关于spring session redis共享session的跨子域的处理

安装完redis, spring端只要下面这两个bean配置上就可以用了

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
<bean class="org.springframework.session.data.redis.config.annotation.web.http.RedisHttpSessionConfiguration"/>

<bean id="jedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory">
    <property name="port" value="${redis_port}" />
    <property name="hostName" value="${redis_url}" />
</bean>

官方示例都是零配置的写法，画风变的太大以至于在AbstractHttpSessionApplicationInitializer这里浪费了 很久。其实用上面这种方式，是完全不需要再写AbstractHttpSessionApplicationInitializer的，他们干的是一件 事。

关于子域的坑

发现spring session在获取sessionid时，在CookieHttpSessionStrategy中并没有做跨子域的处理...

 private Cookie createSessionCookie(HttpServletRequest request,
            Map<String, String> sessionIds) {
        Cookie sessionCookie = new Cookie(cookieName,"");
        if(isServlet3Plus) {
            sessionCookie.setHttpOnly(true);
        }
        sessionCookie.setSecure(request.isSecure());
        sessionCookie.setPath(cookiePath(request));
        // TODO set domain?
        ...

    private static String cookiePath(HttpServletRequest request) {
        return request.getContextPath() + "/";
    }

其实这里只要把cookiePath的返回值设置为统一的根路径就能让session id从根域获取了，这样同根下的所有web应用就可以轻松实现单点登录共享session了。既然找到了问题，解决就容易多了，下面列几种解决方案：

1. 改spring session源码，并重新打包
2. 代码复用CookieHttpSessionStrategy，改cookiePath，并在spring注入时指定自己写的这份Strategy

搭建spring session源码的开发环境太麻烦了，我用的方案2

private static String cookiePath(HttpServletRequest request) {
    return "/";
}

并在spring redis中加入如下配置

<bean id="redisRepository" class="org.springframework.session.data.redis.RedisOperationsSessionRepository">
        <constructor-arg ref="jedisConnectionFactory" />
</bean>
<bean id="cookieHttpSessionStrategy" class="reyo.sdk.utils.spring.CookieHttpSessionStrategy"/>
<bean class="org.springframework.session.web.http.SessionRepositoryFilter">
    <constructor-arg ref="redisRepository" />
    <property name="httpSessionStrategy" ref="cookieHttpSessionStrategy"/>
</bean>

搞定(spring 4.3.0不支持)