用户登录Demo(JSP+Servlet)

package cn.servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class LoginServlet extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //获取表单数据，处理中文问题 request.setCharacterEncoding("utf-8"); //获取登录页面传过来的用户名和密码 String username = request.getParameter("username"); String password = request.getParameter("password"); //验证用户名和密码是否正确 if(username.equalsIgnoreCase("abel")&&password.equalsIgnoreCase("abel")){ //用户登录成功之后，服务器会让浏览器保存Cookie，以便下次登录时候显示用户名 Cookie cookie = new Cookie("username", username);//创建Cookie对象 cookie.setMaxAge(60*60*24);//设置Cookie最大存活时间为一天 response.addCookie(cookie);//设置Cookie //如果登录成功，就保存登录信息到session域中，之后重定向到main.jsp request.getSession().setAttribute("username", username); response.sendRedirect("/login/login/main.jsp"); }else { //如果登录失败，保存登录信息到request域中，之后转发会login.jsp request.setAttribute("errmsg", "用户名或者密码错误，请重新输入！"); request.getRequestDispatcher("/login/login.jsp").forward(request, response); } } }