异步请求:DeferredResult和Callable-蒲公英云

异步请求:DeferredResult和Callable

示例代码如下

package com.atguigu.controller;
import java.util.UUID;
import java.util.concurrent.Callable;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.context.request.async.DeferredResult;
import com.atguigu.service.DeferredResultQueue;
@Controller
public class AsyncController {
    @ResponseBody
    @RequestMapping("/createOrder")
    public DeferredResult<Object> createOrder(){
        DeferredResult<Object> deferredResult = new DeferredResult<>((long)3000, "create fail...");
        DeferredResultQueue.save(deferredResult);
        return deferredResult;
    }
    @ResponseBody
    @RequestMapping("/create")
    public String create(){
        //创建订单
        String order = UUID.randomUUID().toString();
        DeferredResult<Object> deferredResult = DeferredResultQueue.get();
        deferredResult.setResult(order);
        return "success===>"+order;
    }
    /**
     * 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）。
     * 
     * preHandle.../springmvc-annotation/async01
        主线程开始...Thread[http-bio-8081-exec-3,5,main]==>1513932494700
        主线程结束...Thread[http-bio-8081-exec-3,5,main]==>1513932494700
        =========DispatcherServlet及所有的Filter退出线程============================
        ================等待Callable执行==========
        副线程开始...Thread[MvcAsync1,5,main]==>1513932494707
        副线程开始...Thread[MvcAsync1,5,main]==>1513932496708
        ================Callable执行完成==========
        ================再次收到之前重发过来的请求========
        preHandle.../springmvc-annotation/async01
        postHandle...（Callable的之前的返回值就是目标方法的返回值）
        afterCompletion...
        异步的拦截器:
            1）、原生API的AsyncListener
            2）、SpringMVC：实现AsyncHandlerInterceptor；
     * @return
     */
    @ResponseBody
    @RequestMapping("/async01")
    public Callable<String> async01(){
        System.out.println("主线程开始..."+Thread.currentThread()+"==>"+System.currentTimeMillis());
        Callable<String> callable = new Callable<String>() {
            @Override
            public String call() throws Exception {
                System.out.println("副线程开始..."+Thread.currentThread()+"==>"+System.currentTimeMillis());
                Thread.sleep(2000);
                System.out.println("副线程开始..."+Thread.currentThread()+"==>"+System.currentTimeMillis());
                return "Callable<String> async01()";
            }
        };
        System.out.println("主线程结束..."+Thread.currentThread()+"==>"+System.currentTimeMillis());
        return callable;
    }
}