Async support must be enabled on a servlet and for all filters involved in async request processing

一、报错日志
java.lang.IllegalStateException: Async support must be enabled on a servlet and for all filters involved in async request processing. This is done in Java code using the Servlet API or by adding "<async-supported>true</async-supported>" to servlet and filter declarations in web.xml.

二、解决办法
 
1、修改web.xml头部信息，是因为<async-supported>true</async-supported>是web.xml 3.0的新特性，所以更改web.xml头部文件如下即可，如果是跳过：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         version="3.0">

2、添加<async-supported>true</async-supported> 

在web.xml中对DispatcherServlet和所有filter添加 ：<async-supported>true</async-supported> 

3、如果集成了shiro一定要注意在mapping中增加dispatcher项，否则会抛org.apache.shiro.UnavailableSecurityManagerException异常 

<filter-mapping>
<filter-name>shiroFilter</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>ASYNC</dispatcher>
</filter-mapping>
4、测试代码

@RequestMapping("callable")
@ResponseBody
public Callable<String> callable() {
    Callable<String> callable = new Callable<String>() {
        public String call() throws Exception {
            System.out.println("异步开始：" + System.currentTimeMillis());
            Thread.sleep(5000);
            System.out.println("异步结束：" + System.currentTimeMillis());
            return System.currentTimeMillis() +"";
        }
    };
    System.out.println("主线程开始：" + System.currentTimeMillis());
    return callable;
}