jsp验证码可复用

package com.mocha.yanzhengma; import java.io.IOException; import java.io.PrintWriter; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class CheckServlet extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { HttpSession session = request.getSession(); String requestCaptcha = request.getParameter("captcha"); String sessionCaptcha = (String) session.getAttribute("captcha"); if (sessionCaptcha != null && sessionCaptcha.equals(requestCaptcha)) { session.removeAttribute("captcha"); request.getRequestDispatcher("/success.jsp").forward(request, response); } else { request.setAttribute("message", "验证码输入错误"); request.getRequestDispatcher("/index.jsp").forward(request, response); } } }