springboot 注解@Async实现异步调用-蒲公英云

springboot 注解@Async实现异步调用

冷不防 2023-02-08 12:41 73阅读 0赞

文章目录

- - 1.模拟业务方法并添加注解@Async
  - 2.在启动类增加@EnableAsync注解
  - 3.测试类与接口一
  - 4.结果比较
  - 5.使用AsyncResult接收异步执行结果
  - 6.测试类与接口二
  - 7.总结

1.模拟业务方法并添加注解@Async

@Service
public class TaskService {
    private static final Random random = new Random();
    @Async
    public void task1() {
        System.out.println("run task1 start...");
        long start = System.currentTimeMillis();
        try {
            Thread.sleep(random.nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("run task1 end..., time: " + (System.currentTimeMillis() - start) + " ms");
    }
    @Async
    public void task2() {
        System.out.println("run task2 start...");
        long start = System.currentTimeMillis();
        try {
            Thread.sleep(random.nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("run task2 end..., time: " + (System.currentTimeMillis() - start) + " ms");
    }
    @Async
    public void task3() {
        System.out.println("run task3 start...");
        long start = System.currentTimeMillis();
        try {
            Thread.sleep(random.nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("run task3 end..., time: " + (System.currentTimeMillis() - start) + " ms");
    }
}

2.在启动类增加@EnableAsync注解

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

3.测试类与接口一

@RestController
public class TestAsyncController {
    @Autowired
    private TaskService taskService;
    @GetMapping("test/async/task")
    public void testAsyncTask() {
        long start = System.currentTimeMillis();
        taskService.task1();
        taskService.task2();
        taskService.task3();
        System.out.println("run all task end: " + (System.currentTimeMillis() - start) + " ms");
    }
}

4.结果比较

// task任务不加 @Async 的日志打印
run task1 start...
run task1 end..., time: 3739 ms
run task2 start...
run task2 end..., time: 8025 ms
run task3 start...
run task3 end..., time: 9057 ms
run all task end: 20821 ms
// task任务加 @Async 的日志打印 主任务先结束
run all task end: 4 ms
run task1 start...
run task2 start...
run task3 start...
run task3 end..., time: 1095 ms
run task2 end..., time: 4952 ms
run task1 end..., time: 8442 ms

5.使用AsyncResult接收异步执行结果

@Service
public class TaskService {
    private static final Random random = new Random();
    @Async
    public Future<String> task1() {
        System.out.println("run task1 start...");
        long start = System.currentTimeMillis();
        try {
            Thread.sleep(random.nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("run task1 end..., time: " + (System.currentTimeMillis() - start) + " ms");
        return new AsyncResult<>("task1 result");
    }
    @Async
    public Future<String> task2() {
        System.out.println("run task2 start...");
        long start = System.currentTimeMillis();
        try {
            Thread.sleep(random.nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("run task2 end..., time: " + (System.currentTimeMillis() - start) + " ms");
        return new AsyncResult<>("task2 result");
    }
    @Async
    public Future<String> task3() {
        System.out.println("run task3 start...");
        long start = System.currentTimeMillis();
        try {
            Thread.sleep(random.nextInt(10000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("run task3 end..., time: " + (System.currentTimeMillis() - start) + " ms");
        return new AsyncResult<>("task3 result");
    }
}

6.测试类与接口二

@RestController
public class TestAsyncController {
    @Autowired
    private TaskService taskService;
    @GetMapping("test/async/task")
    public void testAsyncTask() {
        long start = System.currentTimeMillis();
        Future<String> future1 = taskService.task1();
        Future<String> future2 = taskService.task2();
        Future<String> future3 = taskService.task3();
        while (true) {
            if (future1.isDone() && future2.isDone() && future3.isDone()) {
                System.out.println(future1.get());
                System.out.println(future2.get());
                System.out.println(future3.get());
                break;
            }
            TimeUnit.MICROSECONDS.sleep(500);
        }
        System.out.println("run all task end: " + (System.currentTimeMillis() - start) + " ms");
    }
}

7.总结

使用@Async注解的方法task1 task2 task3是异步调用的
使用@Async在主任务先结束，但主任务需要获取task1 task2 task3的执行结果的场景中不适用，需要配合AsyncResult实现(查看AsyncResult的源码，会发现它实现了Future<T>)
@Async所修饰的函数不要定义为static类型，这样异步调用不会生效