JAVA简单的图书管理系统

1.类

图书类的设计主要是图书的一些基本属性：

1.1 图书类

import java.util.Date;

/**

* 图书

* @author 李海明

*

*/

public class Book {

private int id; //图书编号

private String isbn; //isbn编号

private String name; //书名

private double price; //价格

private String author; //作者

private String publisher; //出版社

private Date pubDate; // 出版日期

private boolean lended; //借阅状态（是否借出）

private int counter; // 被借阅总次数

private String type; // 图书类型

/**

* 下面属性的get和set方法

*/

public String getType() {

return type;

}

public void setType(String type) {
this.type = type;
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getIsbn() {
return isbn;
}

public void setIsbn(String isbn) {
this.isbn = isbn;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public double getPrice() {
return price;
}

public void setPrice(double price) {
this.price = price;
}

public String getAuthor() {
return author;
}

public void setAuthor(String author) {
this.author = author;
}

public String getPublisher() {
return publisher;
}

public void setPublisher(String publisher) {
this.publisher = publisher;
}

public Date getPubDate() {
return pubDate;
}

public void setPubDate(Date pubDate) {
this.pubDate = pubDate;
}

public boolean isLended() {
return lended;
}

public void setLended(boolean lended) {
this.lended = lended;
}

public int getCounter() {
return counter;
}

public void setCounter(int counter) {
this.counter = counter;
}

}

1.2 读者类

import java.util.Date;

/**

* 读者

* @author 李海明

*

*/

public class Reader {

private int id; //编号

private String name;//名字

private boolean gender;//性别

private String tel;//电话

private Date registerDate;//注册时间

private boolean available;//是否注销

private boolean isVip=false;//是否vip

private int maxLendeddate;//最大借书天数

private int lendednum;//当前借书未还数量

/**

* 读者的get和set方法

*/

public int getLendednum() {

return lendednum;

}

public void setLendednum(int lendednum) {
this.lendednum = lendednum;
}

public boolean isVip() {
return isVip;
}

public void setVip(boolean isVip) {
this.isVip = isVip;
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public boolean isGender() {
return gender;
}

public void setGender(boolean gender) {
this.gender = gender;
}

public String getTel() {
return tel;
}

public void setTel(String tel) {
this.tel = tel;
}

public Date getRegisterDate() {
return registerDate;
}

public void setRegisterDate(Date registerDate) {
this.registerDate = registerDate;
}

public boolean isAvailable() {
return available;
}

public void setAvailable(boolean available) {
this.available = available;
}

}

2.工具类

2.1 导入jdbc-jar包

与数据库有关的操作放在这个类中，首先需要导入jdbc的jar包，步骤：1.下载jdbc-jar包 2.在Eclipse上右击项目，build path->add external archive->选择jar包就ok了

2.2 JdbcUtil工具类

import java.io.IOException;

import java.io.InputStream;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.Properties;

/** <
4000
br>
* JDBC操作工具类

* @author 李海明

*

*/

public class JdbcUtil {

private static Properties props = new Properties();

static {
try (InputStream inputStream = JdbcUtil.class.getClassLoader()
.getResourceAsStream("jdbc.properties")) {
props.load(inputStream);
Class.forName(props.getProperty("drv"));
} catch (IOException | ClassNotFoundException e) {
e.printStackTrace();
}
}

private JdbcUtil() {
throw new AssertionError();
}

/**
* 获得数据库连接
* @return Connection对象
*/
public static Connection getConnection() {
try {
return DriverManager.getConnection(
props.getProperty("url"), props.getProperty("uid"), props.getProperty("pwd"));
} catch (SQLException e) {
throw new RuntimeException(e);
}
}

/**
* 关闭数据库连接
* @param connection 连接对象
*/
public static void closeConnection(Connection connection) {
try {
if (connection != null && !connection.isClosed()) {
connection.close();
}
} catch (SQLException e) {
throw new RuntimeException(e);
}
}

/**
* 开启事务
* @param connection 连接对象
*/
public static void beginTx(Connection connection) {
try {
connection.setAutoCommit(false);
} catch (SQLException e) {
throw new RuntimeException(e);
}
}

/**
* 提交事务
* @param connection 连接对象
*/
public static void commitTx(Connection connection) {
try {
connection.commit();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}

/**
* 回滚事务
*/
public static void rollbackTx(Connection connection) {
try {
connection.rollback();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}

/**
* 执行增删改操作
* @param con 连接对象
* @param sql SQL语句
* @param params 替换占位符的参数
* @return 受影响的行数
* @throws SQLException
*/
public static int executeUpdate(Connection con, String sql, Object... params) throws SQLException {
try (PreparedStatement stmt = con.prepareStatement(sql)) {
for (int i = 0; i < params.length; ++i) {
stmt.setObject(i + 1, params[i]);
}
return stmt.executeUpdate();
}
}
public static ResultSet executeSelect(Connection con, String sql, Object... params) throws SQLException {
try (PreparedStatement stmt = con.prepareStatement(sql)) {
for (int i = 0; i < params.length; ++i) {
stmt.setObject(i + 1, params[i]);
}
return stmt.executeQuery();
}
}

}

3. 管理类

将一些操作书本的方法封装在**bookManager**类中，有利于管理和修改。

3.1 bookmanager类

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.Date;

import java.util.Collections;

import java.util.List;

import javax.swing.text.StyledEditorKit.ForegroundAction;

import com.mysql.jdbc.Statement;

/**

* 图书管理器

*

* @author 李海明

*

*/

public class BookManager {

/**
* 添加新图书
* @param book 图书
* @return 添加成功返回true 否则返回false
*/
public boolean addNewBook(Book book) {
try (Connection connection = JdbcUtil.getConnection()) {
return JdbcUtil.executeUpdate(connection,
"insert into tb_book (bookid, isbn, bname, price, author, publisher, pubdate) values (?,?,?,?,?,?,?)",
book.getId(), book.getIsbn(), book.getName(), book.getPrice(), book.getAuthor(),
book.getPublisher(), book.getPubDate()) == 1;
} catch (SQLException e) {
e.printStackTrace();
}
return false;
}

/**
* 根据编号移除图书(不可借阅)
* @param id
* @return 移除成功返回true 否则返回false
*/
public boolean removeBookById(int id) {
try (Connection connection = JdbcUtil.getConnection()) {
return JdbcUtil.executeUpdate(connection, "update tb_book set lended=1 where bookid=? and lended=0",
id) == 1;
} catch (SQLException e) {
e.printStackTrace();
}
return false;
}

/**
* 借出图书
* @param bookId 图书编号
* @param readerId 读者编号
* @return 借出成功返回true 否则返回false
*/
@SuppressWarnings("resource")
public boolean lendOut(int bookId, int readerId) {
Connection connection = JdbcUtil.getConnection();
try {
PreparedStatement stmt = connection.prepareStatement(
"select available from tb_reader where  lendednum<maxlendednum and readerid=?");
stmt.setInt(1, readerId);
ResultSet rs = stmt.executeQuery();
// 事务(transaction) - 不可分割的一组原子性操作
// 事务的ACID特性
//  - Atomicity(原子性) - 不可分割要么全做要么全不做
// - Consistency(一致性) - 事务前后数据状态保持一致
// - Isolation(隔离性) - 事务不能看到彼此的中间状态
// - Duration(持久性) - 事务完成后数据要持久化
if (rs.next() && rs.getBoolean(1)){
JdbcUtil.beginTx(connection);

if (JdbcUtil.executeUpdate(connection,
"update tb_book set lended=1, counter=counter+1 where lended=0 and bookid=? ",
bookId) == 1) {
int affectedRows = JdbcUtil.executeUpdate(connection,
"insert into tb_record (bid, rid, lenddate) values (?,?,?)",
bookId, readerId, new Date(System.currentTimeMillis()));
JdbcUtil.executeUpdate(connection, "update tb_reader set lendednum=lendednum+1 where readerid=?",readerId);
// 如果没有发生异常就提交事务
JdbcUtil.commitTx(connection);
return affectedRows == 1;
}
}else{
System.out.println("超出可借最大数量！如要继续借书，请注册会员！");
}
} catch (SQLException e) {
e.printStackTrace();
// 如果发生了异常就让事务回滚
JdbcUtil.rollbackTx(connection);
} finally {
JdbcUtil.closeConnection(connection);
}
return false;
}

/**
* 归还图书
* @param bookId 图书编号
* @param readerId 读者编号
* @return 如果超期则返回罚款金额 否则返回0 操作失败返回-1
*/
@SuppressWarnings("resource")
public double returnBack(int bookId, int readerId) {
double pulishment = 0;
Connection connection = JdbcUtil.getConnection();
try  {
JdbcUtil.beginTx(connection);
if (JdbcUtil.executeUpdate(connection,
"update tb_book set lended=0 where lended=1 and bookid=?",
bookId) == 1) {
PreparedStatement stmt = connection.prepareStatement(
"select recordid, lenddate from tb_record where lenddate=("
+ "select max(lenddate) from tb_record where bid=? and rid=?) "
+ "and bid=? and rid=? ");
stmt.setInt(1, bookId);
stmt.setInt(2, readerId);
stmt.setInt(3, bookId);
stmt.setInt(4, readerId);
ResultSet rs = stmt.executeQuery();
PreparedStatement statement=connection.prepareStatement("select"
+ " maxlendeddate from tb_reader where readerid=?");//获取读者最大天数和当前借书数量
statement .setInt(1, readerId);
ResultSet rSet=statement .executeQuery();
int maxlendeddate = 0;
if(rSet.next()){
maxlendeddate=rSet.getInt("maxlendeddate");
}
if (rs.next()) {
int recordId = rs.getInt("recordid");
Date lendDate = rs.getDate("lenddate");
Date backDate = new Date();

double days = Math.ceil((backDate.getTime() - lendDate.getTime()) / 86400000.0);
pulishment = days > maxlendeddate ?
Math.round((days -maxlendeddate) * 0.2 * 100) / 100.0 : 0;
JdbcUtil.executeUpdate(connection,
"update tb_record set backdate=?, pulishment=? where recordid=?",
backDate, pulishment, recordId);
JdbcUtil.executeUpdate(connection, "update tb_reader set lendednum=lendednum-1");//还书成功后，当前借书书减1
}

}
JdbcUtil.commitTx(connection);
return pulishment;
} catch (SQLException e) {
e.printStackTrace();
JdbcUtil.rollbackTx(connection);
} finally {
JdbcUtil.closeConnection(connection);
}
return -1;
}

/**
* 根据图书编号查找图书
* @param id 图书编号
* @return 图书对象或null
*/
@SuppressWarnings("resource")
public Book searchBookById(int id) {
try (Connection connection = JdbcUtil.getConnection()) {
PreparedStatement stmt = connection.prepareStatement(
"select bookid, isbn, bname, price, author, publisher, pubdate, lended, counter from tb_book where bookid=?");
stmt.setInt(1, id);
ResultSet rs = stmt.executeQuery();
if (rs.next()) {
return handleResultSet(rs);
}
} catch (SQLException e) {
e.printStackTrace();
}
return null;
}

/**
* 根据ISBN号查找图书
* @param isbn
* @return 保存查询结果的列表容器
*/
public List<Book> searchBookByIsbn(String isbn) {
List<Book> bookList = new ArrayList<>();
try (Connection connection = JdbcUtil.getConnection()) {
@SuppressWarnings("resource")
PreparedStatement stmt = connection.prepareStatement(
"select bookid, isbn, bname, price, author, publisher, pubdate, lended, counter from tb_book where isbn=?");
stmt.setString(1, isbn);
@SuppressWarnings("resource")
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
Book book = handleResultSet(rs);
bookList.add(book);
}
} catch (SQLException e) {
e.printStackTrace();
}
return bookList.size() > 0 ? bookList : Collections.emptyList();
}
/**
* 根据分类查找图书
*/
public  List <Book> ground(String type,Object...params){
List<Book> sametype=new ArrayList<Book>();
try(Connection connection =JdbcUtil.getConnection()){
/*PreparedStatement statement=connection.prepareStatement(
"select bookid, isbn,"
+ " bname, price, author, publisher, pubdate, lended,"
+ " counter from tb_book where type=?)");
statement.setString(1,type);
ResultSet rSet=statement.executeQuery();*/
ResultSet rSet=JdbcUtil.executeSelect(connection,"select bookid, isbn,"
+ " bname, price, author, publisher, pubdate, lended,"
+ " counter from tb_book where type=? ",type);
while(rSet.next()){
Book book=handleResultSet(rSet);
sametype.add(book);

}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return sametype.size() > 0 ? sametype : Collections.emptyList();

}

/**
*
* 根据书名查找图书
* @param name 书名(支持模糊查找)
* @return 保存查询结果的列表容器
*/
public List<Book> searchBookByName(String name) {
List<Book> bookList = new ArrayList<>();
try (Connection connection = JdbcUtil.getConnection()) {
@SuppressWarnings("resource")
PreparedStatement stmt = connection.prepareStatement(
"select bookid, isbn, bname, price, author, publisher, pubdate, lended, counter from tb_book where bname like ?");
stmt.setString(1, "%" + name + "%");
@SuppressWarnings("resource")
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
Book book = handleResultSet(rs);
bookList.add(book);
}
} catch (SQLException e) {
e.printStackTrace();
}
return bookList.size() > 0 ? bookList : Collections.emptyList();
}

/**
* 根据作者查找图书
* @param author  作者
* @return 保存查询结果的列表容器
*/
public List<Book> searchBookByAuthor(String author) {
List<Book> bookList = new ArrayList<>();
try (Connection connection = JdbcUtil.getConnection()) {
@SuppressWarnings("resource")
PreparedStatement stmt = connection.prepareStatement(
"select bookid, isbn, bname, price, author, publisher, pubdate, lended, counter from tb_book where author like ?");
stmt.setString(1, "%" + author + "%");
@SuppressWarnings("resource")
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
Book book = handleResultSet(rs);
bookList.add(book);
}
} catch (SQLException e) {
e.printStackTrace();
}
return bookList.size() > 0 ? bookList : Collections.emptyList();
}

/**
* 查询借阅排行榜前10名
* @return 保存查询结果的列表容器
*/
public List<Book> searchTop10Books() {
List<Book> bookList = new ArrayList<>();
try (Connection connection = JdbcUtil.getConnection()) {
@SuppressWarnings("resource")
PreparedStatement stmt = connection.prepareStatement(
"select bookid, isbn, bname, price, author, publisher,"
+ " pubdate, lended, sum(counter) as counter"
+ " from tb_book group by isbn order by counter desc limit 10");
@SuppressWarnings("resource")
ResultSet rs = stmt.executeQuery();
while (rs.next()) {
Book book = handleResultSet(rs);
bookList.add(book);
}
} catch (SQLException e) {
e.printStackTrace();
}
return bookList.size() > 0 ? bookList : Collections.emptyList();
}

// 处理结果集
private Book handleResultSet(ResultSet rs) throws SQLException {
Book book = new Book();
book.setId(rs.getInt("bookid"));
book.setIsbn(rs.getString("isbn"));
book.setName(rs.getString("bname"));
book.setPrice(rs.getDouble("price"));
book.setAuthor(rs.getString("author"));
book.setPublisher(rs.getString("publisher"));
book.setPubDate(rs.getDate("pubdate"));
book.setLended(rs.getBoolean("lended"));
book.setCounter(rs.getInt("counter"));
return book;
}

}

3.2 readerManager类

package com.qfedu;

import java.sql.Connection;

import java.sql.SQLException;

import java.util.Date;

/**

* @author 李海明

* 为了找个漂亮

又会调bug

的女朋友

请努力学习！

*/

public class ReaderManager {

/**
* 新增一个读者
* @param reader 读者
* @return 新增成功返回true 否则返回false
*/
public boolean createNewReader(Reader reader) {
try (Connection connection = JdbcUtil.getConnection()) {
return JdbcUtil.executeUpdate(connection,
"insert into tb_reader (readerid, rname, gender, tel, regdate) values (?,?,?,?,?)",
reader.getId(), reader.getName(), reader.isGender(), reader.getTel(),
new Date()) == 1;
} catch (SQLException e) {
e.printStackTrace();
}
return false;
}

/**
* 注销一个读者
* @param id 读者编号
* @return 注销成功返回true 否则返回false
*/
public boolean cancelReaderById(int id) {
try (Connection connection = JdbcUtil.getConnection()) {
return JdbcUtil.executeUpdate(connection,
"update tb_reader set available=0 where readerid=? and lendednum=0", id) == 1;
} catch (SQLException e) {
e.printStackTrace();
}
return false;
}

/**
* 编辑读者电话
* @param reader 读者
* @return 编辑成功返回true 否则返回false
*/

public boolean editReaderInfo(Reade
a1b3
r reader) {
try (Connection connection = JdbcUtil.getConnection()) {

return JdbcUtil.executeUpdate(connection,
"update tb_reader set tel=? where readerid=? ",
reader.getTel(), reader.getId()) == 1;
} catch (SQLException e) {
e.printStackTrace();
}
return false;
}

/**
* 注册会员
*/
public void upToVip(int readerid){
try(Connection connection =JdbcUtil.getConnection()){
if(JdbcUtil .executeUpdate(connection, "update "
+ "tb_reader set isVip=1,maxlendeddate=60,maxlendednum=10 where readerid=?",readerid)==1){
System.out.println("注册成功！！！");
}else{
System.out.println("注册失败！");
}

} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("注册失败！");
}
}

}

管理系统类（控制台显示）

BookMIS

package com.qfedu;

import java.util.Date;

import java.util.List;

import java.util.Scanner;

public class BookMIS {

private static BookManager bookManager = new BookManager();

private static ReaderManager readerManager= new ReaderManager();

private static Scanner scanner = new Scanner(System.in);

public static void main(String[] args) {
boolean isRunning = true;
System.out.println("===欢迎使用ABC图书管理系统===");
while (isRunning) {
int choice;
System.out.println("1. 管理读者");
System.out.println("2. 管理图书");
System.out.println("3. 退出系统");
do {
System.out.print("请选择: ");
choice = scanner.nextInt();
} while (choice < 1 || choice > 3);
switch (choice) {
case 1:
showReaderSubMenu();
break;
case 2:
showBookSubMenu();
break;
case 3:
System.out.println("感谢使用本系统, 欢迎下次再来");
isRunning = false;
break;
}
}
scanner.close();
}

private static void showReaderSubMenu() {
System.out.println("======读者管理子系统======");
boolean flag = true;
int choice;
while (flag) {
System.out.println("1. 新增读者");
System.out.println("2. 注销读者");
System.out.println("3. 修改信息");
System.out.println("4. 返回主菜单");
System.out.println("5. 注册会员");
do {
System.out.print("请选择: ");
choice = scanner.nextInt();
} while (choice < 1 || choice > 5);
switch (choice) {
case 1:
addReader();
break;
case 2:
cancelReader();
break;
case 3:
editReader();
break;
case 4:
flag = false;
break;
case 5:
addvip();
break;
}
}
}
private static void addvip(){
System.out.println("请输入要注册会员的读者编号");
int id=scanner.nextInt();
readerManager.upToVip(id);
}

private static void addReader() {
System.out.print("编号: ");
int id = scanner.nextInt();
System.out.print("姓名: ");
String name = scanner.next();
System.out.print("性别(1. 男, 0. 女): ");
int gender = scanner.nextInt();
System.out.print("电话: ");
String tel = scanner.next();
Reader reader = new Reader();
reader.setId(id);
reader.setName(name);
reader.setGender(gender == 1);
reader.setTel(tel);
if (readerManager.createNewReader(reader)) {
System.out.println("添加读者成功!");
} else {
System.out.println("操作失败!!!");
}
}

private static void cancelReader() {
System.out.print("编号: ");
int id = scanner.nextInt();
if (readerManager.cancelReaderById(id)) {
System.out.println("注销成功!");
} else {
System.out.println("注销失败!");
}
}

private static void editReader() {
System.out.print("编号: ");
int id = scanner.nextInt();
System.out.print("电话: ");
String tel = scanner.next();
Reader reader = new Reader();
reader.setId(id);
reader.setTel(tel);
if (readerManager.editReaderInfo(reader)) {
System.out.println("更新读者电话成功!");
} else {
System.out.println("更新读者电话失败!");
}
}

private static void showBookSubMenu() {
System.out.println("======图书管理子系统======");
boolean flag = true;
int choice;
while (flag) {
System.out.println("1. 新增图书");
System.out.println("2. 下架图书");
System.out.println("3. 借出图书");
System.out.println("4. 归还图书");
System.out.println("5. 按编号查找图书");
System.out.println("6. 按书名查找图书");
System.out.println("7. Top10排行榜");
System.out.println("8. 返回主菜单");
System.out.println("9. 按类型查找图书");
do {
System.out.print("请选择: ");
choice = scanner.nextInt();
} while (choice < 1 || choice > 9);
switch (choice) {
case 1:
addBook();
break;
case 2:
removeBook();
break;
case 3:
lendBook();
break;
case 4:
returnBook();
break;
case 5:
getBookById();
break;
case 6:
listBooksByIsbn();
break;
case 7:
listTop10Books();
break;
case 8:
flag = false;
break;
case 9:
listSameType();
break;
}
}
}

private static void addBook() {
System.out.print("编号: ");
int id = scanner.nextInt();
System.out.print("ISBN: ");
String isbn = scanner.next();
System.out.print("书名: ");
String name = scanner.next();
System.out.print("价格: ");
double price = scanner.nextDouble();
System.out.print("作者: ");
String author = scanner.next();
System.out.print("出版社: ");
String publisher = scanner.next();
System.out.print("出版日期: ");
Date pubDate = CommonUtil.stringToDate(scanner.next());
Book book = new Book();
book.setId(id);
book.setIsbn(isbn);
book.setName(name);
book.setPrice(price);
book.setAuthor(author);
book.setPublisher(publisher);
book.setPubDate(pubDate);
if (bookManager.addNewBook(book)) {
System.out.println("新增图书成功!");
} else {
System.out.println("新增图书失败!");
}
}

private static void removeBook() {
System.out.print("编号: ");
int id = scanner.nextInt();
if (bookManager.removeBookById(id)) {
System.out.println("下架成功!");
} else {
System.out.println("下架失败!");
}
}

private static void lendBook() {
System.out.print("图书编号: ");
int bookId = scanner.nextInt();
System.out.print("读者编号: ");
int readerId = scanner.nextInt();
if (bookManager.lendOut(bookId, readerId)) {
System.out.println("借书成功!!!");
} else {
System.out.println("借书失败!!!");
}
}

private static void returnBook() {
System.out.print("图书编号: ");
int bookId = scanner.nextInt();
System.out.print("读者编号: ");
int readerId = scanner.nextInt();
double pulishment = bookManager.returnBack(bookId, readerId);
if (pulishment >= 0) {
System.out.println("还书成功!!!");
if (pulishment > 0) {
System.out.printf("请缴纳罚款: %.1f元\n", pulishment);
}
} else {
System.out.println("还书失败!!!");
}
}

private static void getBookById() {
System.out.print("编号: ");
int id = scanner.nextInt();
Book book = bookManager.searchBookById(id);
displayTitle();
displayBook(book);
}

private static void listBooksByIsbn() {
System.out.print("书名: ");
String name = scanner.next();
List<Book> list = bookManager.searchBookByName(name);
displayBookList(list);
}
private static void listSameType(){
System.out.println("请输入你要查找的图书类型");
String type =scanner.next();
List<Book> list=bookManager.ground(type);
displayBookList(list);
}
private static void listTop10Books() {
List<Book> list = bookManager.searchTop10Books();
displayBookList(list);
}

private static void displayBookList(List<Book> list) {
displayTitle();
for (Book book : list) {
displayBook(book);
}
}

private static void displayTitle() {
System.out.printf("%-50s%-20s%-10s\n", "书名", "作者", "借阅量");
}

private static void displayBook(Book book) {
System.out.printf("%-50s%-20s%-10d\n", book.getName(),
book.getAuthor(), book.getCounter());
}

}