java web实现自动登录功能

本文实例为大家分享了java web实现自动登录功能的具体代码，供大家参考，具体内容如下

主要思路就是：当用户访问网站的首页时，浏览器端会先检擦浏览器中存在的cookie中是否又登录的用户的用户名，如果有，则直接跳转至用户登录好的界面，如果没有，则重定向至登录界面，在服务器端创建该用户登录的cookie,响应时，将创建的cookie返回至浏览器端保存。

一、用户访问首页时检查cookie是否存在。

package ahpudong.com;

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

@WebServlet("/index.do")

public class index extends HttpServlet {
 public index() {
  super();
 }
 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  Cookie[] cookies=request.getCookies();
  if(cookies!=null){
   for(Cookie cookie:cookies){
    String name=cookie.getName();
    String value=cookie.getValue();
    if("name".equals(name) && "chendong".equals(value)){
     request.setAttribute(name, value);
     request.getRequestDispatcher("user.view").forward(request, response);
     return;
    }
   }
  }
   response.sendRedirect("login.jsp");
 }
}

二、确定用户登录的cookie不存在，在手动登录的过程中创建用户登录cookie。

package ahpudong.com;

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

@WebServlet("/login.do")

public class login extends HttpServlet {
 public login() {
  super();
 }
 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  response.setContentType("text/html");
  request.setCharacterEncoding("utf-8");
  response.setCharacterEncoding("utf-8");
  PrintWriter out = response.getWriter();
  String name=request.getParameter("name");
  String pwd=request.getParameter("pwd");
  String login=request.getParameter("auto");
  if("chendong".equals(name) && "123456".equals(pwd)){
   if("on".equals(login)){
    Cookie cookie=new Cookie("name","chendong");
    cookie.setMaxAge(7*24*60*60);//有效期为一个星期
    response.addCookie(cookie);
    request.setAttribute("name",name);
    request.getRequestDispatcher("user.view").forward(request, response);
   }
  }else{
   response.sendRedirect("login.jsp");
  }
 }
}

三、登录成功时的视图层

package ahpudong.com;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/user.view")
public class User extends HttpServlet {
 public User() {
  super();
 }
 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  processRequest(request,response);

 }
 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  processRequest(request,response);
 }
 public void processRequest(HttpServletRequest request,HttpServletResponse response)
   throws ServletException, IOException{
  response.setCharacterEncoding("utf-8");
  PrintWriter out=response.getWriter();
  String name=(String) request.getAttribute("name");
  out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
  out.println("<HTML>");
  out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
  out.println(" <BODY>");
  out.println("<h1>"+"welcome "+name+" login"+"</h1>");
  out.println(" </BODY>");
  out.println("</HTML>");
  out.flush();
  out.close();
 }
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。