我的任务：我必须从jsp视图的每一行删除对“testtable”表的操作。
我的问题：在删除行时无法获取表ID。
使用的应用技术： jsp作为视图，servlet作为控制器，setter和getter方法作为模型，jdbc代码用于数据库操作。
后端mysql ：=我有两个表一个“userinfo”用于aurtherntication，另一个表“testtable”。
对于两个表连接，我在jsp中使用了隐藏字段输入，而不是使用外键关系。
在控制台打印中，我们可以在点击删除按钮后看到 com.mysql.jdbc.JDBC4PreparedStatement@1f4bcaf：从testtable中删除id = 0和email='myswagt@yahoo.com' 在家servlet userid为0
请根据jsp，servlet，model，jdbc帖子帮助我：
//费用模型
package com.intermediateDemo.home.dto;
public class ItemBean {
private int id;
private String email;
private String itemName;
private Double itemPrice;
private String transactionTime;
private int userid;
public ItemBean() {
}
public ItemBean(int id, String email, String itemName, Double itemPrice, String transactionTime) {
this.id = id;
this.itemName = itemName;
this.itemPrice = itemPrice;
this.transactionTime = transactionTime;
this.email = email;
}
public String toString() {
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.append("\n----------------------------------------------------------------------------------------------\n");
stringBuilder.append("Id: " + id);
//stringBuilder.append("\tName: " + firstName + ' ' + middleName + ' ' + lastName);
stringBuilder.append("\titemname: " + itemName);
stringBuilder.append("\titemprice: " + itemPrice);
stringBuilder.append("\ttime: " + transactionTime);
stringBuilder.append("\n----------------------------------------------------------------------------------------------\n");
return stringBuilder.toString();
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public int getUserid() {
return userid;
}
public void setUserid(int userid) {
this.userid = userid;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getItemName() {
return itemName;
}
public void setItemName(String itemName) {
this.itemName = itemName;
}
public Double getItemPrice() {
return itemPrice;
}
public void setItemPrice(Double itemPrice) {
this.itemPrice = itemPrice;
}
public String getTransactionTime() {
return transactionTime;
}
public void setTransactionTime(String transactionTime) {
this.transactionTime = transactionTime;
}
}
//用户模型
package com.intermediateDemo.login.dto;
public class LoginBean {
private int userid;
private String email;
private String password;
public boolean valid;
private String lastName;
private String firstName;
public LoginBean() {
}
public LoginBean(String email, String lastname, String firstname) {
this.email = email;
this.firstName = firstname;
this.lastName = lastname;
}
public int getUserid() {
return userid;
}
public void setUserid(int userid) {
this.userid = userid;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public boolean isValid() {
return valid;
}
public void setValid(boolean valid) {
this.valid = valid;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getLastName() {
return lastName;
}
public String getFirstName() {
return firstName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
}
//删除servlet
package com.intermediateDemo.home.controller;
import com.intermediateDemo.home.dao.ItemDao;
import com.intermediateDemo.home.dao.ItemDaoFactory;
import com.intermediateDemo.home.dto.ItemBean;
import com.intermediateDemo.login.dto.LoginBean;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class DeleteExpense extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws NumberFormatException, ServletException, IOException {
ItemBean item = new ItemBean() ;
try {
ItemDao dao = ItemDaoFactory.getItemDao();
HttpSession session = request.getSession(false);
LoginBean user = (LoginBean) session.getAttribute("user");
item.setId(Integer.parseInt(request.getParameter("id")));
item.setEmail(user.getEmail());
dao.deleteItem(item, user);
} catch (Exception e) {
e.printStackTrace();
}
finally {
response.sendRedirect("homeservlet");
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
RequestDispatcher view;
view = request.getRequestDispatcher("/home/home.jsp");
view.forward(request,response);
}
}
// jdbc代码
public void deleteItem(ItemBean item, LoginBean user) throws Exception {
try {
JdbcConnection connection = new JdbcConnection();
String query = "delete from testtable where id=? and email=?";
Connection con = connection.getConnection();
PreparedStatement pstm = con.prepareStatement(query);
pstm.setInt(1, item.getId());
pstm.setString(2, user.getEmail());
System.out.println(pstm);
pstm.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
throw e;
}
}
// jsp视图
<%--
Created by IntelliJ IDEA.
User: Dell
Date: 3/13/14
Time: 8:12 PM
To change this template use File | Settings | File Templates.
--%>
<%@ page import="com.intermediateDemo.home.dto.ItemBean" %>
<%@ page import="java.util.List" %>
<%@ page import="com.intermediateDemo.login.dto.LoginBean" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>home</title>
<link rel="stylesheet" type="text/css" href="style_css/mystylesheet.css">
<link rel=”stylesheet” href=”resource/css/bootstrap.css” type=”text/css”/>
</head>
<body>
<jsp:include page="../includes/header.jsp"/>
<div id="content" style="margin-left: 330px;margin-bottom: 10px">
Welcome <%=session.getAttribute("email")%>
your id is <%=session.getAttribute("userid")%>
your firstname is <%=session.getAttribute("firstname")%>
<h2>Your Financial Management</h2>
<form action="homeservlet" method="post">
<!--start display-->
<legend>
<h2>Expense list</h2>
</legend>
<div>
<table class="table table-bordered table-striped" style="padding- left:200px;border:2px;border-bottom-color: limegreen">
<thead>
<tr style="background: limegreen">
<th >Expense title</th>
<th>Expense amount</th>
<th>Expense Date</th>
</tr>
</thead>
<tbody>
<c:forEach var="item" items="${requestScope.itemList}" >
<tr style="background:#808080;color:#ffffff">
<td><c:out value="${item.getItemName()}"> </c:out></td>
<td><c:out value="${item.getItemPrice()}"> </c:out></td>
<td><c:out value="${item.getTransactionTime()}"> </c:out></td>
<td>
<form method="post" action="/deleteexpense">
<input type="hidden" name="id" value="${item.id}">
<input class="btn btn-mini btn-danger " type="submit" value="Delete"/>
<a class="btn btn-mini " href="edit?id=${item.id}">Edit</a>
</form>
</td>
</tr>
</c:forEach>
</tbody>
</table>
</div>
</form>
</div>
<jsp:include page="../includes/footer.jsp"/>
</body>
</html>
// DAO，我检索ItemBean的数据
public List<ItemBean> getItemFromdb(LoginBean user) throws SQLException {
List<ItemBean> itemList = new ArrayList<ItemBean>();
JdbcConnection connecton = new JdbcConnection();
//String query = "select * from testtable where userid = ?";
String query = "select * from testtable where email = ?";
ResultSet rs;
try {
Connection con = connecton.getConnection();
PreparedStatement pstm = con.prepareStatement(query);
// pstm.setInt(1, user.getUserid());
pstm.setString(1,user.getEmail());
rs = pstm.executeQuery();
while (rs.next()) {
ItemBean item = new ItemBean();
item.setItemName(rs.getString("itemname"));
item.setItemPrice(rs.getDouble("itemprice"));
item.setTransactionTime(rs.getString("transactiontime"));
// item.setUserid(rs.getInt("userid"));
item.setEmail(rs.getString("email"));
itemList.add(item);
}
System.out.println("at jdbc code");
for (ItemBean item1 : itemList) {
System.out.println(item1.getItemName());
System.out.println(item1.getItemPrice());
System.out.println(item1.getTransactionTime());
}
} catch (SQLException e) {
e.printStackTrace();
}
return itemList;
}
//在一个页面中插入，检索和删除类似操作的jdbc代码
package com.intermediateDemo.home.dao.mysql;
import com.intermediateDemo.common.JdbcConnection;
import com.intermediateDemo.home.dto.ItemBean;
import com.intermediateDemo.login.dto.LoginBean;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
public class JdbcItemMysql {
public void itemtodb(ItemBean item, LoginBean user) throws Exception {
JdbcConnection connection = new JdbcConnection();
//String query = "insert into testtable (itemname,itemprice,transactiontime,userid) values (?,?,?,?)";
String query = "insert into testtable (itemname,itemprice,transactiontime,email) values (?,?,?,?)";
try {
Connection con = connection.getConnection();
PreparedStatement pstm = con.prepareStatement(query);
pstm.setString(1, item.getItemName());
pstm.setDouble(2, Double.parseDouble(String.valueOf(item.getItemPrice())));
pstm.setString(3, item.getTransactionTime());
pstm.setString(4, user.getEmail());
// pstm.setInt(4,user.getId());
pstm.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
throw e;
}
}
public List<ItemBean> getItemFromdb(LoginBean user) throws SQLException {
List<ItemBean> itemList = new ArrayList<ItemBean>();
JdbcConnection connecton = new JdbcConnection();
//String query = "select * from testtable where userid = ?";
String query = "select * from testtable where email = ?";
ResultSet rs;
try {
Connection con = connecton.getConnection();
PreparedStatement pstm = con.prepareStatement(query);
// pstm.setInt(1, user.getUserid());
pstm.setString(1,user.getEmail());
rs = pstm.executeQuery();
while (rs.next()) {
ItemBean item = new ItemBean();
item.setItemName(rs.getString("itemname"));
item.setItemPrice(rs.getDouble("itemprice"));
item.setTransactionTime(rs.getString("transactiontime"));
// item.setUserid(rs.getInt("userid"));
item.setEmail(rs.getString("email"));
itemList.add(item);
}
System.out.println("at jdbc code");
for (ItemBean item1 : itemList) {
System.out.println(item1.getItemName());
System.out.println(item1.getItemPrice());
System.out.println(item1.getTransactionTime());
}
} catch (SQLException e) {
e.printStackTrace();
}
return itemList;
}
public void deleteItem(ItemBean item, LoginBean user) throws Exception {
try {
JdbcConnection connection = new JdbcConnection();
String query = "delete from testtable where id=? and email=?";
Connection con = connection.getConnection();
PreparedStatement pstm = con.prepareStatement(query);
pstm.setInt(1, item.getId());
pstm.setString(2, user.getEmail());
System.out.println(pstm);
pstm.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
throw e;
}
}
答案 0 :(得分：0)
您没有从您的方法将记录ID传递给jsp页面。你的getItemFromdb（）应该是这样的东西
public List<ItemBean> getItemFromdb(LoginBean user) throws SQLException {
// whatever you are doing comes here
while (rs.next()) {
ItemBean item = new ItemBean();
item.setId(rs.getInt("id"); // you need to have this, here id is the the primary key of the table
item.setItemName(rs.getString("itemname"));
item.setItemPrice(rs.getDouble("itemprice"));
item.setTransactionTime(rs.getString("transactiontime"));
// item.setUserid(rs.getInt("userid"));
item.setEmail(rs.getString("email"));
itemList.add(item);
}
// rest of the code
}
这样在jsp页面中你可以使用这个id来识别记录做你想做的任何操作