springboot 在程序入口初始化资源事例

背景：

项目中遇到这样一个问题，一个接口涉及到复杂运算（日环比，周同比，数据量大），前端查询相关报表统计信息时候，耗时两秒左右；现在考虑用map缓存查询结果；一种方法是：实现接口 CommandLineRunner，重写run方法，利用ScheduledExecutorService 线程池定时查询结果并保存在sevice中的map中，接口查询时候先走map；大致过程如下：

@Component
public class MyCommandLineRunner implements CommandLineRunner {

    private StatisticsTasker statisticsTasker;
    private static ScheduledExecutorService timer = newScheduledThreadPool(2);
    @Override
    public void run(String... args) throws Exception {
       this.statisticsTasker = new StatisticsTasker(ApplicationContextHelper.getContext().getBean(UserServiceImpl.class));
        timer.scheduleAtFixedRate(statisticsTasker,1000,2000, TimeUnit.MILLISECONDS);
    }
    
}

@Slf4j
@Data
@AllArgsConstructor
@NoArgsConstructor
public class StatisticsTasker implements Runnable {

    private  UserServiceImpl userServiceImpl;

    @Override
    public void run() {
        WalletStatisticsDTO walletStatistics = userServiceImpl.walletStatistics(true);
        userServiceImpl.statistics.put("walletStatistics",walletStatistics);
    }
}

ApplicationContextHelper是一个工具类：

/**
 * spring工厂调用辅助类
 * @author flyleft
 */
public class ApplicationContextHelper implements ApplicationContextAware {


    private static DefaultListableBeanFactory springFactory;

    private static ApplicationContext context;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
        context = applicationContext;
        if (applicationContext instanceof AbstractRefreshableApplicationContext) {
            AbstractRefreshableApplicationContext springContext =
                    (AbstractRefreshableApplicationContext) applicationContext;
            springFactory = (DefaultListableBeanFactory) springContext.getBeanFactory();
        } else if (applicationContext instanceof GenericApplicationContext) {
            GenericApplicationContext springContext = (GenericApplicationContext) applicationContext;
            springFactory = springContext.getDefaultListableBeanFactory();
        }
    }

    public static DefaultListableBeanFactory getSpringFactory() {
        return springFactory;
    }

    public static ApplicationContext getContext() {
        return context;
    }
}

这样，应用启动之后，定时任务会定时调用service的statistics接口，并将结果放入map当中；页面查询直接从map当中取数据；

二：考虑从程序入口，开启一个线程来执行初始化的逻辑：

public class SpringDemolication {

    public static void main(String[] args)
    {
        SpringApplication.run(SpringDemolication.class, args);
        triggerInit();
    }
    private static void triggeInit() {
        new Thread(() -> InitExecutor.doInit()).start();
    }
}

@Slf4j
public final class InitExecutor {
    private static AtomicBoolean initialized = new AtomicBoolean(false);
    private static ScheduledExecutorService timer = newScheduledThreadPool(2);

    public static void doInit() {
        if (initialized.compareAndSet(false, true)) {
            try {
                timer.scheduleAtFixedRate(new StatisticsTasker(ApplicationContextHelper.getContext().getBean(UserServiceImpl.class)), 1000, 2000, TimeUnit.MILLISECONDS);
            } catch (Exception e) {
                log.info("[InitExecutor] WARN: Initialization failed", e);
                e.printStackTrace();
            }
        }
    }
    private InitExecutor() {
    }

这样也可以执行初始化线程池，执行定时任务