【发布时间】：2015-11-23 10:22:02
【问题描述】：
我正在尝试从教程创建 CRUD 应用程序，但我在 AllPost.jsp 中遇到了没有错误的问题，它只显示没有数据的元素的标题，我检查了我的 mysql 数据库，它没有插入任何东西 这是我的代码
AllPost.jsp
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<title>JSP Page</title>
</head>
<body>
<div style="width: 1200px; margin-left: auto; margin-right: auto">
<table cellpadding="10">
<tr>
<th>Id</th>
<th>Title</th>
<th>Description</th>
<th>Detail</th>
<th>Category</th>
<th>Date</th>
<th>Image</th>
<th></th>
</tr>
<c:forEach items="${AllPost}" var="p">
<tr>
<td>${p.id}</td>
<td>${p.title}</td>
<td>${p.description}</td>
<td>${p.detail}</td>
<td>${p.category}</td>
<td>${p.date}</td>
<td>${p.image}</td>
<td>
<a href="edit?id=${p.id}">Edit</a>
<a href="delete?id=${p.id}">Delete</a>
</td>
</tr>
</c:forEach>
</table>
</div>
</body>
</html>
AllPost.java
package servlet;
import dao.DataAccess;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(name="AllPost", urlPatterns={"/AllPost"})
public class AllPost extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException, SQLException {
request.setAttribute("AllPost", DataAccess.getAll());
RequestDispatcher rd = request.getRequestDispatcher("AllPost.jsp");
rd.forward(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// processRequest(request, response);
request.setAttribute("AllPost", DataAccess.getAll());
RequestDispatcher rd = request.getRequestDispatcher("AllPost.jsp");
rd.forward(request, response);
}
}
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
id="WebApp_ID"
version="3.0">
<servlet>
<servlet-name>AllPost</servlet-name>
<jsp-file>/AllPost.jsp</jsp-file>
</servlet>
<servlet-mapping>
<servlet-name>AllPost</servlet-name>
<url-pattern>/AllPost</url-pattern>
</servlet-mapping>
<session-config>
<session-timeout>
30
</session-timeout>
</session-config>
<welcome-file-list>
<welcome-file>AddNew.html</welcome-file>
</welcome-file-list>
</web-app>
DataAccess.java
package dao;
public class DataAccess {
public void addNew(News n){
try {
PreparedStatement ps = DButil.getPreparedStatement("insert into news values(?,?,?,?,?,?)");
ps.setString(1,n.getTitle());
ps.setString(2,n.getDate());
ps.setString(3,n.getDescription());
ps.setString(4,n.getDetail());
ps.setString(5,n.getCategory());
ps.setString(6,n.getImage());
ps.executeUpdate();
} catch (ClassNotFoundException ex) {
Logger.getLogger(DataAccess.class.getName()).log(Level.SEVERE, null, ex);
} catch (SQLException ex) {
Logger.getLogger(DataAccess.class.getName()).log(Level.SEVERE, null, ex);
}
}
public static List<News> getAll() {
List<News> ls = new LinkedList<News>();
try {
ResultSet rs = DButil.getPreparedStat ement("select * from news").executeQuery();
} catch (ClassNotFoundException ex) {
Logger.getLogger(DataAccess.class.getName()).log(Level.SEVERE,null,ex);
}catch (SQLException ex){
Logger.getLogger(DataAccess.class.getName()).log(Level.SEVERE,null,ex);
}
return ls;
}
}
和 DButil.java
package db;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.PreparedStatement;
import java.sql.DriverManager;
import java.sql.SQLException;
public class DButil {
public static PreparedStatement getPreparedStatement(String sql) throws ClassCastException, ClassNotFoundException, SQLException{
PreparedStatement ps=null;
Class.forName("com.mysql.jdbc.Driver");
String url="jdbc:mysql://localhost/crud";
String user="root";
String password="";
Connection con= (Connection) DriverManager.getConnection (url, user, password);
ps=(PreparedStatement) con.prepareStatement(sql);
return ps;
}
}
ManagerAddNew.jsp
<%@page import="dao.DataAccess"%>
<%@page import="model.News"%>
<%@page import="java.text.SimpleDateFormat"%>
<%@page import="java.sql.Date"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!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>JSP Page</title>
</head>
<body>
<%
String title=request.getParameter("title");
Date dateTmp = new Date(System.currentTimeMillis());
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd");
String date = dateFormat.format(dateTmp.getTime());
String description=request.getParameter("description");
String detail=request.getParameter("detail");
String category=request.getParameter("category");
String image=request.getParameter("image");
News n = new News(0, title, date, description, detail, category, image);
DataAccess da = new DataAccess();
da.addNew(n);
response.sendRedirect("/CRUD_NEWS/AllPost");
%>
</body>
</html>
【问题讨论】：
-
为什么要抓
ClassNotFoundException？ -
netbeans 强迫我这样做
-
那是因为你把它扔进
DBUtil类。
标签： mysql jsp jakarta-ee servlets