filter全局控制重复提交

采用filter来全局控制重复提交

 

filter拦截需要控制重复提交的页面

filter中获取该页面的所有参数值

将参数值字符串进行计算hash值存入session，或者数据库中，保存最近一次操作的hash值

 

获取session中最近的hash值和本次获取参数值计算所得的hash值对比，，相同则为重复提交，不同则放行

 

@Override
	public void doFilter(ServletRequest req, ServletResponse res,
			FilterChain chain) throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest)req;
		HttpServletResponse response = (HttpServletResponse)res;
		Integer session_token = (Integer)request.getSession(true).getAttribute("token");
		Enumeration<String>  en= request.getParameterNames();
		System.out.println("==session token:"+session_token);
		String strcode = "";
		while(en.hasMoreElements()){
			strcode +=request.getParameter(en.nextElement());
		}
		//将表单页面所有值相加字符串进行hash计算
		int hash_token = strcode.hashCode();
		//两次hash值相同，则表示为重复提交
		if(session_token!=null&&session_token==hash_token){
			response.sendRedirect(request.getContextPath()+"/chongfu.do");
		}else {
			//session中保持最近一次表单hash值
			request.getSession(true).setAttribute("token", hash_token);
			chain.doFilter(req, res);
		}
	}