Question

你好我正在写一个登录注册页面。页面用数据库检查用户名密码，如果正确，用户可以访问新的jsp页面。它打印出“welcome + username”。我怎样才能做到这一点？我在互联网上搜索，我在代码下面。但它不起作用。当我运行它时返回“welcome null”。我希望这成功.jsp

的success.jsp

 <%@page contentType="text/html" pageEncoding="UTF-8"%>
 <!DOCTYPE html>
 <html>
 <body background="http://www.teamarking.com/barcode/bar_background.jpg"> 


 <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 <title>JSP Page</title>

  </head>
   <ul>
    <li><%
    out.println("<a href='music.jsp'>Music</a>");
    %>
    </li>
    <li><%
    out.println("<a href='sport.jsp'>Sport</a>");
    %></li>
     <li> <%
    out.println("<a href='stage.jsp'>Stage</a>");
    %></li>
     <li> <%
    out.println("<a href='family.jsp'>Family</a>");
    %></li>
    <li> <%
    out.println("<a href='education.jsp'>Education</a>");
    %></li>
  </ul>
  <div class="landscape">
  <%
  String username = (String) request.getSession().getAttribute("username");
    session.setAttribute("username", username);

  out.println("welcome" + username);

  out.println(
        "<a href='logout.jsp'>Log out</a>");

  out.println(
        "<a href='myreservations.jsp'>My Reservations</a>");
  %>
  </div>
  </body>
  </html>

的login.jsp

  <%@ page import ="java.sql.*" %>
  <%
  String username = request.getParameter("username");
  String password = request.getParameter("password");
  Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance();
  Connection con = DriverManager.getConnection("jdbc:derby://localhost:1527/users", "users", "123");
  Statement st = con.createStatement();
  ResultSet rs;
  rs = st.executeQuery("select * from users where username='" + username + "' and password='" + password + "'");
  if (rs.next()) {
    session.setAttribute("username", username);
    response.sendRedirect("success.jsp");
  } else {
    out.println("Invalid password <a href='index.jsp'>try again</a>");
  }
  st.close();
  %>

Answer 1

在您阅读属性之前＆＃34;用户名＆＃34;你必须设置属性。因此，您必须使用函数setAttribute（）。

print(1.__add__(2))

检查或验证用户名和密码后，您必须使用此代码。您能否显示其余代码（验证发生的部分）？

从jsp的会话中获取属性

1 个答案: