Question

我在JSP中创建了一个登录脚本。它工作正常，但我使用的问题 <%=session.getAttribute("first_name")%>它显示Null。你能告诉我这里有什么问题吗？

Main.jsp：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

    <%
    if ((session.getAttribute("user_email") == null) || (session.getAttribute("user_email") == "")) {
        response.sendRedirect("login.jsp");
%>
<%} else
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Welcome to the job seeker forum.</title>
<link rel="stylesheet" type="text/css" href="CSS_styles/forum_style.css"/>
<link rel='stylesheet' id='open-sans-css'  href='//fonts.googleapis.com/css?family=Open+Sans%3A300italic%2C400italic%2C600italic%2C300%2C400%2C600&#038;subset=latin%2Clatin-ext&#038;ver=4.1-alpha-20141011' type='text/css' media='all' />
<link href='http://fonts.googleapis.com/css?family=Londrina+Solid|Exo:800|Open+Sans:300italic,400,300,600|Roboto:400,100,300,500,700' rel='stylesheet' type='text/css' />
</head>
<body>
    <div id="forum">
        <h1><b>Welcome <%=session.getAttribute("first_name")%></b>,<br>to Job seeker forum, there are many openings that you can get through here. <a href='logout.jsp'>logout</a></h1>
        <form id="forum_form" method="post">
        </form>
    </div><br><br><br>
    <div id="forum2">
        <h1 style="text-align: center;">Want to post on going walking,<br>Post your job description here.</h1>
        <form id="forum2_form" method="post">
            <p>
            <label>Job title:</label>
            <input type="text" class="" placeholder="e.g XXX Referral program for freshers."/>
            </p>
            <p>
            <label>Your Question:</label>
            <textarea class="question_ask_style" rows="3" cols="40" placeholder="Type description here.."></textarea>
            </p>

            <div id="submit_btn">
            <input type="submit" value="Submit Question" />
            </div>
        </form>
    </div>
</body>
</html>

以下是login_process.jsp

<%@ page import="java.sql.*" %>

<%
    String user_email=request.getParameter("user_email");
    String user_password=request.getParameter("user_password");

    Class.forName("com.mysql.jdbc.Driver");
    Connection con=DriverManager.getConnection("jdbc:mysql://localhost:8888/login", "root", "1234");
    Statement st=con.createStatement();
    ResultSet rs;
    rs=st.executeQuery("select * from members where email='"+user_email+"' and password='"+user_password+"'");

    if(rs.next()){
        session.setAttribute("user_email", user_email);
        response.sendRedirect("main.jsp");
    }else{
        out.println("Invalid Password... Try again.. <a href='login.jsp'>login</a>");
    }
%>

这是我创建的database table：

create table `members`(
`id` int(10) unsigned NOT NULL auto_increment,
`email` varchar(100) NOT NULL,
`password` varchar(100) NOT NULL,
`first_name` varchar(50) NOT NULL,
`last_name` varchar(50) NOT NULL,
PRIMARY KEY(`id`)
)ENGINE= InnoDB default charset=latin1;

这就是我收到错误......

SCREENSHOT ： http://i.stack.imgur.com/AuF5M.png

Answer 1

<%=session.getAttribute("first_name")%>显示null，因为您尚未在会话中设置first_name。

您只设置了user_email。

if(rs.next()){
        String user_email=rs.getString("first_name");
        session.setAttribute("user_email", user_email);
        response.sendRedirect("main.jsp");

你可以像上面那样设置

P.S

几十年来不鼓励使用Scriptlet，因此建议使用EL代替它们。你可以简单地使用${sessionScope.user_email}在jsp页面中打印出来

Answer 2

在login_process.jsp中使用<%=session.setAttribute("first_name",first_name)%>然后访问它。例如：

    rs=st.executeQuery("select * from members where email='"+user_email+"' and password='"+user_password+"'");

        if(rs.next()){
            session.setAttribute("first_name", rs.getString("first_name"));//set first_name in session
            session.setAttribute("user_email", user_email);

            response.sendRedirect("main.jsp");


   }

Answer 3

试试这个

if(rs.next()){
    session.setAttribute("user_email", user_email);

    session.setAttribute("first_name", rs.getString(4));//Add this line to your code


    response.sendRedirect("main.jsp");
}

这里4是first_name的列号

Answer 4

在login_process.jsp中设置

session.setAttribute("user_email", user_email);

到

    session.setAttribute("first_name", rs.getString("first_name"));

因为您已设置属性名称user_email并从会话中获取first_name。

用户名没有显示在数据库的网页中？

4 个答案: