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从数据库中检索记录。但是在实现以下代码之后，网页现在是空白的，我该怎么办？任何类型的帮助都会很明显。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>
这是我的servlet页面，用于从数据库中检索数据
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>
}
现在我不知道我错过了什么。
答案 0 :(得分：1)
我建议您使用servlet作为控制器来控制应用程序中的数据，而不是用作编写html标签的vue
这个例子可以帮到你：
首先，创建一个可序列化的java类，用于与数据库进行通信：
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 {
}
}
<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>
答案 1 :(得分：0)
我解决了我的问题，感谢所有帮助过我的人，但不是我得到了我在哪里做了一个错误，它在选项标签值属性我把值取为1,2和3 ......所以但它应该是相同的作为文本和servlet页面我已经将while循环更改为if＆amp;所以它工作得很好..非常感谢你的帮助