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spring boot项目

【注意】

1. 不能在类内部 (bean内部，spring无法感知) 调用@Async (就是要)，spring无法感知到，所以不会再子线程执行
   @Async生效需要一个bean(controller)调用另一个bean(service)的方法
2. 如果有返回值，返回值是Future类型的包装

//controller.java    @Autowired    private FakeService fakeService;    @GetMapping("/slow")    public String slow() {        StopWatch watch = new StopWatch("my watch");        //通常模式service调用        watch.start("slowServiceNormal");        fakeService.slowService();        fakeService.slowService();        watch.stop();        //异步模式,在子线程各自独立调用service，有返回值        watch.start("slowService async with return");        Future
   
     res1 = fakeService.slowServiceAsync();        Future
    
      res2 = fakeService.slowServiceAsync();        try {            res1.get();            res2.get();        } catch (InterruptedException e) {            e.printStackTrace();        } catch (ExecutionException e) {            e.printStackTrace();        }        watch.stop();        //无返回值调用，直接返回，子线程继续工作        watch.start("slowServiceNoReturn");        fakeService.slowServiceNoReturn();        fakeService.slowServiceNoReturn();        watch.stop();        System.out.println(watch.prettyPrint());        return "done";    }
    
   

package boottest;import org.springframework.scheduling.annotation.Async;import org.springframework.scheduling.annotation.AsyncResult;import org.springframework.scheduling.annotation.EnableAsync;import org.springframework.stereotype.Service;import java.util.concurrent.Future;import java.util.concurrent.TimeUnit;import java.util.concurrent.locks.LockSupport;/** * @author zhanghui * @date 2019/5/9 */@Service@EnableAsyncpublic class FakeService {    public long slowService(){        System.out.println("slowServiceNormal");        LockSupport.parkNanos(TimeUnit.SECONDS.toNanos(5));        System.out.println("slowServiceNormal done");        return 5;    }    //异步调用，有返回值，必须是Future类型，不然报错    @Async    public Future
   
     slowServiceAsync(){        System.out.println("slowServiceAsync");        return new AsyncResult(slowService());    }    @Async    public void slowServiceNoReturn(){        System.out.println("slowServiceNoReturn");        slowService();    }}
   

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