先写些废话
新公司项目是有用到redis,之前老公司使用的缓存框架是ehcache.我redis并不熟悉.看过介绍以后知道是个nosql..既然是个数据库,那我想操作方法和jdbc操作关系数据库应该差不多吧..百度了一些例子以后发现确实差不多...比如注入一个spring的template以后使用template就行了. 比如:
很好理解,使用也蛮简单..就像jdbcTemplate...
一次偶然的调试,我发现了一个有趣的地方(公司用的是自己的框架,封装了springboot...所以启动默认配置了什么bean,很难看出来...)...
我记得session在tomcat启动服务器的时候好像是XXXSessionFacade..这里却是和Redis相关的一个实现类..然后向这个session存进去的东西再redis里也可以找到.
这说明这个session数据存取都是向redis去操作的.
看来一下maven的POM文件发现公司的项目依赖于srping-session-data-redis这个框架.
Spring整合SpringSession
实验了一下,发现其实spring只要额外配置2个bean就可以集成springsession了.
<context:annotation-config /> <bean class="org.springframework.session.data.redis.config.annotation.web.http.RedisHttpSessionConfiguration"> </bean> <bean id="jedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"> <property name="hostName" value="10.86.87.173" /> <property name="password" value="mesRedis+)" /> </bean>
稍微研究了下发现JedisConnectionFactory这个bean就是配置了Spring怎么通过jedis去连接redis服务器.
RedisHttpSessionConfiguration这个bean是真正和session相关的,它本身类上有注解@Configuration和@EnableScheduling.
@Configuration配合它方法上的@Bean可以配置一些其他的bean,比如SessionRepositoryFilter 就配置了一个bean,对应web.xmlXML里配置的那个filter...
@EnableScheduling这个注解我没用过,估计是要定时做一些事情,比如session过期了要去redis删除数据吧(但是redis好像也有超时删除数据的功能,为啥还要这么做呢..redis和Springsession都是第一次用,不太了解)..
除了上面2个bean,只要在web.xml里配置一个filter就行了.
1 <filter> 2 <filter-name>springSessionRepositoryFilter</filter-name> 3 <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> 4 </filter> 5 <filter-mapping> 6 <filter-name>springSessionRepositoryFilter</filter-name> 7 <url-pattern>/*</url-pattern> 8 </filter-mapping>
原理
因为第一次用,很多代码都没看过,所以不一定对.我觉得原理是这样的:
1.RedisHttpSessionConfiguration里会配置一个filter
@Bean public <S extends ExpiringSession> SessionRepositoryFilter<? extends ExpiringSession> springSessionRepositoryFilter(SessionRepository<S> sessionRepository, ServletContext servletContext) { SessionRepositoryFilter<S> sessionRepositoryFilter = new SessionRepositoryFilter<S>(sessionRepository); sessionRepositoryFilter.setServletContext(servletContext); if(httpSessionStrategy != null) { sessionRepositoryFilter.setHttpSessionStrategy(httpSessionStrategy); } return sessionRepositoryFilter; }
注入一个sessionRepository.这个repository其实就是redis的repository.只是哪里生成的我并不知道...
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { request.setAttribute(SESSION_REPOSITORY_ATTR, sessionRepository); SessionRepositoryRequestWrapper wrappedRequest = new SessionRepositoryRequestWrapper(request, response, servletContext); SessionRepositoryResponseWrapper wrappedResponse = new SessionRepositoryResponseWrapper(wrappedRequest,response); HttpServletRequest strategyRequest = httpSessionStrategy.wrapRequest(wrappedRequest, wrappedResponse); HttpServletResponse strategyResponse = httpSessionStrategy.wrapResponse(wrappedRequest, wrappedResponse); try { filterChain.doFilter(strategyRequest, strategyResponse); } finally { wrappedRequest.commitSession(); } }
这个filter会把request和response外面包装一层,就是装饰着模式.当调用request的getSession的时候
@Override public HttpSession getSession(boolean create) { HttpSessionWrapper currentSession = getCurrentSession(); if(currentSession != null) { return currentSession; } String requestedSessionId = getRequestedSessionId(); if(requestedSessionId != null) { S session = sessionRepository.getSession(requestedSessionId); if(session != null) { this.requestedSessionIdValid = true; currentSession = new HttpSessionWrapper(session, getServletContext()); currentSession.setNew(false); setCurrentSession(currentSession); return currentSession; } } if(!create) { return null; } S session = sessionRepository.createSession(); currentSession = new HttpSessionWrapper(session, getServletContext()); setCurrentSession(currentSession); return currentSession; }
其实是从sessionRepository里去拿session的.所以我们使用的HttpSession的实现类应该是 HttpSessionWrapper 里面包裹着 RedisSession.
1 private RedisSession getSession(String id, boolean allowExpired) { 2 Map<Object, Object> entries = getSessionBoundHashOperations(id).entries(); 3 if(entries.isEmpty()) { 4 return null; 5 } 6 MapSession loaded = new MapSession(); 7 loaded.setId(id); 8 for(Map.Entry<Object,Object> entry : entries.entrySet()) { 9 String key = (String) entry.getKey(); 10 if(CREATION_TIME_ATTR.equals(key)) { 11 loaded.setCreationTime((Long) entry.getValue()); 12 } else if(MAX_INACTIVE_ATTR.equals(key)) { 13 loaded.setMaxInactiveIntervalInSeconds((Integer) entry.getValue()); 14 } else if(LAST_ACCESSED_ATTR.equals(key)) { 15 loaded.setLastAccessedTime((Long) entry.getValue()); 16 } else if(key.startsWith(SESSION_ATTR_PREFIX)) { 17 loaded.setAttribute(key.substring(SESSION_ATTR_PREFIX.length()), entry.getValue()); 18 } 19 } 20 if(!allowExpired && loaded.isExpired()) { 21 return null; 22 } 23 RedisSession result = new RedisSession(loaded); 24 result.originalLastAccessTime = loaded.getLastAccessedTime() + TimeUnit.SECONDS.toMillis(loaded.getMaxInactiveIntervalInSeconds()); 25 result.setLastAccessedTime(System.currentTimeMillis()); 26 return result; 27 }
1 @Override 2 public HttpSession getSession(boolean create) { 3 HttpSessionWrapper currentSession = getCurrentSession(); 4 if(currentSession != null) { 5 return currentSession; 6 } 7 String requestedSessionId = getRequestedSessionId(); 8 if(requestedSessionId != null) { 9 S session = sessionRepository.getSession(requestedSessionId); 10 if(session != null) { 11 this.requestedSessionIdValid = true; 12 currentSession = new HttpSessionWrapper(session, getServletContext()); 13 currentSession.setNew(false); 14 setCurrentSession(currentSession); 15 return currentSession; 16 } 17 } 18 if(!create) { 19 return null; 20 } 21 S session = sessionRepository.createSession(); 22 currentSession = new HttpSessionWrapper(session, getServletContext()); 23 setCurrentSession(currentSession); 24 return currentSession; 25 }
