spring 学习1-Request, session, and global session scopes|（Initial web configuration）

最新推荐文章于 2022-07-30 02:05:14 发布

翻译最新推荐文章于 2022-07-30 02:05:14 发布 · 614 阅读

本文详细解释了如何在Spring Web MVC环境中配置作用域为请求、会话和全局会话级别的bean，以及如何在使用不同Servlet环境时进行初始化设置。包括使用RequestContextListener和RequestContextFilter的方法，确保在非DispatcherServlet处理请求时仍能访问到所需bean。

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Initial web configuration

To support the scoping of beans at the request, session, and global session levels (web-scoped beans), some minor initial configuration is required before you define your beans. (This initial setup is not required for the standard scopes, singleton and prototype.)

How you accomplish this initial setup depends on your particular Servlet environment..

If you access scoped beans within Spring Web MVC, in effect, within a request that is processed by the Spring DispatcherServlet, or DispatcherPortlet, then no special setup is necessary: DispatcherServlet and DispatcherPortlet already expose all relevant state.

If you use a Servlet 2.5 web container, with requests processed outside of Spring’s DispatcherServlet (for example, when using JSF or Struts), you need to register theorg.springframework.web.context.request.RequestContextListener ServletRequestListener. For Servlet 3.0+, this can done programmatically via theWebApplicationInitializer interface. Alternatively, or for older containers, add the following declaration to your web application’s web.xml file:

<web-app>
    ...
    <listener>
        <listener-class>
            org.springframework.web.context.request.RequestContextListener
        </listener-class>
    </listener>
    ...
</web-app>

Alternatively, if there are issues with your listener setup, consider the provided RequestContextFilter. The filter mapping depends on the surrounding web application configuration, so you have to change it as appropriate.

<web-app>
    ...
    <filter>
        <filter-name>requestContextFilter</filter-name>
        <filter-class>org.springframework.web.filter.RequestContextFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>requestContextFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    ...
</web-app>

DispatcherServlet, RequestContextListener and RequestContextFilter all do exactly the same thing, namely bind the HTTP request object to the Thread that is servicing that request. This makes beans that are request- and session-scoped available further down the call chain.