java - 使用选择选项标签从Java中的数据库中检索记录-6ren

java - 使用选择选项标签从Java中的数据库中检索记录

转载作者：行者123 更新时间：2023-12-01 09:47:09

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4

我想通过单击从下拉列表中选择的选项并将其作为网页上的表格来从数据库中检索记录。但是执行以下代码后，网页现在是空白的，我该怎么办？任何类型的帮助都将是值得赞赏的。这是我的 index.jsp 页面:

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <form name="f1" action="portal" method="POST">
            <h3>Name of the Book : </h3>
                <select name="book" id="book">
                    <option value="">Select</option>
                    <option value="1">The Pilgrims Progress</option>
                    <option value="2">Robinson Crusoe</option>
                    <option value="3">Gullivers Travels</option>
                    <option value="4">Clarissa</option>
                    <option value="5">Tom Jones</option>
                    <option value="6">The Life and Opinions of Tristram Shandy, Gentleman</option>
                    <option value="7">Emma</option>
                    <option value="8">Frankenstein</option>
                    <option value="9">Nightmare Abbey</option>
                    <option value="10">The Narrative of Arthur Gordon Pym of Nantucket</option>
                    <option value="11">Sybil</option>
                    <option value="12">Jane Eyre</option>
                    <option value="13">Wuthering Heights</option>
                    <option value="14">Vanity Fair</option>
                    <option value="15">David Copperfield</option>
                    <option value="16">The Scarlet Letter</option>
                    <option value="17">Moby-Dick</option>
                    <option value="18">Alices Adventures in Wonderland</option>
                    <option value="19">The Moonstone</option>
                    <option value="20">Little Women</option>
                    <option value="21">Middlemarch</option>
                </select>
            <input type="submit" value="submit" />
        </form>
    </body>
</html>

这是我的 servlet 页面，用于从数据库检索数据

package com;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class portal extends HttpServlet {

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request
     *            servlet request
     * @param response
     *            servlet response
     * @throws ServletException
     *             if a servlet-specific error occurs
     * @throws IOException
     *             if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            String book = request.getParameter("book");
            Class.forName("com.mysql.jdbc.Driver");
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql", "root", "password");
            PreparedStatement pt = conn.prepareStatement("Select * from book where Book_Name = ?");
            pt.setString(1, book);
            out.print("<table width = 75%>");
            out.print("<center><h1>Welcome To The Portal</h1></center>");
            ResultSet rs = pt.executeQuery();
            ResultSetMetaData rsd = rs.getMetaData();
            while (rs.next()) {
                out.print("<tr>");
                out.print("<td>" + rsmd.getColumnName(1) + "</td>");
                out.print("<td>" + rs.getString(1) + "</td></tr>");
                out.print("<tr><td>" + rsmd.getColumnName(2) + "</td>");
                out.print("<td>" + rs.getString(2) + "</td></tr>");
                out.print("<tr><td>" + rsmd.getColumnName(3) + "</td>");
                out.print("<td>" + rs.getString(3) + "</td></tr>");
                out.print("<tr><td>" + rsmd.getColumnName(4) + "</td>");
                out.print("<td>" + rs.getString(4) + "</td></tr>");
                RequestDispatcher rd = request.getRequestDispatcher("logout.jsp");
                rd.include(request, response);
            }
            out.println("</table>");
        }

        catch (Exception e) {
            out.println(e);
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the
    // + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request
     *            servlet request
     * @param response
     *            servlet response
     * @throws ServletException
     *             if a servlet-specific error occurs
     * @throws IOException
     *             if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request
     *            servlet request
     * @param response
     *            servlet response
     * @throws ServletException
     *             if a servlet-specific error occurs
     * @throws IOException
     *             if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

}

现在我不知道我在哪里错过了一些东西。

最佳答案

我建议您使用 servlet 作为控制应用程序中数据的 Controller ，而不是作为编写 html 标签的 vue

这个例子可能对你有帮助:

首先，创建一个可序列化的java类，在其中与数据库进行通信:

public class BookData implements Serializable {

    private String ISBN;
    private String titre;
    private String auteur;
    private int ID;
    private String editeur;

    // ADD GETTER AN SETTER METHODS

    public BookData(String titre, String auteur, int ID, String editeur, String ISBN) {
        this.titre = titre;
        this.auteur = auteur;
        this.ID = ID;
        this.editeur = editeur;
        this.ISBN = ISBN;
    }

    public List<BookData> loadData(String book) {
        List<BookData> actorList = new ArrayList<BookData>();

        com.mysql.jdbc.PreparedStatement ps = null;

        ResultSet rs = null;

        String url = "jdbc:mysql://127.0.0.1:3306/DATABASENAME";// CHANGE
        String name = "NAME";// CHANGE
        String pw = "PWD";// CHANGE
        String driver = "com.mysql.jdbc.Driver";

        Connection connexion = null;

        try {
            Class.forName(driver).newInstance();
            connexion = DriverManager.getConnection(url, name, pw);

            String q = "Select * from book where Book_Name ='" + book + "'";
            Statement commande = connexion.createStatement();
            rs = commande.executeQuery(q);

            while (rs.next()) {
                BookData bk = new BookData(rs.getString("Book_Title"), rs.getString("Book_Author"), rs.getInt("ID"),
                        rs.getString("Publisher"), rs.getString("ISBN"));/* CHANGE COLUMN NAMES */

                actorList.add(bk);
            }

            return actorList;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        } finally {
            try {
                rs.close();
                connexion.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

其次是 servlet:

public class EXAMPLE_SERVLET extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        String option = request.getParameter("book");

        BookData dao = new BookData();
        List<BookData> list = dao.loadData(option);

        request.setAttribute("booklist", list);

        RequestDispatcher view = request.getRequestDispatcher("test.jsp");
        view.forward(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

    }
}

然后是 JSP ((test.jsp))

<table>
    <thead>
        <tr>
            <th>titre</th> //...COLUMNS
        </tr>
    </thead>
    <tbody>
        <c:forEach var="employee" items="${booklist}">
            <tr>
                <td style="width: 110px; color: #3278b3;">${employee.titre}</td>
                //...ROWS
            </tr>
        </c:forEach>
    </tbody>
</table>

关于java - 使用选择选项标签从Java中的数据库中检索记录，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37895917/

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java - 使用选择选项标签从Java中的数据库中检索记录

标签)？
根据 Web 标准，创建带有标题 1 的链接的正确代码是什么？是吗 stackoverflow 或 stackoverflow 谢谢最佳答案根据网络标准，您不能将 block 元素放入内

首页

博学

6Ren·AI

商城

java - 使用选择选项标签从Java中的数据库中检索记录

标签)？ 根据 Web 标准，创建带有标题 1 的链接的正确代码是什么？ 是吗 stackoverflow 或 stackoverflow 谢谢 最佳答案 根据网络标准，您不能将 block 元素放入内

标签)？
根据 Web 标准，创建带有标题 1 的链接的正确代码是什么？是吗 stackoverflow 或 stackoverflow 谢谢最佳答案根据网络标准，您不能将 block 元素放入内