帮我用java写一个图书馆管理系统 要求 ： 1）具备对书籍信息的维护功能（添加、删除、修改） 2）具备对借阅人信息的维护功能（添加、删除、修改） 3）具备对借阅管理的维护功能（添加、删除、修改） 4）具备对图书的查询功能（按书号、书名、或借书时间、借书人等查询 ） 5）具备对相关信息的统计功能（借阅人次，个人借阅统计，最受欢迎的书，借阅最少的书等）

好的，这是一个比较复杂的项目，需要一些时间和精力来完成。我可以给你一些实现思路和代码示例，希望能对你有所帮助。

首先，我们需要定义一些数据结构来存储图书馆的信息，比如书籍、借阅人、借阅记录等。这里我定义了三个类：Book、Borrower、BorrowRecord。

public class Book {
    private String bookId; // 书籍编号
    private String bookName; // 书籍名称
    private String author; // 作者
    private String publisher; // 出版社
    private int totalNum; // 总数量
    private int remainNum; // 剩余数量

    // getter and setter methods
}

public class Borrower {
    private String borrowerId; // 借阅人编号
    private String borrowerName; // 借阅人姓名
    private String phone; // 电话号码

    // getter and setter methods
}

public class BorrowRecord {
    private Book book; // 借阅的书籍
    private Borrower borrower; // 借阅人
    private Date borrowDate; // 借阅日期
    private Date returnDate; // 归还日期

    // getter and setter methods
}

接下来，我们需要实现对这些信息的维护功能。这里我定义了一个Library类，包含了一些方法来添加、删除、修改和查询图书、借阅人、借阅记录等信息。

public class Library {
    private List<Book> books; // 书籍列表
    private List<Borrower> borrowers; // 借阅人列表
    private List<BorrowRecord> borrowRecords; // 借阅记录列表

    public Library() {
        books = new ArrayList<>();
        borrowers = new ArrayList<>();
        borrowRecords = new ArrayList<>();
    }

    // 添加书籍
    public void addBook(Book book) {
        books.add(book);
    }

    // 删除书籍
    public void removeBook(Book book) {
        books.remove(book);
    }

    // 修改书籍
    public void updateBook(Book book) {
        // 找到对应的书籍，并更新信息
        for (int i = 0; i < books.size(); i++) {
            if (books.get(i).getBookId().equals(book.getBookId())) {
                books.set(i, book);
                break;
            }
        }
    }

    // 添加借阅人
    public void addBorrower(Borrower borrower) {
        borrowers.add(borrower);
    }

    // 删除借阅人
    public void removeBorrower(Borrower borrower) {
        borrowers.remove(borrower);
    }

    // 修改借阅人
    public void updateBorrower(Borrower borrower) {
        // 找到对应的借阅人，并更新信息
        for (int i = 0; i < borrowers.size(); i++) {
            if (borrowers.get(i).getBorrowerId().equals(borrower.getBorrowerId())) {
                borrowers.set(i, borrower);
                break;
            }
        }
    }

    // 添加借阅记录
    public void addBorrowRecord(BorrowRecord borrowRecord) {
        borrowRecords.add(borrowRecord);
    }

    // 删除借阅记录
    public void removeBorrowRecord(BorrowRecord borrowRecord) {
        borrowRecords.remove(borrowRecord);
    }

    // 修改借阅记录
    public void updateBorrowRecord(BorrowRecord borrowRecord) {
        // 找到对应的借阅记录，并更新信息
        for (int i = 0; i < borrowRecords.size(); i++) {
            if (borrowRecords.get(i).getBook().getBookId().equals(borrowRecord.getBook().getBookId())
                    && borrowRecords.get(i).getBorrower().getBorrowerId().equals(borrowRecord.getBorrower().getBorrowerId())) {
                borrowRecords.set(i, borrowRecord);
                break;
            }
        }
    }

    // 按书籍编号查询书籍
    public Book findBookById(String bookId) {
        for (Book book : books) {
            if (book.getBookId().equals(bookId)) {
                return book;
            }
        }
        return null;
    }

    // 按书籍名称查询书籍
    public List<Book> findBookByName(String bookName) {
        List<Book> result = new ArrayList<>();
        for (Book book : books) {
            if (book.getBookName().contains(bookName)) {
                result.add(book);
            }
        }
        return result;
    }

    // 按借阅人姓名查询借阅人
    public List<Borrower> findBorrowerByName(String borrowerName) {
        List<Borrower> result = new ArrayList<>();
        for (Borrower borrower : borrowers) {
            if (borrower.getBorrowerName().contains(borrowerName)) {
                result.add(borrower);
            }
        }
        return result;
    }

    // 按借阅时间查询借阅记录
    public List<BorrowRecord> findBorrowRecordByDate(Date borrowDate, Date returnDate) {
        List<BorrowRecord> result = new ArrayList<>();
        for (BorrowRecord borrowRecord : borrowRecords) {
            if (borrowRecord.getBorrowDate().compareTo(borrowDate) >= 0 && borrowRecord.getReturnDate().compareTo(returnDate) <= 0) {
                result.add(borrowRecord);
            }
        }
        return result;
    }

    // 按借阅人查询借阅记录
    public List<BorrowRecord> findBorrowRecordByBorrower(Borrower borrower) {
        List<BorrowRecord> result = new ArrayList<>();
        for (BorrowRecord borrowRecord : borrowRecords) {
            if (borrowRecord.getBorrower().getBorrowerId().equals(borrower.getBorrowerId())) {
                result.add(borrowRecord);
            }
        }
        return result;
    }

    // 统计借阅人次
    public int countBorrowTimes() {
        return borrowRecords.size();
    }

    // 统计个人借阅次数
    public int countBorrowTimesByBorrower(Borrower borrower) {
        int count = 0;
        for (BorrowRecord borrowRecord : borrowRecords) {
            if (borrowRecord.getBorrower().getBorrowerId().equals(borrower.getBorrowerId())) {
                count++;
            }
        }
        return count;
    }

    // 统计最受欢迎的书
    public Book getMostPopularBook() {
        Book result = null;
        int maxBorrowTimes = 0;
        for (Book book : books) {
            int borrowTimes = 0;
            for (BorrowRecord borrowRecord : borrowRecords) {
                if (borrowRecord.getBook().getBookId().equals(book.getBookId())) {
                    borrowTimes++;
                }
            }
            if (borrowTimes > maxBorrowTimes) {
                maxBorrowTimes = borrowTimes;
                result = book;
            }
        }
        return result;
    }

    // 统计借阅最少的书
    public Book getLeastBorrowedBook() {
        Book result = null;
        int minBorrowTimes = Integer.MAX_VALUE;
        for (Book book : books) {
            int borrowTimes = 0;
            for (BorrowRecord borrowRecord : borrowRecords) {
                if (borrowRecord.getBook().getBookId().equals(book.getBookId())) {
                    borrowTimes++;
                }
            }
            if (borrowTimes < minBorrowTimes) {
                minBorrowTimes = borrowTimes;
                result = book;
            }
        }
        return result;
    }
}

最后，我们可以写一个Demo来演示这个图书馆管理系统的功能。

public class LibraryDemo {
    public static void main(String[] args) {
        // 创建图书馆对象
        Library library = new Library();

        // 添加书籍
        Book book1 = new Book();
        book1.setBookId("001");
        book1.setBookName("Java编程思想");
        book1.setAuthor("Bruce Eckel");
        book1.setPublisher("机械工业出版社");
        book1.setTotalNum(5);
        book1.setRemainNum(5);
        library.addBook(book1);

        Book book2 = new Book();
        book2.setBookId("002");
        book2.setBookName("Effective Java");
        book2.setAuthor("Joshua Bloch");
        book2.setPublisher("机械工业出版社");
        book2.setTotalNum(3);
        book2.setRemainNum(3);
        library.addBook(book2);

        // 添加借阅人
        Borrower borrower1 = new Borrower();
        borrower1.setBorrowerId("001");
        borrower1.setBorrowerName("张三");
        borrower1.setPhone("13888888888");
        library.addBorrower(borrower1);

        Borrower borrower2 = new Borrower();
        borrower2.setBorrowerId("002");
        borrower2.setBorrowerName("李四");
        borrower2.setPhone("13999999999");
        library.addBorrower(borrower2);

        // 添加借阅记录
        BorrowRecord borrowRecord1 = new BorrowRecord();
        borrowRecord1.setBook(book1);
        borrowRecord1.setBorrower(borrower1);
        borrowRecord1.setBorrowDate(new Date());
        borrowRecord1.setReturnDate(null);
        library.addBorrowRecord(borrowRecord1);

        BorrowRecord borrowRecord2 = new BorrowRecord();
        borrowRecord2.setBook(book1);
        borrowRecord2.setBorrower(borrower2);
        borrowRecord2.setBorrowDate(new Date());
        borrowRecord2.setReturnDate(null);
        library.addBorrowRecord(borrowRecord2);

        // 查询书籍
        Book book = library.findBookById("001");
        System.out.println(book.getBookName());

        List<Book> books = library.findBookByName("Java");
        for (Book b : books) {
            System.out.println(b.getBookName());
        }

        // 查询借阅人
        List<Borrower> borrowers = library.findBorrowerByName("张");
        for (Borrower borrower : borrowers) {
            System.out.println(borrower.getBorrowerName());
        }

        // 查询借阅记录
        List<BorrowRecord> borrowRecords = library.findBorrowRecordByDate(new Date(), new Date());
        for (BorrowRecord borrowRecord : borrowRecords) {
            System.out.println(borrowRecord.getBorrower().getBorrowerName() + "借阅了" + borrowRecord.getBook().getBookName());
        }

        // 统计借阅人次
        System.out.println(library.countBorrowTimes());

        // 统计个人借阅次数
        System.out.println(library.countBorrowTimesByBorrower(borrower1));

        // 统计最受欢迎的书
        System.out.println(library.getMostPopularBook().getBookName());

        // 统计借阅最少的书
        System.out.println(library.getLeastBorrowedBook().getBookName());
    }
}

这个Demo只是一个简单的例子，实际上还有很多细节需要考虑，比如图书的借阅和归还、借阅人的罚款和信用等等。希望这个示例能够帮助你开发出一个完整的图书馆管理系统。