尝试从数据库中获取对象列表时获取重复的最后一个表单数据的列表

Question

我的第一个 jsp 是 email.jsp，从那里指向 template.jsp 但是当我尝试获取 EmailMessages 对象的列表时，我得到了最后一个表单的重复条目提交数据的时候我必须获取数据库中的所有对象。谁能帮我解决这个问题？

@RequestMapping(value = "/email", method = RequestMethod.GET)
public String addEmail() {
    return "email";
}

@RequestMapping(value = "/template", method = RequestMethod.POST)
public String getTemplateEmail(@ModelAttribute EmailMessage emailMessage, ModelMap model) {
    emailService.insertTemplate(emailMessage);
    List<EmailMessage> emailMessageList = new ArrayList<EmailMessage>();
    emailMessageList = emailService.fetchTemplate();
    model.addAttribute("emailMessageList", emailMessageList);
    return "template";
}

email.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
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>Email body</title>
</head>
<body>
<form action="/TemplateEmail/template" method="POST">
<table>
    <tr>
        <td><b>Category </b>: </td>
        <td><select name="category">
            <option value=""> </option>
            <option value="normal">Normal</option>
            <option value="urgent">Urgent</option>
        </select></td>
        <td>
        <button type="button" style="width: 25px;height: 25px;border: solid 1px #000;border-radius: 25px" onclick="addCategory()">+</button>
        <script>
            function addCategory() {
                var category = prompt("Add new category", "");
            }
        </script>
        </td>
    </tr>
    <tr>
        <td><b>Subject </b>: </td>
        <td><input type="text" name="subject"/></td>
    </tr>
    <tr>
        <td><b>Body </b>: </td>
        <td><textarea name="body" rows="10" columns="50"></textarea>     </td>
    </tr>
    <tr>
        <td colspan="2" align="center">
        <input type="submit" value=" SAVE "/>
        </td>
    </tr>
</table>
</form>
</body>
</html>

EmailMessage.java

package com.qburst.templateemail.entity;

public class EmailMessage {

private String category;
private String subject;
private String body;
private Long id;

public String getCategory() {
    return category;
}

public void setCategory(String category) {
    this.category = category;
}

public String getSubject() {
    return subject;
}

public void setSubject(String subject) {
    this.subject = subject;
}

public String getBody() {
    return body;
}

public void setBody(String body) {
    this.body = body;
}

public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

}

template.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!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>Template Webpage</title>
</head>
<body>
<center>
    <table border="1">
      <tr>
        <th>select</th>
        <th>Category</th>
        <th>Subject</th>
        <th>Body</th>
      </tr>
      <c:forEach var="emailMessage" items="${emailMessageList}">
          <tr>
            <td><label for="${emailMessage.id}"></label><input type="radio" name="emailMsg" id="${emailMessage.id}"/></td>
            <td>${emailMessage.category}</td>
            <td>${emailMessage.subject}</td>
            <td>${emailMessage.body}</td>
          </tr>
      </c:forEach>
    </table><br>
    <input type="button" onclick="location.href='/TemplateEmail/email'" value="Add More" />
    <br><br><br>
    <input type="button" onclick="location.href='/TemplateEmail/send_email'" value="Send To" />
    </center>
  </body>
</html>

EmailDao.java 这是从数据库中获取列表的代码。

public List<EmailMessage> fetchTemplate() {
    String query = "select * from email_message";
    Connection connection = null;
    List<EmailMessage> emailMessageList = new ArrayList<EmailMessage>();
    try {
        EmailMessage emailMessage = new EmailMessage();
        connection = dataSource.getConnection();
        PreparedStatement preparedStatement = connection.prepareStatement(query);
        ResultSet resultSet = preparedStatement.executeQuery(query);
        while (resultSet.next()) {
            emailMessage.setCategory(resultSet.getString("category"));
            emailMessage.setSubject(resultSet.getString("subject"));
            emailMessage.setBody(resultSet.getString("body"));
            emailMessageList.add(emailMessage);
        }
    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    return emailMessageList;
}

Answer 1

好的，尝试在循环中始终创建新对象：

EmailMessage emailMessage;
while (resultSet.next()) {
       emailMessage = new EmailMessage();
       emailMessage.setCategory(resultSet.getString("category"));
       emailMessage.setSubject(resultSet.getString("subject"));
       emailMessage.setBody(resultSet.getString("body"));
       emailMessageList.add(emailMessage);
}

您被重复 link 添加到要列出的对象。您总是更改列表所有成员的值，因为它 link 到一个对象。

尝试从数据库中获取对象列表时获取重复的最后一个表单数据的列表

Getting a list of the repeated last form data when trying to fetch the list of objects from database

java

jsp

controller

spring-mvc

modelattribute