如何利用MySQL和Java开发一个简单的在线图书馆系统

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

public class DBConnection {
   private static final String url = "jdbc:mysql://localhost:3306/library_system";
   private static final String user = "root";
   private static final String passWord = "password";
   private static Connection conn = null;
   private static Statement stmt = null;
      
   public static Connection getConnection() {
      try {
         Class.forName("com.mysql.jdbc.Driver");
         conn = DriverManager.getConnection(url, user, password);
      } catch (ClassNotFoundException | SQLException e) {
         e.printStackTrace();
      }
      return conn;
   }
   
   public static ResultSet executeQuery(String query) {
      ResultSet rs = null;
      try {
         stmt = getConnection().createStatement();
         rs = stmt.executeQuery(query);
      } catch (SQLException e) {
         e.printStackTrace();
      }
      return rs;
   }
   
   public static void executeUpdate(String query) {
      try {
         stmt = getConnection().createStatement();
         stmt.executeUpdate(query);
      } catch (SQLException e) {
         e.printStackTrace();
      }
   }
}

import java.sql.ResultSet;
import java.sql.SQLException;

public class LibrarySystem {
   public static void main(String[] args) {
      borrowBook(1, 1); // 借阅书籍ID为1的书籍，读者ID为1的读者
      returnBook(1, 1); // 归还书籍ID为1的书籍，读者ID为1的读者
   }
   
   public static void borrowBook(int bookId, int readerId) {
      // 更新借阅记录表
      String borrowRecordQuery = "INSERT INTO borrow_records (book_id, reader_id, borrow_date) " +
                                 "VALUES (" + bookId + ", " + readerId + ", NOW())";
      DBConnection.executeUpdate(borrowRecordQuery);
      
      // 更新书籍表的借阅状态
      String updateBookStatusQuery = "UPDATE books SET status = '借出' WHERE book_id = " + bookId;
      DBConnection.executeUpdate(updateBookStatusQuery);
      
      System.out.println("书籍ID " + bookId + " 成功借阅给读者ID " + readerId);
   }
   
   public static void returnBook(int bookId, int readerId) {
      // 更新借阅记录表的归还日期
      String returnDateQuery = "UPDATE borrow_records SET return_date = NOW() " +
                               "WHERE book_id = " + bookId + " AND reader_id = " + readerId;
      DBConnection.executeUpdate(returnDateQuery);
      
      // 更新书籍表的借阅状态
      String updateBookStatusQuery = "UPDATE books SET status = '可借' WHERE book_id = " + bookId;
      DBConnection.executeUpdate(updateBookStatusQuery);
      
      System.out.println("书籍ID " + bookId + " 已成功归还");
   }
}