SpringSession源码分析

默认对常规Session的理解和使用，如何使用Set-Cookie。

Maven库

常见的spring-session-data-redis依赖spring-session-core

    <dependency><groupId>org.springframework.session</groupId><artifactId>spring-session-core</artifactId></dependency>

带着问题看源码

1、Controller代码块内request.getSession()是在哪创建的呢？
2、响应头Set-Cookie是在什么地方赋值的呢？

SessionRepositoryFilter 拦截器

org.springframework.session.web.http.SessionRepositoryFilter

    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {request.setAttribute(SESSION_REPOSITORY_ATTR, this.sessionRepository);// 请求包装，进入包装类可以看到request.getSession()源码SessionRepositoryFilter<S>.SessionRepositoryRequestWrapper wrappedRequest = new SessionRepositoryRequestWrapper(request, response);SessionRepositoryFilter<S>.SessionRepositoryResponseWrapper wrappedResponse = new SessionRepositoryResponseWrapper(wrappedRequest, response);try {filterChain.doFilter(wrappedRequest, wrappedResponse);} finally {// 响应头`Set-Cookie`赋值入口（这里不理解为啥使用请求提交，而不是用响应提交`wrappedResponse.commitSession()`）// 方法跳转到DefaultCookieSerializer类就看见具体Set-Cookie了wrappedRequest.commitSession();}}

SessionRepositoryRequestWrapper 包装类

org.springframework.session.web.http.SessionRepositoryFilter.SessionRepositoryRequestWrapper
Spring中存在很多继承HttpServletRequestWrapper的包装类

        public SessionRepositoryFilter<S>..SessionRepositoryRequestWrapper.HttpSessionWrapper getSession(boolean create) {SessionRepositoryFilter<S>..SessionRepositoryRequestWrapper.HttpSessionWrapper currentSession = this.getCurrentSession();if (currentSession != null) {return currentSession;} else {S requestedSession = this.getRequestedSession();if (requestedSession != null) {if (this.getAttribute(SessionRepositoryFilter.INVALID_SESSION_ID_ATTR) == null) {requestedSession.setLastAccessedTime(Instant.now());this.requestedSessionIdValid = true;currentSession = new HttpSessionWrapper(requestedSession, this.getServletContext());currentSession.markNotNew();this.setCurrentSession(currentSession);return currentSession;}} else {if (SessionRepositoryFilter.SESSION_LOGGER.isDebugEnabled()) {SessionRepositoryFilter.SESSION_LOGGER.debug("No session found by id: Caching result for getSession(false) for this HttpServletRequest.");}this.setAttribute(SessionRepositoryFilter.INVALID_SESSION_ID_ATTR, "true");}if (!create) {return null;} else if (SessionRepositoryFilter.this.httpSessionIdResolver instanceof CookieHttpSessionIdResolver && this.response.isCommitted()) {throw new IllegalStateException("Cannot create a session after the response has been committed");} else {if (SessionRepositoryFilter.SESSION_LOGGER.isDebugEnabled()) {SessionRepositoryFilter.SESSION_LOGGER.debug("A new session was created. To help you troubleshoot where the session was created we provided a StackTrace (this is not an error). You can prevent this from appearing by disabling DEBUG logging for " + SessionRepositoryFilter.SESSION_LOGGER_NAME, new RuntimeException("For debugging purposes only (not an error)"));}S session = SessionRepositoryFilter.this.sessionRepository.createSession();session.setLastAccessedTime(Instant.now());currentSession = new HttpSessionWrapper(session, this.getServletContext());this.setCurrentSession(currentSession);return currentSession;}}}// 看这里@Overridepublic SessionRepositoryFilter<S>..SessionRepositoryRequestWrapper.HttpSessionWrapper getSession() {return this.getSession(true);}

DefaultCookieSerializer

org.springframework.session.web.http.DefaultCookieSerializer
特别注意地方是：Set-Cookie内值是通过Base64加密的。

    public void writeCookieValue(CookieSerializer.CookieValue cookieValue) {HttpServletRequest request = cookieValue.getRequest();HttpServletResponse response = cookieValue.getResponse();StringBuilder sb = new StringBuilder();sb.append(this.cookieName).append('=');String value = this.getValue(cookieValue);if (value != null && value.length() > 0) {this.validateValue(value);sb.append(value);}int maxAge = this.getMaxAge(cookieValue);if (maxAge > -1) {sb.append("; Max-Age=").append(cookieValue.getCookieMaxAge());ZonedDateTime expires = maxAge != 0 ? ZonedDateTime.now(this.clock).plusSeconds((long)maxAge) : Instant.EPOCH.atZone(ZoneOffset.UTC);sb.append("; Expires=").append(expires.format(DateTimeFormatter.RFC_1123_DATE_TIME));}String domain = this.getDomainName(request);if (domain != null && domain.length() > 0) {this.validateDomain(domain);sb.append("; Domain=").append(domain);}String path = this.getCookiePath(request);if (path != null && path.length() > 0) {this.validatePath(path);sb.append("; Path=").append(path);}if (this.isSecureCookie(request)) {sb.append("; Secure");}if (this.useHttpOnlyCookie) {sb.append("; HttpOnly");}if (this.sameSite != null) {sb.append("; SameSite=").append(this.sameSite);}response.addHeader("Set-Cookie", sb.toString());}

🔚

源码分析主要是找到入口，关键入口代码已经贴上了，剩下的自己打断点看吧。