Java Web对验证码进行验证

https://www.cnblogs.com/wypzpz/p/12459370.html中有生成验证码的具体代码

前端

$(function () {
    $("#verifycode").mouseout(function () {
              $.get("${pageContext.request.contextPath}/checkCodeServlet",
                      {"checkCode":$("#verifycode").val()},
                      function (data) {
                          if (data=="false"){
                              checkCode_flag = false;
                              $("#errorCode").attr("hidden",false);
                          }
                          if (data=="true"){
                              checkCode_flag =true;
                              $("#errorCode").attr("hidden",true);
                          }
                      }
              )
          })
后端

package servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession();
        String checkCode = (String) session.getAttribute("CHECKCODE");
        String inputCheckCode = request.getParameter("checkCode");
        if (checkCode.equalsIgnoreCase(inputCheckCode)){
            response.getWriter().write("true");
        }else {
            response.getWriter().write("false");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}