用户权限jsp源代码

CREATE TABLE users (
    id INT PRIMARY KEY,
    username VARCHAR(50),
    password VARCHAR(50),
    role_id INT
);

CREATE TABLE roles (
    id INT PRIMARY KEY,
    role_name VARCHAR(50)
);

<%@ page import="java.sql.*" %>
<%
    String username = (String) session.getAttribute("username");
    if (username == null) {
        response.sendRedirect("login.jsp");
        return;
    }

    Connection conn = null;
    PreparedStatement pstmt = null;
    ResultSet rs = null;
    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "root", "password");
        pstmt = conn.prepareStatement("SELECT role_name FROM roles WHERE id = (SELECT role_id FROM users WHERE username = ?)");
        pstmt.setString(1, username);
        rs = pstmt.executeQuery();

        String role = null;
        if (rs.next()) {
            role = rs.getString("role_name");
        }

        if ("admin".equals(role)) {
            // 显示管理员页面
            out.println("<h1>Welcome, Admin!</h1>");
        } else if ("user".equals(role)) {
            // 显示普通用户页面
            out.println("<h1>Welcome, User!</h1>");
        } else {
            response.sendRedirect("unauthorized.jsp");
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try { if (rs != null) rs.close(); } catch (Exception e) {}
        try { if (pstmt != null) pstmt.close(); } catch (Exception e) {}
        try { if (conn != null) conn.close(); } catch (Exception e) {}
    }
%>