1、使用Cookie实现的登录的不足：
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Connection con=null;
login log= null;
String account=request.getParameter("username");//获得表单数据只在此Servlet起作用
String password=request.getParameter("password");
Cookie cookie=new Cookie(account,password);
cookie.setPath("/Servlet_login_war_exploded/cookie");
cookie.setMaxAge(3*24*3600);
response.addCookie(cookie);
try {
con=C3p0Utils.getConnection();
QueryRunner qr = new QueryRunner();
String sql = "Select * from login where account=? and password=?";
Object[] select = {account,password};
log = qr.query(con, sql, new BeanHandler<login>((login.class)), select);
if(log!=null){
response.getWriter().write("nihao"+account);
}
else{
response.getWriter().write("wrong");
}
}
catch (SQLException e) {
throw new RuntimeException(e);
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html; charset=utf-8");//设置浏览器编码格式
response.getWriter().write("<html>");
response.getWriter().write("<head>");
response.getWriter().write("<title>");
response.getWriter().write("Login");
response.getWriter().write("</title>");
response.getWriter().write("</head>");
response.getWriter().write("<body bgcolor=\"aqua\">");
response.getWriter().write("<center>");
response.getWriter().write("<h3>");
response.getWriter().write("欢迎你"+request.getParameter("account"));
response.getWriter().write("</h3>");
response.getWriter().write("</center>");
response.getWriter().write("</body>");
}
使用Cookie虽然实现了三天免登陆的基础功能，但是，如果在用Cookie登录成功后需要重定向到另外一个Cookie时，request获取的值在重定向的Servlet中已经不再起作用了。访问的结果只能是空值。
2、使用Session的请求共享功能，实现在不同的Servlet跳转过程中依旧能够通过request获得用户信息。
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html; charset=utf-8");//设置浏览器编码格式
Cookie[] cookies=request.getCookies();
Connection con=null;
login log= null;
int successNum=0;
try {
con= C3p0Utils.getConnection();
QueryRunner qr = new QueryRunner();
String sql = "Select * from login";
List<login> list = qr.query(con, sql, new BeanListHandler<login>((login.class)));
if(cookies!=null) {//验证数据库中是否有与Cookie对应的用户
for (int i = 0; i < list.size(); i++) {
log= list.get(i);
for (Cookie cookie : cookies) {
if((log.getAccount().equals(cookie.getName()))&&(log.getPassword().equals(cookie.getValue()))){
HttpSession httpSession=request.getSession();
httpSession.setAttribute("login",log);
successNum++;
}
}
}
if(successNum>=1){
response.sendRedirect("/Servlet_login_war_exploded/main");//重定向
}
else{
request.getRequestDispatcher("page").forward(request,response);
}
}
else{
request.getRequestDispatcher("page").forward(request,response);//请求转发
}
}
catch (SQLException e) {
throw new RuntimeException(e);
}
}
在通过Cookie登录成功后，创建了Session，对Session进行了赋值，而在重定向到MainServlet后，可以冲Session中获取值。虽然在不同的Servlet中，是不同的请求，但是依旧能够通过Session获取值。
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
login log= (login) request.getSession().getAttribute("login");
response.setContentType("text/html; charset=utf-8");//设置浏览器编码格式
response.getWriter().write("<html>");
response.getWriter().write("<head>");
response.getWriter().write("<title>");
response.getWriter().write("Login");
response.getWriter().write("</title>");
response.getWriter().write("</head>");
response.getWriter().write("<body bgcolor=\"aqua\">");
response.getWriter().write("<center>");
response.getWriter().write("<h3>");
response.getWriter().write("欢迎你"+log.getAccount());
response.getWriter().write("</h3>");
response.getWriter().write("</center>");
response.getWriter().write("</body>");
}
原文地址：https://www.cnblogs.com/zhai1997/p/11559989.html
时间： 2024-08-03 23:43:27