SpringSecurity用户绑定到线程

public class SecurityContextPersistenceFilter extends GenericFilterBean {

	static final String FILTER_APPLIED = "__spring_security_scpf_applied";

	private SecurityContextRepository repo;

	private boolean forceEagerSessionCreation = false;

	public SecurityContextPersistenceFilter() {
		this(new HttpSessionSecurityContextRepository());
	}

	public SecurityContextPersistenceFilter(SecurityContextRepository repo) {
		this.repo = repo;
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		doFilter((HttpServletRequest) request, (HttpServletResponse) response, chain);
	}

	private void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		// ensure that filter is only applied once per request
		if (request.getAttribute(FILTER_APPLIED) != null) {
			chain.doFilter(request, response);
			return;
		}
		request.setAttribute(FILTER_APPLIED, Boolean.TRUE);
		if (this.forceEagerSessionCreation) {
			HttpSession session = request.getSession();
			if (this.logger.isDebugEnabled() && session.isNew()) {
				this.logger.debug(LogMessage.format("Created session %s eagerly", session.getId()));
			}
		}
		HttpRequestResponseHolder holder = new HttpRequestResponseHolder(request, response);
        // 获取用户信息
		SecurityContext contextBeforeChainExecution = this.repo.loadContext(holder);
		try {
            //用户信息绑定到线程
			SecurityContextHolder.setContext(contextBeforeChainExecution);
			if (contextBeforeChainExecution.getAuthentication() == null) {
				logger.debug("Set SecurityContextHolder to empty SecurityContext");
			}
			else {
				if (this.logger.isDebugEnabled()) {
					this.logger
							.debug(LogMessage.format("Set SecurityContextHolder to %s", contextBeforeChainExecution));
				}
			}
			chain.doFilter(holder.getRequest(), holder.getResponse());
		}
		finally {
			SecurityContext contextAfterChainExecution = SecurityContextHolder.getContext();
			// Crucial removal of SecurityContextHolder contents before anything else.
			SecurityContextHolder.clearContext();
			this.repo.saveContext(contextAfterChainExecution, holder.getRequest(), holder.getResponse());
			request.removeAttribute(FILTER_APPLIED);
			this.logger.debug("Cleared SecurityContextHolder to complete request");
		}
	}

	public void setForceEagerSessionCreation(boolean forceEagerSessionCreation) {
		this.forceEagerSessionCreation = forceEagerSessionCreation;
	}

}