定义两个类 Book, BookDAO, 其中Book类用于封装一个书籍对象，BookDAO中实现对于文本文件Book.txt的增加、修改、删除和查询方法（至少4种查询方法）。用

首先，让我们定义`Book`类，它将包含书籍的基本信息：

public class Book {
    private String title;
    private String author;
    private int publicationYear;

    // 构造函数
    public Book(String title, String author, int publicationYear) {
        this.title = title;
        this.author = author;
        this.publicationYear = publicationYear;
    }

    // getter和setter方法
    public String getTitle() { return title; }
    public void setTitle(String title) { this.title = title; }
    public String getAuthor() { return author; }
    public void setAuthor(String author) { this.author = author; }
    public int getPublicationYear() { return publicationYear; }
    public void setPublicationYear(int publicationYear) { this.publicationYear = publicationYear; }

    @Override
    public String toString() {
        return "Book{" +
                "title='" + title + '\'' +
                ", author='" + author + '\'' +
                ", publicationYear=" + publicationYear +
                '}';
    }
}

接下来，我们创建`BookDAO`类，该类将负责对`Book.txt`文件的操作，包括增删改查功能：

import java.io.*;
import java.util.ArrayList;
import java.util.List;

public class BookDAO {
    private static final String FILE_NAME = "Book.txt";
    
    // 数据存储列表
    private static List<Book> bookList = new ArrayList<>();

    // 读取文件并填充bookList
    public static void loadBooks() {
        try (BufferedReader br = new BufferedReader(new FileReader(FILE_NAME))) {
            String line;
            while ((line = br.readLine()) != null) {
                String[] data = line.split(",");
                Book book = new Book(data[0], data[1], Integer.parseInt(data[2]));
                bookList.add(book);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // 添加书籍到文件
    public static void addBook(Book book) {
        bookList.add(book);
        saveBooks();
    }

    // 更新书籍（假设通过书名查找）
    public static void updateBook(String title, String author, int year) {
        for (int i = 0; i < bookList.size(); i++) {
            if (bookList.get(i).getTitle().equals(title)) {
                bookList.set(i, new Book(title, author, year));
                break;
            }
        }
        saveBooks();
    }

    // 删除书籍（同样通过书名查找）
    public static void deleteBook(String title) {
        bookList.removeIf(book -> book.getTitle().equals(title));
        saveBooks();
    }

    // 查询方法
    public static Book findBookByTitle(String title) {
        return bookList.stream()
                .filter(book -> book.getTitle().equals(title))
                .findFirst()
                .orElse(null);
    }

    public static List<Book> getAllBooks() {
        return bookList;
    }

    // 保存数据到文件
    private static void saveBooks() {
        try (PrintWriter pw = new PrintWriter(new FileWriter(FILE_NAME, true))) {
            for (Book book : bookList) {
                pw.println(book.getTitle() + "," + book.getAuthor() + "," + book.getPublicationYear());
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

在这个例子中，`loadBooks()`方法用于初始化文件内容，而其他方法如`addBook()`、`updateBook()`、`deleteBook()`以及`findBookByTitle()`分别实现了增加、修改、删除和查询操作。请注意，这个设计假定文件中的每一行代表一本书的信息，并且使用逗号分隔标题、作者和年份。