servlet3.0开始支持异步请求,springmvc3.2引入支持异步http。相比于servlet2.5,异步后的程序在系统性能,尤其是吞吐量,资源利用率都能得到极大的提高。下图摘自网友文档(http://www.cnblogs.com/guogangj/p/5457959.html),比较能清晰展示性能之所以提高的原因。
servlet3.0可以不需要web.xml,但不是说必须不能有,就好像spring使用注解一样,xml和注解不冲突。
使用springmvc的异步,首先修改web.xml,使其版本为3.0,然后在所有filter和servlet标签下加上一句<async-supported>true</async-supported>,注意是所有的都要加,否则执行时会报错
<?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"
id="app_id" version="3.0">
<display-name>app_id</display-name>
<welcome-file-list>
<welcome-file>login.jsp</welcome-file>
</welcome-file-list>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<listener>
<listener-class>net.bull.javamelody.SessionListener</listener-class>
</listener>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:config/spring-core.xml</param-value>
</context-param>
<servlet>
<servlet-name>spring-mvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:config/spring-mvc.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
<async-supported>true</async-supported>
</servlet>
<servlet-mapping>
<servlet-name>spring-mvc</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
<session-config>
<session-timeout>60</session-timeout>
</session-config>
</web-app>
spring和springmvc的配置文件都不需要进行额外的配置,需要修改的是controller所有的方法返回值要么为Callable<V>,要么WebAsyncTask<V>,以下是示例
@RequestMapping("turnFunction.do")
public WebAsyncTask<ModelAndView> turnFunction() {
return new WebAsyncTask<>(() -> {
return new ModelAndView("system/function/functionlist");
});
}