声明:本项目不涉及web操作,但需要了解java的基本语法和MySQL的基本语句运用。
一、项目分布
- db.sql类:SQL语句,在控制台执行,用于建立图书管理库。
- Book类: 定义了书的一些属性(书编号,书名,作者,价格,分类,状态)并且写了属性的get、set、toSting方法。
- User类:定义了用户的一些属性(用户编号,用户名,密码和是否为管理员的标记),并且写了属性的get、set、toSting方法。
- NormalUser类:描述普通用户,实现普通用户的构造方法,并打印普通用户的操作界面。
- Admin类:描述管理员,实现管理员的构造方法并打印管理员的操作界面。
- DBUtil类:封装与数据库建立连接的操作(主要用JDBC来编写)。
- BookDao类:封装 对表的增删查改操作。
- UserDao类:封装 识别用户的操作。
operations包中定义了IOperation(操作)接口,这个包中的下面这些类都实现了这个IOperation接口(完成增删查改等操作):
- AddOperation类:增加书籍
- BorrowOperation类:借阅书籍
- DeleteOperation类:删除书籍
- DisplayOperation类:查看书籍列表
- ExitOperation类:退出系统
- FindOperation类:查找书籍
- ReturnOperation类:返还书籍
二、代码展示
1.SQL语句
在控制台执行,用于建立图书管理库(设置“张三”为普通用户,密码为321;“admin”为管理员,密码为123)
create database if not exists bookmanager; use bookmanager; -- 创建一个书籍表 drop table if exists book; create table book( bookId int primary key auto_increment, name varchar(20), author varchar(20), -- 为了准确,价格以 分 为单位 price int, type varchar(20), -- 如果isBorrowed为1,表示已经借出,为0,表示未借出 isBorrowed int ); -- 创建一个用户表(用户有管理员和普通用户两种) drop table if exists user; create table user( userId int primary key auto_increment, username varchar(20) unique, password varchar(20), -- 如果isAdmin 为1,表示是管理员,为0,表示是普通用户 isAdmin int ); -- 插入一些数据 insert into book values(null,"西游记","吴承恩",10000,"古典小说",0); insert into book values(null, "三国演义", "罗贯中", 10000, "古典小说", 0); insert into book values(null, "水浒传", "施耐庵", 10000, "古典小说", 0); insert into book values(null, "金瓶梅", "兰陵笑笑生", 10000, "古典小说", 0); insert into book values(null,"三体","刘慈欣",10000,"科幻小说",0); -- 插入一些用户 insert into user values(null,"admin","123",1); insert into user values(null,"张三","321",0);
2.Book类
定义了书的一些属性(书编号,书名,作者,价格,分类,状态)并且写了属性的get、set、toSting方法
package Java100_1006; //使用这个类来表示一本书 // +------------+-------------+------+-----+---------+----------------+ // | Field | Type | Null | Key | Default | Extra | // +------------+-------------+------+-----+---------+----------------+ // | bookId | int(11) | NO | PRI | NULL | auto_increment | // | name | varchar(20) | YES | | NULL | | // | author | varchar(20) | YES | | NULL | | // | price | int(11) | YES | | NULL | | // | type | varchar(20) | YES | | NULL | | // | isBorrowed | int(11) | YES | | NULL | | // +------------+-------------+------+-----+---------+----------------+ public class Book { private int bookId; private String name; private String author; private int price; private String type; private boolean isBorrowed; public int getBookId() { return bookId; } public void setBookId(int bookId) { this.bookId = bookId; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } public int getPrice() { return price; } public void setPrice(int price) { this.price = price; } public String getType() { return type; } public void setType(String type) { this.type = type; } public boolean isBorrowed() { return isBorrowed; } public void setBorrowed(boolean borrowed) { isBorrowed = borrowed; } @Override public String toString() { return "Book{" + "bookId=" + bookId + ", name="" + name + """ + ", author="" + author + """ + ", price=" + price + ", type="" + type + """ + ", isBorrowed=" + isBorrowed + "}"; } }
3.User类
定义了用户的一些属性(用户编号,用户名,密码和是否为管理员的标记),并且写了属性的get、set、toSting方法
package Java100_1006; import Java100_1006.operations.IOperation; abstract public class User { // 使用这个 User 类来表示一个用户 // +----------+-------------+------+-----+---------+----------------+ // | Field | Type | Null | Key | Default | Extra | // +----------+-------------+------+-----+---------+----------------+ // | userId | int(11) | NO | PRI | NULL | auto_increment | // | username | varchar(20) | YES | | NULL | | // | password | varchar(20) | YES | | NULL | | // | isAdmin | int(11) | YES | | NULL | | // +----------+-------------+------+-----+---------+----------------+ // 针对此处的 isAdmin, 并不是直接使用一个 boolean 变量来区分, 而是使用两个不同的子类. // 原因是, 管理员和普通用户支持的方法, 是不一样的. private int userId; private String userName; private String passWord; // 包含了一个数组, 数组里面就是该用户支持的哪些操作. // 针对普通用户, 和管理员, 分别设置不同的操作. IOperation[] operations; //普通用户和管理员看到的菜单也不同 abstract public int menu(); public int getUserId() { return userId; } public void setUserId(int userId) { this.userId = userId; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getPassWord() { return passWord; } public void setPassWord(String passWord) { this.passWord = passWord; } @Override public String toString() { return "User{" + "userId=" + userId + ", userName="" + userName + """ + ", passWord="" + passWord + """ + "}"; } }
4.用户分为两种
普通用户和管理员,所以应该分别建立两个类来描述这两个用户。
4.1NormalUser类
**描述普通用户,实现普通用户的构造方法,并打印普通用户的操作界面。
package Java100_1006; import Java100_1006.operations.*; import java.util.Scanner; //普通用户 public class NormalUser extends User{ //普通用户的构造方法 public NormalUser(){ this.operations = new IOperation[]{ //0.退出 new ExitOperation(), //1.查看书籍列表 new DisplayOperation(), //2. 查找指定书籍 new FindOperation(), //3.借阅书籍 new BorrowOperation(), //4. 归还书籍 new ReturnOperation() }; } //打印普通用户的菜单 @Override public int menu() { System.out.println("============================="); System.out.println("欢迎您"+this.getUserName()+"!"); System.out.println("1. 查看书籍列表"); System.out.println("2. 查找指定书籍"); System.out.println("3. 借阅书籍"); System.out.println("4. 归还书籍"); System.out.println("0. 退出系统"); System.out.println("============================="); System.out.println("请输入您的选项:"); Scanner scanner = new Scanner(System.in); int choice = scanner.nextInt(); return choice; } }
4.2Admin类
描述管理员,实现管理员的构造方法并打印管理员的操作界面
package Java100_1006; import Java100_1006.operations.*; import java.util.Scanner; //管理员 public class Admin extends User{ //管理员的构造方法 public Admin(){ //初始化operation //继承与User类,所以可以使用父类的中的数组 this.operations = new IOperation[]{ //0. 退出系统 new ExitOperation(), //1. 查看书籍列表 new DisplayOperation(), //2. 查找指定书籍 new FindOperation(), //3. 新增书籍 new AddOperation(), //4. 删除书籍 new DeleteOperation() }; } //打印管理员的菜单 @Override public int menu() { System.out.println("================================"); System.out.println("欢迎您, " + this.getUserName() + "! 您是管理员! "); System.out.println("1. 查看书籍列表"); System.out.println("2. 查找指定书籍"); System.out.println("3. 新增书籍"); System.out.println("4. 删除书籍"); System.out.println("0. 退出系统"); System.out.println("================================"); System.out.println("请输入选项: "); Scanner scanner = new Scanner(System.in); int choice = scanner.nextInt(); return choice; } }
5.DBUtil类
封装与数据库建立连接的操作(主要用JDBC来编写)
package Java100_1006; import com.mysql.jdbc.jdbc2.optional.MysqlDataSource; import javax.sql.DataSource; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; //先建立这个类来 封装 数据库建立连接的操作 //具体步骤: //1.创建DataSouse实例 //2.根据DataSouse创建对应的Connection public class DBUtil { private static final String URL = "jdbc:mysql://127.0.0.1:3306/bookmanager?characterEncoding=utf8&useSSL=false"; private static final String USERNAME = "root"; private static final String PASSWORD = "1234"; //懒汉模式: private static DataSource dataSource = null; //初始情况下,dataSource为null,没有被实例化 //首次调用getDataSource()时才会被实例化 private static DataSource getDataSource(){ if(dataSource == null){ dataSource = new MysqlDataSource(); ((MysqlDataSource)dataSource).setUrl(URL); ((MysqlDataSource)dataSource).setUser(USERNAME); ((MysqlDataSource)dataSource).setPassword(PASSWORD); } return dataSource; } //提供一个方法来建立连接 //用static来修饰,那么就无需实例化DBUtil实例就能调用这个方法,更加方便 public static Connection getConnection() throws SQLException { return getDataSource().getConnection(); } //释放资源 public static void close(Connection connection, PreparedStatement statement, ResultSet resultSet){ try{ if(resultSet != null){ resultSet.close(); } if(statement != null){ statement.close(); } if(connection != null){ connection.close(); } }catch (SQLException e){ e.printStackTrace(); } } }
6.BookDao类
封装 对表的增删查改操作
package Java100_1006; import Java100_1006.Book; import Java100_1006.DBUtil; import java.sql.*; import java.util.ArrayList; import java.util.List; //封装 对Book表的增删查改操作 public class BookDao { //1.新增书籍(插入) public boolean add(Book book){ //把book对象插入数据库的书籍表中 Connection connection = null; PreparedStatement statement = null; try { //1.和数据库建立连接 connection = DBUtil.getConnection(); //2.拼装sql语句 String sql = "insert into book values(null,?,?,?,?,?)"; statement = connection.prepareStatement(sql); statement.setString(1,book.getName()); statement.setString(2,book.getAuthor()); statement.setInt(3,book.getPrice()); statement.setString(4,book.getType()); statement.setInt(5,book.isBorrowed()?1:0); //3.执行SQL int ret = statement.executeUpdate(); if(ret == 1) return true; return false; }catch (SQLException e){ e.printStackTrace(); }finally { DBUtil.close(connection,statement,null); } return false; } //2.查找所有书籍(查找) public List<Book> selectAll() { List<Book> list = new ArrayList<>(); Connection connection = null; PreparedStatement statement = null; ResultSet resultSet = null; try { //1.与数据库建立连接 connection = DBUtil.getConnection(); //2.拼装SQL String sql = "select * from book"; statement = connection.prepareStatement(sql); //3.执行SQL resultSet = statement.executeQuery(); //4.遍历结果集合 while(resultSet.next()){ //取出当前行的这些列,构造一个Book对象来 Book book = new Book(); book.setBookId(resultSet.getInt("bookId")); book.setName(resultSet.getString("name")); book.setAuthor(resultSet.getString("author")); book.setPrice(resultSet.getInt("price")); book.setType(resultSet.getString("type")); book.setBorrowed(resultSet.getInt("isBorrowed")==1); //把这个book对象添加到链表中 list.add(book); } } catch (SQLException e) { e.printStackTrace(); }finally { DBUtil.close(connection,statement,resultSet); } return list; } //3.根据名字查找书籍(查找) public List<Book> selectByName(String name){ List<Book> list = new ArrayList<>(); Connection connection = null; PreparedStatement statement = null; ResultSet resultSet = null; try { //1.先与数据库建立连接 connection = DBUtil.getConnection(); //2.拼装SQL语句 String sql = "select * from book where name=?"; statement = connection.prepareStatement(sql); statement.setString(1,name); //3.执行SQL resultSet = statement.executeQuery(); //4.遍历结果集合 while(resultSet.next()){ Book book = new Book(); book.setBookId(resultSet.getInt("bookId")); book.setName(resultSet.getString("name")); book.setAuthor(resultSet.getString("author")); book.setPrice(resultSet.getInt("price")); book.setType(resultSet.getString("type")); book.setBorrowed(resultSet.getInt("isBorrowed") == 1); list.add(book); } } catch (SQLException e) { e.printStackTrace(); }finally { DBUtil.close(connection,statement,resultSet); } return list; } //4.删除书籍(删除) public boolean delete(int bookId){ Connection connection = null; PreparedStatement statement = null; try { //1.建立连接 connection = DBUtil.getConnection(); //2.拼装SQL String sql = "delete from book where bookId=?"; statement = connection.prepareStatement(sql); statement.setInt(1,bookId); //3.执行SQL int ret = statement.executeUpdate(); if(ret != 1){ return false; } return true; } catch (SQLException e) { e.printStackTrace(); }finally { DBUtil.close(connection,statement,null); } return false; } //5.借书(修改) public boolean borrowBook(int bookId){ Connection connection = null; //statement1用于查找操作 PreparedStatement statement1 = null; //statement2用于修改操作 PreparedStatement statement2 = null; ResultSet resultSet = null; try { //1.建立连接 connection = DBUtil.getConnection(); //要借书,就必须知道这本书存不存在,所以我们先查找,再操作 //2.拼装SQL String sql = "select * from book where bookId=?"; statement1 = connection.prepareStatement(sql); statement1.setInt(1,bookId); //3.执行SQL resultSet = statement1.executeQuery(); //4.遍历结果,预期结果要么是1条,要么是0条 if(resultSet.next()){ //进入if就说明书是存在的 boolean isBorrowed = (resultSet.getInt("isBorrowed")==1); if(isBorrowed) { //说明书已经被借出了,不能再次借阅 System.out.println("书已经借出! 无法再次借出! bookId = " + bookId); return false; } }else{ //进入else,那么书是不存在的 System.out.println("书不存在! 无法借出! bookId = " + bookId); return false; } //[接下来是开始进行借书逻辑] //5.拼装SQL sql = "update book set isBorrowed=1 where bookId=?"; statement2 = connection.prepareStatement(sql); statement2.setInt(1,bookId); //6.执行SQL int ret = statement2.executeUpdate(); if(ret != 1){ return false; } return true; } catch (SQLException e) { e.printStackTrace(); }finally { if(resultSet != null){ try { resultSet.close(); } catch (SQLException e) { e.printStackTrace(); } } if(statement2 != null){ try { statement2.close(); } catch (SQLException e) { e.printStackTrace(); } } if(statement1 != null){ try { statement1.close(); } catch (SQLException e) { e.printStackTrace(); } } if (connection != null){ try { connection.close(); } catch (SQLException e) { e.printStackTrace(); } } } return false; } //6.还书(修改) public boolean returnBook(int bookId){ Connection connection = null; PreparedStatement statement1 = null; PreparedStatement statement2 = null; ResultSet resultSet = null; try { connection = DBUtil.getConnection(); //查询书是否存在 String sql = "select * from book where bookId=?"; statement1 = connection.prepareStatement(sql); statement1.setInt(1,bookId); resultSet = statement1.executeQuery(); if(resultSet.next()){ //进入if语句就说明这本书存在于书籍名单中 boolean isBorrowed = (resultSet.getInt("isBorrowed")==1); if(!isBorrowed){ System.out.println("书没有借出, 没必要还! bookId = " + bookId); return false; } }else{ //不是图书系统中的书,不需要还 System.out.println("书不存在, 无法归还! bookId = " + bookId); return false; } //[还书] //修改书籍的借出状态就可 sql = "update book set isBorrowed=0 where bookId=?"; statement2 = connection.prepareStatement(sql); statement2.setInt(1,bookId); int ret = statement2.executeUpdate(); if(ret != 1){ return false; } return true; } catch (SQLException e) { e.printStackTrace(); }finally { if(resultSet != null){ try { resultSet.close(); } catch (SQLException e) { e.printStackTrace(); } } if(statement2 != null){ try { statement2.close(); } catch (SQLException e) { e.printStackTrace(); } } if(statement1 != null){ try { statement1.close(); } catch (SQLException e) { e.printStackTrace(); } } if (connection != null){ try { connection.close(); } catch (SQLException e) { e.printStackTrace(); } } } return false; } }
7.UserDao类
封装 识别用户的操作
package Java100_1006; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class UserDao { //实现根据用户名找密码这样一个过程(用户名 唯一) public User selectByName(String name){ Connection connection = null; PreparedStatement statement = null; ResultSet resultSet = null; try { connection = DBUtil.getConnection(); String sql = "select * from user where username=?"; statement = connection.prepareStatement(sql); statement.setString(1,name); resultSet = statement.executeQuery(); if(resultSet.next()){ //存在这个用户,返回一个User对象 //判断这个用户是普通用户还是管理员 boolean isAdmin = (resultSet.getInt("isAdmin"))==1; User user = null; if (isAdmin){ user = new Admin(); }else{ user = new NormalUser(); } user.setUserId(resultSet.getInt("userId")); user.setUserName(resultSet.getString("username")); user.setPassWord(resultSet.getString("password")); return user; } } catch (SQLException e) { e.printStackTrace(); }finally { DBUtil.close(connection,statement,resultSet); } return null; } }
8.operations包
创建IOperation接口和实现这个接口的其他类
接口:
package Java100_1006.operations; //后续的增加 删除 借书 还书 等操作都要实现这个接口 public interface IOperation { void work(); }
8.1AddOperation类:增加书籍
package Java100_1006.operations; import Java100_1006.Book; import Java100_1006.BookDao; import java.util.Scanner; public class AddOperation implements IOperation{ @Override public void work() { System.out.println("新增书籍!"); Scanner scanner = new Scanner(System.in); System.out.println("请输入书名: "); String bookName = scanner.next(); System.out.println("请输入作者: "); String author = scanner.next(); System.out.println("请输入价格:"); int price = scanner.nextInt(); System.out.println("请输入类别:"); String type = scanner.next(); //假设新增书籍都是未借出的状态 Book book = new Book(); book.setName(bookName); book.setAuthor(author); book.setPrice(price); book.setType(type); BookDao bookDao = new BookDao(); boolean ret = bookDao.add(book); if(ret){ System.out.println("新增书籍成功"); }else{ System.out.println("新增书籍失败!"); } } }
8.2BorrowOperation类:借阅书籍
package Java100_1006.operations; import Java100_1006.BookDao; import java.util.Scanner; public class BorrowOperation implements IOperation{ @Override public void work() { System.out.println("借阅书籍!"); Scanner scanner = new Scanner(System.in); System.out.println("请输入要借阅的书籍id:"); int bookId = scanner.nextInt(); BookDao bookDao = new BookDao(); boolean ret = bookDao.borrowBook(bookId); if (ret) { System.out.println("借阅书籍成功!"); } else { System.out.println("借阅书籍失败!"); } } }
8.3DeleteOperation类:删除书籍
package Java100_1006.operations; import Java100_1006.BookDao; import java.util.Scanner; public class DeleteOperation implements IOperation{ @Override public void work() { System.out.println("删除书籍!"); Scanner scanner = new Scanner(System.in); System.out.println("请输入要删除的书籍id: "); int bookId = scanner.nextInt(); BookDao bookDao = new BookDao(); boolean ret = bookDao.delete(bookId); if (ret) { System.out.println("删除成功!"); } else { System.out.println("删除失败!"); } } }
8.4DisplayOperation类:查看书籍列表
package Java100_1006.operations; import Java100_1006.Book; import Java100_1006.BookDao; import java.util.List; public class DisplayOperation implements IOperation{ @Override public void work() { System.out.println("展示所有书籍!"); BookDao bookDao = new BookDao(); List<Book> books = bookDao.selectAll(); for(Book book:books){ System.out.println(book); } System.out.println("展示所有书籍完毕!"); } }
8.5ExitOperation类:退出系统
package Java100_1006.operations; //退出操作 public class ExitOperation implements IOperation{ @Override public void work() { System.out.println("退出程序"); System.exit(0); } }
8.6FindOperation类:查找书籍
package Java100_1006.operations; import Java100_1006.Book; import Java100_1006.BookDao; import java.util.ArrayList; import java.util.List; import java.util.Scanner; public class FindOperation implements IOperation{ @Override public void work() { System.out.println("根据名字查找书籍!"); System.out.println("请输入要查找的书名: "); Scanner scanner = new Scanner(System.in); String bookName = scanner.next(); BookDao bookDao = new BookDao(); List<Book> books = bookDao.selectByName(bookName); for(Book book:books){ System.out.println(book); } System.out.println("根据名字查找书籍完毕!"); } }
8.7ReturnOperation类:返还书籍
package Java100_1006.operations; import Java100_1006.BookDao; import java.util.Scanner; public class ReturnOperation implements IOperation{ @Override public void work() { System.out.println("归还书籍!"); Scanner scanner = new Scanner(System.in); System.out.println("请输入要归还的书籍id:"); int bookId = scanner.nextInt(); BookDao bookDao = new BookDao(); boolean ret = bookDao.returnBook(bookId); if (ret) { System.out.println("归还书籍成功!"); } else { System.out.println("归还书籍失败!"); } } }
9.Main方法实现
package Java100_1006; import java.util.Scanner; //编写系统的主体逻辑 public class Main { public static void main(String[] args) { //通过login方法进行登录 User user = login(); while(true){ int choice = user.menu(); user.doOperation(choice); } } private static User login() { //1.实现用户登录逻辑 Scanner scanner = new Scanner(System.in); System.out.println("请输入用户名:"); String userName = scanner.next(); System.out.println("请输入密码:"); String passWord = scanner.next(); //2.从数据库根据用户名查询密码 UserDao userDao = new UserDao(); User user = userDao.selectByName(userName); if(user == null){ //不存在该用户 System.out.println("登陆失败!"); // 直接退出程序 System.exit(0); } if(!user.getPassWord().equals(passWord)){ //密码不正确 System.out.println("登陆失败"); System.exit(0); } return user; } }
三、结果实现
1.登录界面
2.普通用户操作
3.管理员操作
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原文链接:https://blog.csdn.net/m0_52373742/article/details/120643067