How to develop a simple online mall system using MySQL and Java

How to use MySQL and Java to develop a simple online mall system

With the development of the Internet, e-commerce has become one of the main ways for people to shop. As the core component of e-commerce, the online mall system is of great significance to both merchants and consumers. This article will introduce how to use MySQL and Java to develop a simple online mall system, and provide specific code examples.

To develop an online mall system, you first need to build a database to store product information, user information, order information, etc. In this article, we choose to use MySQL as the database management system. First, you can create a database to store relevant data, such as "shop". Then you can create multiple tables in the database, such as "products" to store product information, "users" to store user information, "orders" to store order information, etc. The following are specific code examples for creating these three tables:

Create product table:
CREATE TABLE products (

id INT PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(100) NOT NULL,
price DECIMAL(10, 2) NOT NULL,
description TEXT,
image VARCHAR(200) DEFAULT NULL

);

Create user table:
CREATE TABLE users (

id INT PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(100) NOT NULL,
email VARCHAR(100) NOT NULL UNIQUE,
password VARCHAR(100) NOT NULL

);

Create order table:
CREATE TABLE orders (

id INT PRIMARY KEY AUTO_INCREMENT,
user_id INT NOT NULL,
product_id INT NOT NULL,
quantity INT NOT NULL,
total_price DECIMAL(10, 2) NOT NULL,
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
FOREIGN KEY (user_id) REFERENCES users(id),
FOREIGN KEY (product_id) REFERENCES products(id)

);

With database Basics, the next step is to use Java to write back-end code to connect to the database and implement various functions of the online mall system. In Java, you can use the JDBC API to connect to the MySQL database.

First you need to import the MySQL JDBC driver into the Java project, usually a .jar file. You can copy this file to the project's lib folder and add a reference to the library in the IDE.

Next, you can write a class named "DatabaseConnection" to establish a connection with the MySQL database. The following is a code example for this class:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DatabaseConnection {

private static final String URL = "jdbc:mysql://localhost:3306/shop";
private static final String USERNAME = "root";
private static final String PASSWORD = "123456";

public static Connection getConnection() throws SQLException {
    return DriverManager.getConnection(URL, USERNAME, PASSWORD);
}

}

The above code uses the default connection configuration of MySQL. If your MySQL database uses a different port or password, you need to make corresponding modifications.

After you have a database connection, you can write other business logic codes to implement the functions of the online mall system, such as product list display, user registration and login, shopping cart management, etc. The following is some sample code:

Get the product list:
public List getProductList() {

List<Product> products = new ArrayList<>();
try (Connection conn = DatabaseConnection.getConnection();
     Statement stmt = conn.createStatement();
     ResultSet rs = stmt.executeQuery("SELECT * FROM products")) {
    while (rs.next()) {
        Product product = new Product();
        product.setId(rs.getInt("id"));
        product.setName(rs.getString("name"));
        product.setPrice(rs.getDouble("price"));
        product.setDescription(rs.getString("description"));
        product.setImage(rs.getString("image"));
        products.add(product);
    }
} catch (SQLException e) {
    e.printStackTrace();
}
return products;

}

User registration:
public boolean register(User user) {

boolean success = false;
try (Connection conn = DatabaseConnection.getConnection();
     PreparedStatement stmt = conn.prepareStatement("INSERT INTO users (name, email, password) VALUES (?, ?, ?)")) {
    stmt.setString(1, user.getName());
    stmt.setString(2, user.getEmail());
    stmt.setString(3, user.getPassword());
    success = stmt.executeUpdate() > 0;
} catch (SQLException e) {
    e.printStackTrace();
}
return success;

}

User login:
public User login(String email, String password) {

User user = null;
try (Connection conn = DatabaseConnection.getConnection();
     PreparedStatement stmt = conn.prepareStatement("SELECT * FROM users WHERE email = ? AND password = ?")) {
    stmt.setString(1, email);
    stmt.setString(2, password);
    try (ResultSet rs = stmt.executeQuery()) {
        if (rs.next()) {
            user = new User();
            user.setId(rs.getInt("id"));
            user.setName(rs.getString("name"));
            user.setEmail(rs.getString("email"));
            user.setPassword(rs.getString("password"));
        }
    }
} catch (SQLException e) {
    e.printStackTrace();
}
return user;

}

The above codes are some examples and can be modified and expanded according to actual needs. In addition, you can also use Java web development frameworks such as Spring MVC or Servlet to implement more complex functions.

To summarize, developing a simple online mall system using MySQL and Java requires building a database, connecting to the database, and writing corresponding back-end code to implement various functions. This article provides some basic code examples, hoping to help readers get started quickly and implement a simple online mall system.

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