest {
    @Autowired
    AsyncTask asyncTask;
    @Test
    public void AsyncTaskTest() throws InterruptedException {
        if (asyncTask != null) {
            asyncTask.doSomeHeavyBackgroundTask(4000);
            asyncTask.printLog();
            Thread.sleep(5000);
        }
    }
}

public void AsyncTask(){
    public void fakeAsyncTaskTest(){
        doSomeHeavyBackgroundTask(4000);
        printLog();
        //你会发现，当你像这样内部调用的时候，居然是同步执行的，不是异步的！！
    }
     
    @Async
    public void doSomeHeavyBackgroundTask(int sleepTime) {
        try {
            Thread.sleep(sleepTime);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
     
    public void printLog() {
        System.out.println(" i print a log ");
    }
}

public class MyAsyncUncaughtExceptionHandler implements AsyncUncaughtExceptionHandler {
    @Override
    public void handleUncaughtException(Throwable ex, Method method, Object... params) {
        // handle exception
    }
}

@Configuration
@EnableAsync
public class AsyncConfig implements AsyncConfigurer {
    @Bean
    public AsyncTask asyncBean() {
        return new AsyncTask();
    }
     
    @Override
    public Executor getAsyncExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(7);
        executor.setMaxPoolSize(42);
        executor.setQueueCapacity(11);
        executor.setThreadNamePrefix("MyExecutor-");
        executor.initialize();
        return executor;
    }
     
    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
         return new MyAsyncUncaughtExceptionHandler();
    }
}