SpringMVC-异步功能

假设某个请求需要耗费大量的时间,那么,该请求的线程就会一直同步等待该次请求完成,才能被返回线程池,分配给下一个新的请求，这样极大的限制了系统的处理能力.所以我们希望能在controller层的方法中异步执行,另起一个线程去处理耗时任务,让该线程先返回线程池,那么它就可以继续处理下一个请求,从而增加web程序的吞吐量.

得先确保你用的是Servlet 3.0及以上的版本,Spring MVC版本是4以上
确保web.xml中的中添加：

<filter>
        <filter-name>characterEncodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <async-supported>true</async-supported>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>characterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <servlet>
        <servlet-name>app</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring/spring-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
        <async-supported>true</async-supported>
    </servlet>

3 代码
3.1使用DeferredResult

private final int CorePoolSize = 4;
private ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(CorePoolSize);

@RequestMapping(value="/asynctask", method = RequestMethod.GET)
    public DeferredResult<ModelAndView> asyncTask(){
        final DeferredResult<ModelAndView> deferredResult = new DeferredResult<ModelAndView>();
        scheduler.schedule(new Runnable() {
            @Override
            public void run() {
                try {
                    ModelAndView mav = new ModelAndView("testView");
                    mav.addObject("result", "jkluio");
                    deferredResult.setResult(mav);
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        }, 5, TimeUnit.SECONDS);

        return deferredResult;
    }

3.2 使用WebAsyncTask

@RequestMapping(value="/asynctask1", method = RequestMethod.GET)
    public WebAsyncTask asynctask1(){
        Callable<ModelAndView> callable = new Callable<ModelAndView>() {
            public ModelAndView call() throws Exception {
                Thread.sleep(3000); 
                ModelAndView mav = new ModelAndView("testView");
                mav.addObject("result", "执行成功");
                return mav;
            }
        };
        return new WebAsyncTask(callable);

4 新建testView.jsp承接后台返回内容

猜你喜欢