60、springmvc-异步请求-返回Callable

60、springmvc-异步请求-返回Callable

@Controller
public class AsyncController { @RequestMapping("async01")
@ResponseBody
public Callable<String> async01() { System.out.println("主线程开始..." + Thread.currentThread() + "===》" + System.currentTimeMillis());
Callable<String> callable = new Callable<String>() {
public String call() throws Exception {
System.out.println("子线程开始..." + Thread.currentThread() + "===》" + System.currentTimeMillis());
Thread.sleep(3000);
System.out.println("子线程结束..." + Thread.currentThread() + "===》" + System.currentTimeMillis());
return "Callable<String> async01()";
}
};
System.out.println("主线程结束..." + Thread.currentThread() + "===》" + System.currentTimeMillis());
return callable;
}
}

60.1 Spring MVC异步执行

1. 控制器返回Callable
2. Spring异步处理，将Callable 提交到 TaskExecutor 使用一个隔离的线程进行执行
3. DispatcherServlet和所有的Filter退出web容器的线程，但是response 保持打开状态；
4. Callable返回结果，SpringMVC将请求重新派发给容器，恢复之前的处理；
5. 根据Callable返回的结果。SpringMVC继续进行视图渲染流程等（从收请求-视图渲染）。

60.2 运行结果

60.3 异步拦截器

1. 原生API的AsyncListener
2. SpringMVC：实现AsyncHandlerInterceptor；

60.4 注意警告。

• 查看执行类源码 org.springframework.web.context.request.async.WebAsyncManager 有这么一段获取
• 如果没有指定 AsyncTaskExecutor 就会 warning 警告 logExecutorWarning();

AsyncTaskExecutor executor = webAsyncTask.getExecutor();
if (executor != null) {
this.taskExecutor = executor;
}
else {
logExecutorWarning();
}

• 解决：我们可以自己配置一个线程池来执行，如下
• 通过在AppConfig implements WebMvcConfigurer 中 configurer.setTaskExecutor(threadPoolTaskExecutor());来执行

/**
* 自定义 异步任务执行线程池，解决warnning警告
* @return
*/
@Bean
public ThreadPoolTaskExecutor threadPoolTaskExecutor() {
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
executor.initialize();
executor.setCorePoolSize(10);
executor.setMaxPoolSize(50);
executor.setThreadNamePrefix("JHW");
return executor;
}@Bean
public TimeoutCallableProcessingInterceptor timeoutCallableProcessingInterceptor() {
return new TimeoutCallableProcessingInterceptor();
}public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
configurer.setTaskExecutor(threadPoolTaskExecutor());
configurer.setDefaultTimeout(60 * 1000L);
configurer.registerCallableInterceptors(timeoutCallableProcessingInterceptor());
}