C#图书馆管理系统boklista搜索及Main方法位置问题咨询

问题1：如何在图书列表（boklista）中按指定关键词搜索 #

你当前写的SearchBook()方法存在逻辑偏差：方法中匹配的是bok.Text()返回的馆藏位置提示文本（比如Found in section B），而非用户实际会搜索的书名、作者、图书类型字段，会导致用户输入书名/作者时完全搜不到结果。
正确的实现逻辑如下：

• 保留大小写不敏感匹配的思路，将搜索关键词和待匹配字段统一转为小写后比对，避免大小写导致匹配失败
• 匹配字段覆盖图书核心属性：书名BookNamn、作者Author、图书类型BookType
• 匹配到结果后不要直接终止遍历，要输出匹配到的完整图书信息，方便用户查看
• 增加空值判断，避免字段为空时触发异常

修正后的SearchBook()方法参考：

public static void SearchBook()
{
    string searchKeyword;
    List<Book> matchedBooks = new List<Book>();

    // 校验搜索关键词非空
    do
    {
        Console.Write("\n\n\t\t请输入搜索关键词：");
        searchKeyword = Console.ReadLine()?.Trim();
        if (string.IsNullOrEmpty(searchKeyword))
        {
            Console.WriteLine("\n\n\t\t搜索关键词不能为空，请重新输入！\n");
        }
    } while (string.IsNullOrEmpty(searchKeyword));

    string lowerKeyword = searchKeyword.ToLower();
    // 遍历匹配所有符合条件的图书
    foreach (var book in bookList)
    {
        bool isMatch = 
            (book.BookNamn?.ToLower().Contains(lowerKeyword) ?? false) ||
            (book.Author?.ToLower().Contains(lowerKeyword) ?? false) ||
            (book.BookType?.ToLower().Contains(lowerKeyword) ?? false);
        
        if (isMatch)
        {
            matchedBooks.Add(book);
        }
    }

    // 输出结果
    if (matchedBooks.Count == 0)
    {
        Console.WriteLine($"\n\n\t\t未找到和关键词「{searchKeyword}」匹配的图书。");
        return;
    }

    Console.WriteLine($"\n\n\t\t共找到{matchedBooks.Count}本匹配的图书：");
    foreach (var book in matchedBooks)
    {
        Console.WriteLine(book.ToString());
        Console.WriteLine(book.Text() + "\n");
    }
}

问题2：Main方法放在静态Librarian类中是否不合理，是否需要拆分 #

• 从C#语法规则来说，静态类中放置Main方法作为程序入口是完全合法的，对于小型演示项目来说这种写法没有问题，可以正常运行。
• 但从你要求实现封装、多态的设计目标，以及后续代码可维护性的角度来说，建议拆分，原因如下：
  • 不符合单一职责原则：Librarian（图书管理员）类的核心职责是封装图书列表、处理图书新增/查询/遍历等业务逻辑；而Main方法的作用是程序启动、渲染交互菜单、处理用户输入的流程控制，二者职责边界完全不同，混写在一起后续功能迭代（比如新增借书/还书、用户权限管理功能）时，类的代码会快速膨胀变得难以维护。
  • 不利于业务逻辑复用：如果后续你需要给这个系统加图形界面、或者提供API接口，把入口逻辑和业务逻辑拆分后，可以直接复用Librarian类里的所有图书操作方法，不需要重复写业务代码。
• 拆分方式非常简单，不会破坏你现有的封装设计：
  1. 新建一个Program类，把Main方法完整挪到这个类里作为程序唯一入口
  2. Librarian类保留为封装图书业务的类，bookList依旧保持private访问权限，对外只暴露需要的操作方法，完全符合封装要求。

附：原始提交代码 #

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace bibliotekarie
{
    public class Book
    {
        public string BookNamn;
        public string Author;
        public string BookType;


        public Book(string _BookNamn, String _Author, string _BookType)
        {
            BookNamn = _BookNamn;
            Author = _Author;
            BookType = _BookType;
        }

        public override string ToString()
        {
            return "\n\t\t" + BookNamn + " (" + BookType + ")"
            + "\n\t\tby " + Author;
        }

        public virtual string Text()
        {
            return "\t\tFound in section A.";
        }
    }

    public class Novel : Book
    {
        public Novel(string _BookNamn, String _Author, string _BookType) : base(_BookNamn, _Author, _BookType)
        {
            this.BookType = "Novel";
        }

        public override string Text()
        {
            return "\t\tFound in section B.";
        }
    }

    public class ShortStory : Book
    {
        public ShortStory(string _BookNamn, String _Author, string _BookType) : base(_BookNamn, _Author, _BookType)
        {
            this.BookType = "ShortStory";
        }

        public override string Text()
        {
            return "\t\tFound in section C.";
        }
    }

    public class Journal : Book
    {
        public Journal(string _BookNamn, String _Author, string _BookType) : base(_BookNamn, _Author, _BookType)
        {
            this.BookType = "Journal";
        }

        public override string Text()
        {
            return "\t\tFound in section D.";
        }
    }

    static class Librarian
    {

        private static List<Book> bookList = new List<Book>();

        public static void GetBookList()
        {
            foreach (Book item in bookList)
            {
                Console.WriteLine(item.ToString() + "\n");
                Console.WriteLine(item.Text() + "\n");
            }
        }
        public static void CreateBook()
        {
            string name = "";
            string author = "";

            while (name.Length == 0)
            {
                Console.Write("\n\n\t\tStart by entering the name of the book. Please enter the name: ");
                name = Console.ReadLine();
            }

            while (author.Length == 0)
            {
                Console.Write("\n\n\t\tWho is the author of the book?: ");
                author = Console.ReadLine();
            }

            Console.Write("\n\n\t\tPlease specify the book type: [1] Novel, [2] Journal, or [3] Short story?: ");
            int nyVal;
            int.TryParse(Console.ReadLine(), out nyVal);

            switch (nyVal)
            {
                case 1:
                    {
                        Book newBok = new Novel(name, author, "(Novel)");
                        bookList.Add(newBok);
                        Console.ForegroundColor = ConsoleColor.Yellow;
                        Console.WriteLine("\n\n\t\tSaved!");
                        Console.ResetColor();
                        break;
                    }
                case 2:
                    {
                        Book newBok = new Journal(name, author, "(Journal)");
                        bookList.Add(newBok);
                        Console.ForegroundColor = ConsoleColor.Yellow;
                        Console.WriteLine("\n\n\t\tSaved!");
                        Console.ResetColor();
                        break;
                    }
                case 3:
                    {
                        Book newBok = new ShortStory(name, author, "(Short story)");
                        bookList.Add(newBok);
                        Console.ForegroundColor = ConsoleColor.Yellow;
                        Console.WriteLine("\n\n\t\tSaved!");
                        Console.ResetColor();
                        break;
                    }
                default:
                    {
                        Console.ForegroundColor = ConsoleColor.Red;
                        Console.WriteLine("\n\n\t\tNågonting gick fel. Det gick inte att spara. Testa igen.");
                        Console.ResetColor();

                        break;
                    }
            }


        }
        public static void SearchBook()
        {
            string searchItems;
            bool found = false;

            do
            {
                Console.Write("\n\n\t\tSearch the library: ");
                searchItems = Console.ReadLine();
                if (searchItems == "")
                {
                    Console.WriteLine("\n\n\t\tThe search field cannot be empty. Try again!\n");
                }
            } while (searchItems == "");


            // this is what I added
            // for each bok in list
            foreach (var bok in bookList)
            {

                // if bok text matches searchItems
                //if(bok.Text() == searchItems) {   // commented out exact match, to get similar matches using Contains
                if (bok.Text().ToLower().Contains(searchItems.ToLower()))
                {
                    found = true;
                    break;
                }
            }

            if (found)
            {
                Console.WriteLine("\n\n\t\t" + searchItems + " was found.");
            }
            else
            {
                Console.WriteLine("\n\n\t\t" + searchItems + " was not found.");
            }
        }

        static void Main(string[] args)
        {
            bookList.Add(new Book("Book1", "Author1", "Book"));
            bookList.Add(new Novel("Book2", "Author2", "Novel"));
            bookList.Add(new Journal("Book3", "Author3", "Journal"));
            bookList.Add(new ShortStory("Book4", "Author4", "Short Story"));
            bool isRunning = true;
            while (isRunning)
            {


                Console.Write("\n\n\t\tWelcome to the library!\n");
                Console.WriteLine("\n\n\t\t[1] Register a new book");
                Console.WriteLine("\n\n\t\t[2] View a list of the books");
                Console.WriteLine("\n\n\t\t[3] Search through the library database");
                Console.WriteLine("\n\n\t\t[4] End program");
                Console.Write("\n\n\t\tChoose: ");

                int Choice;
                Int32.TryParse(Console.ReadLine(), out Choice);


                switch (Choice)
                {
                    case 1:
                        CreateBook();

                        break;
                    case 2:

                        GetBookList();
                        Console.ReadLine();

                        break;
                    case 3:

                        SearchBook();

                        break;
                    case 4:

                        Console.ForegroundColor = ConsoleColor.Red;
                        Console.WriteLine("\n\n\t\tThis program will now close.");
                        Thread.Sleep(1500);
                        Console.ResetColor();
                        isRunning = false;
                        break;

                    default:
                        Console.WriteLine("\n\n\t\tAn error occurred, but you can try again.");
                        break;
                }
            }

        }
    }
}

内容的提问来源于stack exchange，提问作者uuresearcher