Spring Security源码分析八：Spring Secu

Spring Security是一个能够为基于Spring的企业应用系统提供声明式的安全访问控制解决方案的安全框架。它提供了一组可以在Spring应用上下文中配置的Bean，充分利用了Spring IoC，DI（控制反转Inversion of Control ,DI:Dependency Injection 依赖注入）和AOP（面向切面编程）功能，为应用系统提供声明式的安全访问控制功能，减少了为企业系统安全控制编写大量重复代码的工作。

退出原理

1. 清除Cookie
2. 清除当前用户的remember-me记录
3. 使当前session失效
4. 清空当前的SecurityContext
5. 重定向到登录界面

Spring Security的退出请求（默认为/logout）由LogoutFilter过滤器拦截处理。

退出的实现

1. 主页中添加退出链接

<a href="/signOut">退出</a>

2. 配置MerryyouSecurityConfig

......
                .and()
                .logout()
                .logoutUrl("/signOut")//自定义退出的地址
                .logoutSuccessUrl("/register")//退出之后跳转到注册页面
                .deleteCookies("JSESSIONID")//删除当前的JSESSIONID
                .and()
......

效果如下

https://raw.githubusercontent.com/longfeizheng/longfeizheng.github.io/master/images/security/Spring-Security-logout.gif

源码分析

LogoutFilter#doFilter

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;
        //#1.匹配到/logout请求
        if (requiresLogout(request, response)) {
            Authentication auth = SecurityContextHolder.getContext().getAuthentication();

            if (logger.isDebugEnabled()) {
                logger.debug("Logging out user '" + auth
                        + "' and transferring to logout destination");
            }
            //#2.处理1-4步
            this.handler.logout(request, response, auth);
            //#3.重定向到注册界面
            logoutSuccessHandler.onLogoutSuccess(request, response, auth);

            return;
        }

        chain.doFilter(request, response);
    }

1. 匹配当前拦截的请求
2. 处理 清空Cookie、remember-me、session和SecurityContext
3. 重定向到登录界面

handler

https://raw.githubusercontent.com/longfeizheng/longfeizheng.github.io/master/images/security/Spring-Security-LogoutFilter.png

1. CookieClearingLogoutHandler清空Cookie
2. PersistentTokenBasedRememberMeServices清空remember-me
3. SecurityContextLogoutHandler 使当前session无效,清空当前的SecurityContext

CookieClearingLogoutHandler#logout

public void logout(HttpServletRequest request, HttpServletResponse response,
            Authentication authentication) {
        for (String cookieName : cookiesToClear) {
            //# 1.Cookie置为null
            Cookie cookie = new Cookie(cookieName, null);
            String cookiePath = request.getContextPath();
            if (!StringUtils.hasLength(cookiePath)) {
                cookiePath = "/";
            }
            cookie.setPath(cookiePath);
            cookie.setMaxAge(0);
            response.addCookie(cookie);
        }
    }

1. Cookie置为null

PersistentTokenBasedRememberMeServices#logout

public void logout(HttpServletRequest request, HttpServletResponse response,
            Authentication authentication) {
        super.logout(request, response, authentication);

        if (authentication != null) {
            //#1.清空persistent_logins表中记录
            tokenRepository.removeUserTokens(authentication.getName());
        }
    }

1. 清空persistent_logins表中记录

SecurityContextLogoutHandler#logout

public void logout(HttpServletRequest request, HttpServletResponse response,
            Authentication authentication) {
        Assert.notNull(request, "HttpServletRequest required");
        if (invalidateHttpSession) {
            HttpSession session = request.getSession(false);
            if (session != null) {
                logger.debug("Invalidating session: " + session.getId());
                //#1.使当前session失效
                session.invalidate();
            }
        }

        if (clearAuthentication) {
            SecurityContext context = SecurityContextHolder.getContext();
            //#2.清空当前的`SecurityContext`
            context.setAuthentication(null);
        }

        SecurityContextHolder.clearContext();
    }

1. 使当前session失效
2. 清空当前的SecurityContext

AbstractAuthenticationTargetUrlRequestHandler#handle

    protected void handle(HttpServletRequest request, HttpServletResponse response,
            Authentication authentication) throws IOException, ServletException {
        //#1.获取配置的跳转地址
        String targetUrl = determineTargetUrl(request, response);

        if (response.isCommitted()) {
            logger.debug("Response has already been committed. Unable to redirect to "
                    + targetUrl);
            return;
        }
        //#2.跳转请求
        redirectStrategy.sendRedirect(request, response, targetUrl);
    }

1. 获取配置的跳转地址
2. 跳转请求

代码下载

从我的 github 中下载，https://github.com/longfeizheng/logback