正文
Session 起航 登录会话和注销请求 重定向和转发
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【LoginServlet】
@WebServlet(name="loginServlet",urlPatterns = "/login")
public class LoginServlet extends HttpServlet{
private static final Map<String,String> userDatabase = new Hashtable<>(); static {
userDatabase.put("user1","123456");
userDatabase.put("user2","123456");
userDatabase.put("user3","123456");
userDatabase.put("user4","123456");
} @Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
HttpSession session = req.getSession();
if (req.getParameter("logout")!=null){
session.invalidate();
resp.sendRedirect("login");
return;
// 已经登录上的
}else if (session.getAttribute("username")!=null){
resp.sendRedirect("tickets");
return;
}
req.setAttribute("loginFailed",false);
req.getRequestDispatcher("/WEB-INF/jsp/view/login.jsp").forward(req,resp);
} @Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
HttpSession session = req.getSession();
//注销
if (req.getParameter("logout")!=null){
session.invalidate();
resp.sendRedirect("login");
return;
// 登录会话
}else if (session.getAttribute("username")!=null){
resp.sendRedirect("tickets");
return;
}
String username = req.getParameter("username");
String userpassword = req.getParameter("userpassword");
if (username == null || userpassword == null ||
!LoginServlet.userDatabase.containsKey(username)||
!userpassword.equals(LoginServlet.userDatabase.get(username))){
req.setAttribute("loginFailed",true);
req.getRequestDispatcher("/WEB-INF/jsp/view/login.jsp")
.forward(req,resp);
}else {
session.setAttribute("username",username);
req.changeSessionId();//登录更新会话id
resp.sendRedirect("tickets");
}
}
}
【重定向和转发】
转发是服务器行为。
重定向是客户端行为。
【login.jsp】
<h2>登录</h2>
<%
if ((boolean)request.getAttribute("loginFailed")){
out.println("您输入的密码或用户名不对");
}
%>
<form action="<c:url value="/login"/>" method="post">
用户名<br />
<input type="text" name="username" /><br />
密码<br />
<input type="password" name="userpassword" value="banana" /><br />
<input type="submit" value="登录"/>
</form>
