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Spring Security源码分析八：Spring Security 退出

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

清除 Cookie
清除当前用户的 remember-me 记录
使当前 session 失效
清空当前的 SecurityContext
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

主页中添加退出链接

<a href="/signOut">退出</a>

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

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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);
	}

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

handler

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CookieClearingLogoutHandler 清空 Cookie
PersistentTokenBasedRememberMeServices 清空 remember-me
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);
		}
	}

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());
		}
	}

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();
	}

使当前session失效
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);
	}