Question

我是使用Java开发Web应用程序的新手。我开发了一个小型应用程序，它是一个登录＆amp;注册页面都工作正常。现在，我决定制作一个管理页面（使用jsp）。在我的java代码中，我控制jsp页面的重定向（如果用户！=“admin”，然后是home.jsp else user ==“admin”，然后是admin.jsp）。在我的管理页面中，我想要的是我希望管理员能够查看已注册的所有用户，并可以编辑他们的详细信息或删除它们。有人可以建议我如何实现这一目标。

登录Servlet.java（我在admin和普通用户之间决定的代码）

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String email = request.getParameter("email");
        String password = request.getParameter("password");
        String errorMsg = null;
        String name;
        if(email == null || email.equals("")){
            errorMsg ="User Email can't be null or empty";
        }
        if(password == null || password.equals("")){
            errorMsg = "Password can't be null or empty";
        }

        if(errorMsg != null){
            RequestDispatcher rd = getServletContext().getRequestDispatcher("/login.html");
            PrintWriter out= response.getWriter();
            out.println("<font color=red>"+errorMsg+"</font>");
            rd.include(request, response);
        }else{

        Connection con = (Connection) getServletContext().getAttribute("DBConnection");
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            ps = con.prepareStatement("select id, name, email,country from Users where email=? and password=?");
            ps.setString(1, email);
            ps.setString(2, password);
            rs = ps.executeQuery();

            if(rs != null && rs.next()){

                User user = new User(rs.getString("name"), rs.getString("email"), rs.getString("country"), rs.getInt("id"));
               name=rs.getString("name");
               System.out.println("Name:"+ name);
                //if(rs.getString("name")!="admin")
               if(!name.equalsIgnoreCase("admin"))
                {
                logger.info("User found with details="+user);
                HttpSession session = request.getSession();
                session.setAttribute("User", user);
                response.sendRedirect("home.jsp");
                }
                // String rs1=rs.getString();
                else if(name.equalsIgnoreCase("admin"))
                {
                logger.info("Admin found with details="+user);
                HttpSession session = request.getSession();
                session.setAttribute("User", user);
                response.sendRedirect("admin.jsp");
                }

            }else{
                RequestDispatcher rd = getServletContext().getRequestDispatcher("/login.html");
                PrintWriter out= response.getWriter();
                logger.error("User not found with email="+email);
                out.println("<font color=red>No user found with given email id, please register first.</font>");
                rd.include(request, response);
            }
        } catch (SQLException e) {
            e.printStackTrace();
            logger.error("Database connection problem");
            throw new ServletException("DB Connection problem.");
        }finally{
            try {
                rs.close();
                ps.close();
            } catch (SQLException e) {
                logger.error("SQLException in closing PreparedStatement or ResultSet");;
            }

        }
        }

针对home.jsp

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@page import="com.javadbproject.util.User"%>
<%@ page language="java" contentType="text/html; charset=US-ASCII"
    pageEncoding="US-ASCII"%>
<!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=US-ASCII">
<title>Home Page</title>

<link rel="stylesheet" type="text/css" href="<c:url value='/loginstyle.css'/>"> 

</head>
<body>
<%User user = (User) session.getAttribute("User"); %>
<h3>Hi <%=user.getName() %></h3>
<strong>Your Email</strong>: <%=user.getEmail() %><br>
<strong>Your Country</strong>: <%=user.getCountry() %><br>
<br>
<form action="Logout" method="post">
<input type="submit" value="Logout" >

</form>
</body>
</html>

AuthenticationServlet

package com.javadbproject.servlet.filters;


import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.log4j.Logger;

@WebFilter("/AuthenticationFilter")
public class AuthenticationFilter implements Filter {

    private Logger logger = Logger.getLogger(AuthenticationFilter.class);

    public void init(FilterConfig fConfig) throws ServletException {
        logger.info("AuthenticationFilter initialized");
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;

        String uri = req.getRequestURI();
        logger.info("Requested Resource::"+uri);

        HttpSession session = req.getSession(false);

        if(session == null && !(uri.endsWith("html") || uri.endsWith("Login") || uri.endsWith("Register"))){
            logger.error("Unauthorized access request");
            res.sendRedirect("login.html");
        }else{
            // pass the request along the filter chain
            chain.doFilter(request, response);
        }


    }

    public void destroy() {
        //close any resources here
    }

}

我希望在与home.jsp

类似的行上开发我的admin.jsp

谢谢！

Answer 1

首先需要一个数据库mysql。
您需要mysql connector jar file。

例如，创建class User。

public class User{
   String iduser;
   String name;
   String username;
   String password;

   //setters and getters
}

在mysql或您拥有的任何数据库中为用户创建一个表。

CREATE TABLE sampleapplication。user（ iduser INT NOT NULL AUTO_INCREMENT， name VARCHAR（45）NULL， username VARCHAR（45）NULL， usercol VARCHAR（45）NULL， PRIMARY KEY（iduser））;
让我们开始database with java。 :)在构建路径(right click project > Build path > Configure build path > Click Add external jar > Locate mysql connector)中添加mysql连接器jar文件，并将其粘贴到web-inf>lib文件夹中。

创建class for database transaction。 reference

public class DatabaseTransaction{

   public List<User> readDataBase() throws Exception {
     try {
        // this will load the MySQL driver, each DB has its own driver
        Class.forName("com.mysql.jdbc.Driver");
        // setup the connection with the DB.
        connect = DriverManager
          .getConnection("jdbc:mysql://localhost/database?"
               + "user=sqluser&password=sqluserpw");

        // statements allow to issue SQL queries to the database
        statement = connect.createStatement();
        // resultSet gets the result of the SQL query
        resultSet = statement
             .executeQuery("select * from user");

        List<User> listOfUsers=new ArrayList<User>();
         User userToAdd;

        while (resultSet.next()) {
            userToAdd = new User();
            userToAdd.setUsername(resultSet.getString("username"));
            userToAdd.setPassword(resultSet.getString("pword"));
            userToAdd.setUserid(resultSet.getString("userid"));
            userToAdd.setName(resultSet.getString("name"));
            listOfUsers.add(userToAdd);
        }
    }
  }

致电DatabaseTransaction致filter/controller/servlet

DatabaseTransaction databaseTransaction = DatabaseTransaction();

//use your `HttpServletRequest`
//parameters are key and value
//store as attribute to access in jsp page
request.setAttribute("userList",databaseTransaction.readDataBase());

//then forward the page using `HttpServletRequest` 
//dont use response.redirect(); you wont be able to use the attribute because you are using a response 
//filename of the jsp
request.getRequestDispatcher("adminpage").forward(request, response);

在您的jsp页面中。使用JSTL

 //import the core tag library
  <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

  //lastly loop through the list attribute
   <table>
     <thead>
       <tr>
         <td>id</td>
         <td>Name</td>
         <td>Username</td>
       </tr>
     </thead>

     <tbody>
        <c:foreach items="${userList}" var="user">
          <tr>
             <td><c:out value="${user.iduser}"/></td>
             <td><c:out value="${user.name}"/></td>
             <td><c:out value="${user.username}"/></td>
          </tr>
        </c:foreach>
    </tbody>
  </table>

多数民众赞成：）

Answer 2

Servlet Filter是您所需要的，您需要为每个用户创建逻辑角色，并为每个角色配置允许的URL模式，并根据过滤过滤每个请求和阻止/允许

有关使用jsp创建管理页面的建议

2 个答案: