解决过滤器中设置cookie无效的问题

解决过滤器中设置cookie无效的问题

代码现场

filterChain.doFilter(sessionSyncRequestWrapper, response);
Cookie emailCook = WebServletUtil.getSelectedCookie(request.getCookies(), Constant2.COOKIE_KEY_JSESSIONID, null);
        if (emailCook != null) {
            System.out.println("保存 :" + request.getSession().getId());
            emailCook.setMaxAge(12 * 60 * 60);
            emailCook.setPath("/");//设置cookie时,设置path为根路径
            response.addCookie(emailCook);
        } else {
            WebServletUtil.setSessionIdCookie( request.getSession().getId(),response,48);
        }

目的:设置cookie(JSESSIONID)的超时时间,让cookie(JSESSIONID)持久化,
浏览器关闭以后,cookie(JSESSIONID)依然有效
可是实际没有持久化,很奇怪
明明设置了很长的过时时间,为何没有生效呢?
测试了百遍,终于发现了问题

不生效的缘由

是由于 response 已经 commit了, 咱们看看response.isCommitted() 方法的解释说明:

/**
     * Returns a boolean indicating if the response has been
     * committed.  A committed response has already had its status 
     * code and headers written.
     *
     * @return		a boolean indicating if the response has been
     *  		committed
     *
     * @see 		#setBufferSize
     * @see 		#getBufferSize
     * @see 		#flushBuffer
     * @see 		#reset
     *
     */

    public boolean isCommitted();

说白了,response若是已经commit了,再设置cookie(即response的header)不会生效.
由于我是在 filterChain.doFilter 以后设置cookie,因此一直没有生效

解决方法:

在 filterChain.doFilter 以前设置cookie:

Cookie emailCook = WebServletUtil.getSelectedCookie(request.getCookies(), Constant2.COOKIE_KEY_JSESSIONID, null);
        if (emailCook != null) {
            System.out.println("保存 :" + request.getSession().getId());
            emailCook.setMaxAge(12 * 60 * 60);
            emailCook.setPath("/");//设置cookie时,设置path为根路径
            response.addCookie(emailCook);
        } else {
            WebServletUtil.setSessionIdCookie( request.getSession().getId(),response,48);
        }
        filterChain.doFilter(sessionSyncRequestWrapper, response);

注意:

1. 如何查看response 是否已经commit? 使用 response.isCommitted() ;
2. chain.doFilter(request, response); 以后response的状态是已经commit

参考:
自定义实现session持久化