Spring用new创建对象，之前的注解会失效

这是由于注入的对象在Spring启动时就创建成功了，注解也在那时就生效了，当重新new的时候，会重新分配空间和指针，成为了一个新的对象，之前的注解自然就失效了。

@Component
public class Tasks {
    private Logger logger = LoggerFactory.getLogger(getClass());
    @Async("thread_pool")
    public void task(){
        try {
            Thread.sleep(2000);
        } catch (Exception e) {
            logger.info(e.getMessage());
        } finally {
            logger.info(Thread.currentThread().getName() + " : hello world");
        }
    }
}
@Configuration
@EnableAsync
public class MyThreadPool {

    @Bean(name = "thread_pool")
    public TaskExecutor initThreadPool() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(16);
        executor.setMaxPoolSize(32);
        executor.setKeepAliveSeconds(2);
        executor.setThreadNamePrefix("thread-");
        executor.setQueueCapacity(64);
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        executor.setWaitForTasksToCompleteOnShutdown(true);
        return executor;
    }
}

@SpringBootApplication
public class Application implements CommandLineRunner {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Autowired
    private Tasks tasks;//正确
    //private Tasks tasks = new Tasks();//错误，@Component和@Async均不起作用

    @Override
    public void run(String... args) {
        for(int i = 0; i < 100; i++) {
            tasks.task();
        }
    }
}