登录的servlet
package login;
import java.io.IOException;
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 LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//编码处理
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF=8");
//获得session中的checkcode
HttpSession session = request.getSession();
String checkCode = (String) session.getAttribute("checkcode_session");
//获得request中的checkcode
String requestCheckCode = request.getParameter("checkCode");
//对比两个checkcode是否相同
if(!checkCode.equals(requestCheckCode)) {
//不相同
request.setAttribute("retMsg", "请重新输入验证码");
request.getRequestDispatcher("/login.jsp").forward(request, response);
//需要return不然会继续执行下面的程序
return;
}
//验证登录....
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
登录页面
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>login</title>
</head>
<body>
<h3 style="color:red;"><%=request.getAttribute("retMsg")==null?"":request.getAttribute("retMsg")%></h3>
<form action="/Cookie_Session/login" method="post">
用户名：
<input type="text" name="username" ><br>
密码：
<input type="password" name="password" ><br>
验证码：
<input type="text" name="checkCode"><img src="/Cookie_Session/checkCode"><br>
<input type="submit" value="登录">
</form>
</body>
</html>
运行结果
