1.定时任务schedule

• springboot使用注解方式开启定时任务

  • 启动类加上@EnableScheduling开启定时任务自动扫描
  • 定时任务业务类加注解@Component被容器扫描
  • 定时执行的方法加上注解@Scheduled(fixedRate = 10000)

• 定时规则

  • @Scheduled(cron = “* * * * * *”)：定时任务表达式，分别表示秒分时日月周
  • @Scheduled(fixedRate = 1000)：定时1秒执行一次
  • @Scheduled(fixedDelay = 1000)：上一次代码执行结束后1秒再执行；假如代码需要执行1秒，也就是说每2秒执行一次

• 代码示例

  package com.gen.schedule;import org.springframework.scheduling.annotation.Scheduled;
  import org.springframework.stereotype.Component;import java.time.LocalDateTime;@Component
  public class CustomSchedule {@Scheduled(cron = "* * * * * *")public void testSchedule() {System.out.println(LocalDateTime.now());}}
  

2.异步任务

• springboot使用注解方式开启异步任务

  • 启动类加上@EnableAsync注解开启功能自动扫描
  • 定义异步任务类并使用@Component被容器扫描，异步方法加上@Async
  • 如果需要异步类返回结果，增加Future返回结果AsyncResult，调用处拿返回结果时，判断是否完成isDone()

• 代码示例

  • 异步类

    package com.gen.async;import org.springframework.scheduling.annotation.Async;
    import org.springframework.scheduling.annotation.AsyncResult;
    import org.springframework.stereotype.Component;import java.util.concurrent.Future;@Component
    public class CustomAsync {@Asyncpublic void test1() {try {Thread.sleep(1000L);System.out.println("异步任务test1");} catch (InterruptedException e) {e.printStackTrace();}}@Asyncpublic Future<String> test2() {try {Thread.sleep(2000L);System.out.println("异步任务test2");} catch (InterruptedException e) {e.printStackTrace();}return new AsyncResult("任务返回值");}}
    

  • controller调用

    @Autowired
    private CustomAsync customAsync;@GetMapping("test")
    public void test() {this.customAsync.test1();Future<String> stringFuture = this.customAsync.test2();while (true) {if (stringFuture.isDone()) {try {System.out.println(stringFuture.get());} catch (Exception e) {e.printStackTrace();} finally {break;}}}
    }