SpringBoot异步处理的四种实现方式

@RequestMapping("/async")
public void async(HttpServletRequest request) {
    AsyncContext asyncContext = request.getAsyncContext();
}

public interface AsyncContext {

    ServletRequest getRequest();

    ServletResponse getResponse();

    void addListener(AsyncListener var1);

    void setTimeout(long var1);

    // 省略其他方法
}

public interface AsyncListener extends EventListener {
    // 异步执行完毕时调用
    void onComplete(AsyncEvent var1) throws ioException;
    // 异步线程执行超时调用
    void onTimeout(AsyncEvent var1) throws IOException;
    // 异步线程出错时调用
    void onError(AsyncEvent var1) throws IOException;
    // 异步线程开始时调用
    void onStartAsync(AsyncEvent var1) throws IOException;
}

@GetMapping(value = "/email/send")
public void servletReq(HttpServletRequest request) {
    AsyncContext asyncContext = request.startAsync();
    // 设置监听器:可设置其开始、完成、异常、超时等事件的回调处理
    asyncContext.addListener(new AsyncListener() {
        @Override
        public void onTimeout(AsyncEvent event) {
            System.out.println("处理超时了...");
        }

        @Override
        public void onStartAsync(AsyncEvent event) {
            System.out.println("线程开始执行");
        }

        @Override
        public void onError(AsyncEvent event) {
            System.out.println("执行过程中发生错误：" + event.getThrowable().getMessage());
        }

        @Override
        public void onComplete(AsyncEvent event) {
            System.out.println("执行完成，释放资源");
        }
    });
    //设置超时时间
    asyncContext.setTimeout(6000);
    asyncContext.start(new Runnable() {
        @Override
        public void run() {
            try {
                Thread.sleep(5000);
                System.out.println("内部线程：" + Thread.currentThread().getName());
                asyncContext.getResponse().getWriter().println("async processing");
            } catch (Exception e) {
                System.out.println("异步处理发生异常：" + e.getMessage());
            }
            // 异步请求完成通知，整个请求完成
            asyncContext.complete();
        }
    });
    //此时request的线程连接已经释放了
    System.out.println("主线程：" + Thread.currentThread().getName());
}

@GetMapping("/email")
public Callable<String> order() {
    System.out.println("主线程开始：" + Thread.currentThread().getName());
    Callable<String> result = () -> {
        System.out.println("副线程开始：" + Thread.currentThread().getName());
        Thread.sleep(1000);
        System.out.println("副线程返回：" + Thread.currentThread().getName());
        return "success";
    };

    System.out.println("主线程返回：" + Thread.currentThread().getName());
    return result;
}

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Resource
    private ThreadPoolTaskExecutor myThreadPoolTaskExecutor;

    
    @Bean(name = "asyncPoolTaskExecutor")
    public ThreadPoolTaskExecutor getAsyncThreadPoolTaskExecutor() {
        ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
        taskExecutor.setCorePoolSize(2);
        taskExecutor.setMaxPoolSize(10);
        taskExecutor.setQueueCapacity(25);
        taskExecutor.seTKEepAliveSeconds(200);
        taskExecutor.setThreadNamePrefix("thread-pool-");
        // 线程池对拒绝任务（无线程可用）的处理策略，目前只支持AbortPolicy、CallerRunsPolicy；默认为后者
        taskExecutor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        taskExecutor.initialize();
        return taskExecutor;
    }

    @Override
    public void configureAsyncSupport(final AsyncSupportConfigurer configurer) {
        // 处理callable超时
        configurer.setDefaultTimeout(60 * 1000);
        configurer.setTaskExecutor(myThreadPoolTaskExecutor);
        configurer.reGISterCallableInterceptors(timeoutCallableProcessingInterceptor());
    }

    @Bean
    public TimeoutCallableProcessingInterceptor timeoutCallableProcessingInterceptor() {
        return new TimeoutCallableProcessingInterceptor();
    }
}

@GetMapping("/webAsyncTask")
public WebAsyncTask<String> webAsyncTask() {
    log.info("外部线程：" + Thread.currentThread().getName());
    WebAsyncTask<String> result = new WebAsyncTask<>(60 * 1000L, new Callable<String>() {
        @Override
        public String call() {
            log.info("内部线程：" + Thread.currentThread().getName());
            return "success";
        }
    });
    result.onTimeout(new Callable<String>() {
        @Override
        public String call() {
            log.info("timeout callback");
            return "timeout callback";
        }
    });
    result.onCompletion(new Runnable() {
        @Override
        public void run() {
            log.info("finish callback");
        }
    });
    return result;
}

@RequestMapping("/quotes")
@ResponseBody
public DeferredResult<String> quotes() {
  DeferredResult<String> deferredResult = new DeferredResult<String>();
  // Save the deferredResult in in-memory queue ...
  return deferredResult;
}

// In some other thread...
deferredResult.setResult(data);

@Controller
@RequestMapping("/async/controller")
public class AsyncHelloController {

    private List<DeferredResult<String>> deferredResultList = new ArrayList<>();

    @ResponseBody
    @GetMapping("/hello")
    public DeferredResult<String> helloGet() throws Exception {
        DeferredResult<String> deferredResult = new DeferredResult<>();

        //先存起来，等待触发
        deferredResultList.add(deferredResult);
        return deferredResult;
    }

    @ResponseBody
    @GetMapping("/setHelloToAll")
    public void helloSet() throws Exception {
        // 让所有hold住的请求给与响应
        deferredResultList.forEach(d -> d.setResult("say hello to all"));
    }
}

@SpringBootApplication
@EnableAsync
public class App {

    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}

@Service
public class SyncService {

    @Async
    public void asyncEvent() {
        // 业务处理
    }
}

@RestController
public class IndexController {

    @Resource
    private UserService userService;

    @RequestMapping("/async")
    public String async(){
        System.out.println("--IndexController--1");
        userService.sendSms();
        System.out.println("--IndexController--4");
        return "success";
    }
}

@Service
public class UserService {

    @Async
    public void sendSms(){
        System.out.println("--sendSms--2");
        IntStream.range(0, 5).forEach(d -> {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        });
        System.out.println("--sendSms--3");
    }
}

// 普通方法
public String aMethod(){
}

// 对照Callable方法
public Callable<String>  aMethod(){
}