Java開發實例之圖書管理系統的實現
聲明:本項目不涉及web操作,但需要瞭解java的基本語法和MySQL的基本語句運用。
一、項目分佈
- db.sql類:SQL語句,在控制臺執行,用於建立圖書管理庫。
- Book類: 定義瞭書的一些屬性(書編號,書名,作者,價格,分類,狀態)並且寫瞭屬性的get、set、toSting方法。
- User類:定義瞭用戶的一些屬性(用戶編號,用戶名,密碼和是否為管理員的標記),並且寫瞭屬性的get、set、toSting方法。
- NormalUser類:描述普通用戶,實現普通用戶的構造方法,並打印普通用戶的操作界面。
- Admin類:描述管理員,實現管理員的構造方法並打印管理員的操作界面。
- DBUtil類:封裝與數據庫建立連接的操作(主要用JDBC來編寫)。
- BookDao類:封裝 對表的增刪查改操作。
- UserDao類:封裝 識別用戶的操作。
operations包中定義瞭IOperation(操作)接口,這個包中的下面這些類都實現瞭這個IOperation接口(完成增刪查改等操作):
- AddOperation類:增加書籍
- BorrowOperation類:借閱書籍
- DeleteOperation類:刪除書籍
- DisplayOperation類:查看書籍列表
- ExitOperation類:退出系統
- FindOperation類:查找書籍
- ReturnOperation類:返還書籍
二、代碼展示
1.SQL語句
在控制臺執行,用於建立圖書管理庫(設置“張三”為普通用戶,密碼為321;“admin”為管理員,密碼為123)
create database if not exists bookmanager; use bookmanager; -- 創建一個書籍表 drop table if exists book; create table book( bookId int primary key auto_increment, name varchar(20), author varchar(20), -- 為瞭準確,價格以 分 為單位 price int, type varchar(20), -- 如果isBorrowed為1,表示已經借出,為0,表示未借出 isBorrowed int ); -- 創建一個用戶表(用戶有管理員和普通用戶兩種) drop table if exists user; create table user( userId int primary key auto_increment, username varchar(20) unique, password varchar(20), -- 如果isAdmin 為1,表示是管理員,為0,表示是普通用戶 isAdmin int ); -- 插入一些數據 insert into book values(null,'西遊記','吳承恩',10000,'古典小說',0); insert into book values(null, '三國演義', '羅貫中', 10000, '古典小說', 0); insert into book values(null, '水滸傳', '施耐庵', 10000, '古典小說', 0); insert into book values(null, '金瓶梅', '蘭陵笑笑生', 10000, '古典小說', 0); insert into book values(null,'三體','劉慈欣',10000,'科幻小說',0); -- 插入一些用戶 insert into user values(null,'admin','123',1); insert into user values(null,'張三','321',0);
2.Book類
定義瞭書的一些屬性(書編號,書名,作者,價格,分類,狀態)並且寫瞭屬性的get、set、toSting方法
package Java100_1006; //使用這個類來表示一本書 // +------------+-------------+------+-----+---------+----------------+ // | 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類
定義瞭用戶的一些屬性(用戶編號,用戶名,密碼和是否為管理員的標記),並且寫瞭屬性的get、set、toSting方法
package Java100_1006; import Java100_1006.operations.IOperation; abstract public class User { // 使用這個 User 類來表示一個用戶 // +----------+-------------+------+-----+---------+----------------+ // | 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 | | // +----------+-------------+------+-----+---------+----------------+ // 針對此處的 isAdmin, 並不是直接使用一個 boolean 變量來區分, 而是使用兩個不同的子類. // 原因是, 管理員和普通用戶支持的方法, 是不一樣的. private int userId; private String userName; private String passWord; // 包含瞭一個數組, 數組裡面就是該用戶支持的哪些操作. // 針對普通用戶, 和管理員, 分別設置不同的操作. IOperation[] operations; //普通用戶和管理員看到的菜單也不同 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.用戶分為兩種
普通用戶和管理員,所以應該分別建立兩個類來描述這兩個用戶。
4.1NormalUser類
**描述普通用戶,實現普通用戶的構造方法,並打印普通用戶的操作界面。
package Java100_1006; import Java100_1006.operations.*; import java.util.Scanner; //普通用戶 public class NormalUser extends User{ //普通用戶的構造方法 public NormalUser(){ this.operations = new IOperation[]{ //0.退出 new ExitOperation(), //1.查看書籍列表 new DisplayOperation(), //2. 查找指定書籍 new FindOperation(), //3.借閱書籍 new BorrowOperation(), //4. 歸還書籍 new ReturnOperation() }; } //打印普通用戶的菜單 @Override public int menu() { System.out.println("============================="); System.out.println("歡迎您"+this.getUserName()+"!"); System.out.println("1. 查看書籍列表"); System.out.println("2. 查找指定書籍"); System.out.println("3. 借閱書籍"); System.out.println("4. 歸還書籍"); System.out.println("0. 退出系統"); System.out.println("============================="); System.out.println("請輸入您的選項:"); Scanner scanner = new Scanner(System.in); int choice = scanner.nextInt(); return choice; } }
4.2Admin類
描述管理員,實現管理員的構造方法並打印管理員的操作界面
package Java100_1006; import Java100_1006.operations.*; import java.util.Scanner; //管理員 public class Admin extends User{ //管理員的構造方法 public Admin(){ //初始化operation //繼承與User類,所以可以使用父類的中的數組 this.operations = new IOperation[]{ //0. 退出系統 new ExitOperation(), //1. 查看書籍列表 new DisplayOperation(), //2. 查找指定書籍 new FindOperation(), //3. 新增書籍 new AddOperation(), //4. 刪除書籍 new DeleteOperation() }; } //打印管理員的菜單 @Override public int menu() { System.out.println("================================"); System.out.println("歡迎您, " + this.getUserName() + "! 您是管理員! "); System.out.println("1. 查看書籍列表"); System.out.println("2. 查找指定書籍"); System.out.println("3. 新增書籍"); System.out.println("4. 刪除書籍"); System.out.println("0. 退出系統"); System.out.println("================================"); System.out.println("請輸入選項: "); Scanner scanner = new Scanner(System.in); int choice = scanner.nextInt(); return choice; } }
5.DBUtil類
封裝與數據庫建立連接的操作(主要用JDBC來編寫)
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; //先建立這個類來 封裝 數據庫建立連接的操作 //具體步驟: //1.創建DataSouse實例 //2.根據DataSouse創建對應的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"; //懶漢模式: private static DataSource dataSource = null; //初始情況下,dataSource為null,沒有被實例化 //首次調用getDataSource()時才會被實例化 private static DataSource getDataSource(){ if(dataSource == null){ dataSource = new MysqlDataSource(); ((MysqlDataSource)dataSource).setUrl(URL); ((MysqlDataSource)dataSource).setUser(USERNAME); ((MysqlDataSource)dataSource).setPassword(PASSWORD); } return dataSource; } //提供一個方法來建立連接 //用static來修飾,那麼就無需實例化DBUtil實例就能調用這個方法,更加方便 public static Connection getConnection() throws SQLException { return getDataSource().getConnection(); } //釋放資源 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類
封裝 對表的增刪查改操作
package Java100_1006; import Java100_1006.Book; import Java100_1006.DBUtil; import java.sql.*; import java.util.ArrayList; import java.util.List; //封裝 對Book表的增刪查改操作 public class BookDao { //1.新增書籍(插入) public boolean add(Book book){ //把book對象插入數據庫的書籍表中 Connection connection = null; PreparedStatement statement = null; try { //1.和數據庫建立連接 connection = DBUtil.getConnection(); //2.拼裝sql語句 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.執行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.查找所有書籍(查找) public List<Book> selectAll() { List<Book> list = new ArrayList<>(); Connection connection = null; PreparedStatement statement = null; ResultSet resultSet = null; try { //1.與數據庫建立連接 connection = DBUtil.getConnection(); //2.拼裝SQL String sql = "select * from book"; statement = connection.prepareStatement(sql); //3.執行SQL resultSet = statement.executeQuery(); //4.遍歷結果集合 while(resultSet.next()){ //取出當前行的這些列,構造一個Book對象來 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); //把這個book對象添加到鏈表中 list.add(book); } } catch (SQLException e) { e.printStackTrace(); }finally { DBUtil.close(connection,statement,resultSet); } return list; } //3.根據名字查找書籍(查找) public List<Book> selectByName(String name){ List<Book> list = new ArrayList<>(); Connection connection = null; PreparedStatement statement = null; ResultSet resultSet = null; try { //1.先與數據庫建立連接 connection = DBUtil.getConnection(); //2.拼裝SQL語句 String sql = "select * from book where name=?"; statement = connection.prepareStatement(sql); statement.setString(1,name); //3.執行SQL resultSet = statement.executeQuery(); //4.遍歷結果集合 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.刪除書籍(刪除) public boolean delete(int bookId){ Connection connection = null; PreparedStatement statement = null; try { //1.建立連接 connection = DBUtil.getConnection(); //2.拼裝SQL String sql = "delete from book where bookId=?"; statement = connection.prepareStatement(sql); statement.setInt(1,bookId); //3.執行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.借書(修改) public boolean borrowBook(int bookId){ Connection connection = null; //statement1用於查找操作 PreparedStatement statement1 = null; //statement2用於修改操作 PreparedStatement statement2 = null; ResultSet resultSet = null; try { //1.建立連接 connection = DBUtil.getConnection(); //要借書,就必須知道這本書存不存在,所以我們先查找,再操作 //2.拼裝SQL String sql = "select * from book where bookId=?"; statement1 = connection.prepareStatement(sql); statement1.setInt(1,bookId); //3.執行SQL resultSet = statement1.executeQuery(); //4.遍歷結果,預期結果要麼是1條,要麼是0條 if(resultSet.next()){ //進入if就說明書是存在的 boolean isBorrowed = (resultSet.getInt("isBorrowed")==1); if(isBorrowed) { //說明書已經被借出瞭,不能再次借閱 System.out.println("書已經借出! 無法再次借出! bookId = " + bookId); return false; } }else{ //進入else,那麼書是不存在的 System.out.println("書不存在! 無法借出! bookId = " + bookId); return false; } //[接下來是開始進行借書邏輯] //5.拼裝SQL sql = "update book set isBorrowed=1 where bookId=?"; statement2 = connection.prepareStatement(sql); statement2.setInt(1,bookId); //6.執行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.還書(修改) public boolean returnBook(int bookId){ Connection connection = null; PreparedStatement statement1 = null; PreparedStatement statement2 = null; ResultSet resultSet = null; try { connection = DBUtil.getConnection(); //查詢書是否存在 String sql = "select * from book where bookId=?"; statement1 = connection.prepareStatement(sql); statement1.setInt(1,bookId); resultSet = statement1.executeQuery(); if(resultSet.next()){ //進入if語句就說明這本書存在於書籍名單中 boolean isBorrowed = (resultSet.getInt("isBorrowed")==1); if(!isBorrowed){ System.out.println("書沒有借出, 沒必要還! bookId = " + bookId); return false; } }else{ //不是圖書系統中的書,不需要還 System.out.println("書不存在, 無法歸還! bookId = " + bookId); return false; } //[還書] //修改書籍的借出狀態就可 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類
封裝 識別用戶的操作
package Java100_1006; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class UserDao { //實現根據用戶名找密碼這樣一個過程(用戶名 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()){ //存在這個用戶,返回一個User對象 //判斷這個用戶是普通用戶還是管理員 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
創建IOperation接口和實現這個接口的其他類
接口:
package Java100_1006.operations; //後續的增加 刪除 借書 還書 等操作都要實現這個接口 public interface IOperation { void work(); }
8.1AddOperation類:增加書籍
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("新增書籍!"); Scanner scanner = new Scanner(System.in); System.out.println("請輸入書名: "); String bookName = scanner.next(); System.out.println("請輸入作者: "); String author = scanner.next(); System.out.println("請輸入價格:"); int price = scanner.nextInt(); System.out.println("請輸入類別:"); String type = scanner.next(); //假設新增書籍都是未借出的狀態 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("新增書籍成功"); }else{ System.out.println("新增書籍失敗!"); } } }
8.2BorrowOperation類:借閱書籍
package Java100_1006.operations; import Java100_1006.BookDao; import java.util.Scanner; public class BorrowOperation implements IOperation{ @Override public void work() { System.out.println("借閱書籍!"); Scanner scanner = new Scanner(System.in); System.out.println("請輸入要借閱的書籍id:"); int bookId = scanner.nextInt(); BookDao bookDao = new BookDao(); boolean ret = bookDao.borrowBook(bookId); if (ret) { System.out.println("借閱書籍成功!"); } else { System.out.println("借閱書籍失敗!"); } } }
8.3DeleteOperation類:刪除書籍
package Java100_1006.operations; import Java100_1006.BookDao; import java.util.Scanner; public class DeleteOperation implements IOperation{ @Override public void work() { System.out.println("刪除書籍!"); Scanner scanner = new Scanner(System.in); System.out.println("請輸入要刪除的書籍id: "); int bookId = scanner.nextInt(); BookDao bookDao = new BookDao(); boolean ret = bookDao.delete(bookId); if (ret) { System.out.println("刪除成功!"); } else { System.out.println("刪除失敗!"); } } }
8.4DisplayOperation類:查看書籍列表
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("展示所有書籍!"); BookDao bookDao = new BookDao(); List<Book> books = bookDao.selectAll(); for(Book book:books){ System.out.println(book); } System.out.println("展示所有書籍完畢!"); } }
8.5ExitOperation類:退出系統
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類:查找書籍
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("根據名字查找書籍!"); System.out.println("請輸入要查找的書名: "); 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("根據名字查找書籍完畢!"); } }
8.7ReturnOperation類:返還書籍
package Java100_1006.operations; import Java100_1006.BookDao; import java.util.Scanner; public class ReturnOperation implements IOperation{ @Override public void work() { System.out.println("歸還書籍!"); Scanner scanner = new Scanner(System.in); System.out.println("請輸入要歸還的書籍id:"); int bookId = scanner.nextInt(); BookDao bookDao = new BookDao(); boolean ret = bookDao.returnBook(bookId); if (ret) { System.out.println("歸還書籍成功!"); } else { System.out.println("歸還書籍失敗!"); } } }
9.Main方法實現
package Java100_1006; import java.util.Scanner; //編寫系統的主體邏輯 public class Main { public static void main(String[] args) { //通過login方法進行登錄 User user = login(); while(true){ int choice = user.menu(); user.doOperation(choice); } } private static User login() { //1.實現用戶登錄邏輯 Scanner scanner = new Scanner(System.in); System.out.println("請輸入用戶名:"); String userName = scanner.next(); System.out.println("請輸入密碼:"); String passWord = scanner.next(); //2.從數據庫根據用戶名查詢密碼 UserDao userDao = new UserDao(); User user = userDao.selectByName(userName); if(user == null){ //不存在該用戶 System.out.println("登陸失敗!"); // 直接退出程序 System.exit(0); } if(!user.getPassWord().equals(passWord)){ //密碼不正確 System.out.println("登陸失敗"); System.exit(0); } return user; } }
三、結果實現
1.登錄界面
2.普通用戶操作
3.管理員操作
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