Use Java to write form data display and browsing functions

Use Java to write form data display and browsing functions

Overview:
In Web development, forms are a very common data input method. In many scenarios, we need to display submitted form data so that users can view and browse. This article will guide you to use Java to write a simple form data display and browsing function.

Implementation steps:

1. Create database table
   First, we need to create a table in the database to store form data. Assume that the table we create is named "form_data" and contains the following fields: id (auto-incrementing primary key), name (name), age (age), email (mailbox).
2. Create Java class
   Next, create a class named "FormData" in Java to represent form data. This class should contain fields corresponding to those in the database table and provide corresponding setter and getter methods.

Sample code:

public class FormData {
    private int id;
    private String name;
    private int age;
    private String email;

    // 构造方法
    public FormData(int id, String name, int age, String email) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.email = email;
    }

    // setter和getter方法
    public void setId(int id) {
        this.id = id;
    }

    public int getId() {
        return id;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getAge() {
        return age;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getEmail() {
        return email;
    }
}

3. Write data access layer code
   Next, we need to write data access layer code for interacting with the database and obtaining the form data. Suppose we use JDBC to connect and operate with the database.

Sample code:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

public class FormDataDAO {
    private static final String DB_URL = "jdbc:mysql://localhost:3306/mydb";
    private static final String DB_USER = "root";
    private static final String DB_PASSWORD = "password";

    public List<FormData> getAllFormData() {
        List<FormData> formDataList = new ArrayList<>();

        try {
            // 连接数据库
            Connection conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);
            // 执行查询语句
            String sql = "SELECT * FROM form_data";
            PreparedStatement statement = conn.prepareStatement(sql);
            ResultSet rs = statement.executeQuery();

            // 遍历结果集，将数据封装为FormData对象
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                int age = rs.getInt("age");
                String email = rs.getString("email");

                FormData formData = new FormData(id, name, age, email);
                formDataList.add(formData);
            }

            // 关闭数据库连接
            rs.close();
            statement.close();
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return formDataList;
    }
}

4. Create Servlet
   Finally, we need to create a Servlet class to receive client requests and call the data access layer code, Get form data. Then, pass the form data to the view layer for display.

Sample code:

import java.io.IOException;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class FormViewServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 调用数据访问层代码，获取表单数据
        FormDataDAO formDataDAO = new FormDataDAO();
        List<FormData> formDataList = formDataDAO.getAllFormData();

        // 将表单数据传递给视图层进行展示
        request.setAttribute("formDataList", formDataList);
        request.getRequestDispatcher("form_view.jsp").forward(request, response);
    }
}

5. Create JSP view
   Finally, we need to create a JSP view named "form_view.jsp" in the WEB-INF directory File used to display form data. In this JSP file, we can use the JSTL tag library to traverse and display the form data.

Sample code:

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>表单数据展示</title>
</head>
<body>
    <table>
        <tr>
            <th>ID</th>
            <th>姓名</th>
            <th>年龄</th>
            <th>邮箱</th>
        </tr>
        <c:forEach var="formData" items="${formDataList}">
            <tr>
                <td>${formData.id}</td>
                <td>${formData.name}</td>
                <td>${formData.age}</td>
                <td>${formData.email}</td>
            </tr>
        </c:forEach>
    </table>
</body>
</html>

Summary:
Through the above steps, we can use Java to write a simple form data display and browsing function. Create a FormData class to represent the form data, then write the data access layer code to interact with the database, and finally pass the form data to the JSP view for display. In this way, users can easily view and browse submitted form data.

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