Servlet之用户登录过程实现

用户登录过程

package com.kevin.login;

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

public class UserServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

public void init() throws ServletException{
//初始化一个变量count 值为0
int count = 0 ;
//将这个值存入到ServletContext中
this.getServletContext().setAttribute("count", count);
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

try {

//1 接收表单提交的参数
String username= request.getParameter("username");
String password = request.getParameter("password");
//2 封装到实体对象中
User user = new User();
user.setUsername(username);
user.setPassword(password);

//3 调用业务层处理数据
UserService userService = new UserService();
User existUser = userService.login(user);
//4 根据处理结果显示信息---页面跳转
if (existUser == null) {
//登录失败
response.setCharacterEncoding("UTF-8");
response.setHeader("Content-type", "text/html;charset=UTF-8");
response.getWriter().println("登录失败！");
}else {
//登陆成功

//记录次数
int count = (int) this.getServletContext().getAttribute("count");
count++;
this.getServletContext().setAttribute("count", count);
response.setCharacterEncoding("UTF-8");
response.getWriter().println("<h1>登陆成功：您好，亲爱的"+existUser.getNickname()+"<h1>");
//response.getWriter().println("<h3>页面将在5秒钟后跳转</h3>");
response.setHeader("Content-type", "text/html;charset=UTF-8");
//response.setHeader("Refresh", "5;url=/CountServlet");

response.getWriter().println("<h1>您是第"+count+"位登录成功的用户！</h1>");

}

}catch (Exception e) {
e.printStackTrace();
}

}

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

}