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Come on 馆长~~~~~

图书馆管理系统

明确对像

  • 书
  • 用户 - - - - - - 管理员用户 + 普通用户
  • 书架（即数据库） - - - - - - 书表 + 用户表

明确对象结构

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明确需求

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建表

drop table if exists book;
drop table if exists user;
create table book(bookId int primary key auto_increment, 
                  name varchar(20), 
                  author varchar(20),
                  type varchar(20),--1表示已借出,0表示未借出
                  isBorrowed int);
create table user(userId int primary key auto_increment, 
                  name varchar(20) unique,
                  password varchar(20),--1表示是管理员，0表示不是管理员
                  isAmin int);

insert into book values(null,"西游记","吴承恩","神话小说",0);
insert into book values(null,"平凡的世界","路遥","陕北风情",0);
insert into user values(null,"东仔","1234",1);
insert into user values(null,"辉仔","1234",0);

创建对象

  • Book类
/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 强仔
 * Date: 2022-01-26
 * Time: 16:08
 */
public class Book {
    private int bookId;
    private String name;
    private String author;
    private String type;
    private boolean isBorrowed;

    public intgetBookId(){return bookId;}

    public voidsetBookId(int bookId){
        this.bookId = bookId;}

    public String getName(){return name;}

    public voidsetName(String name){
        this.name = name;}

    public String getAuthor(){return author;}

    public voidsetAuthor(String author){
        this.author = author;}

    public String getType(){return type;}

    public voidsetType(String type){
        this.type = type;}

    public boolean isBorrowed(){return isBorrowed;}

    public voidsetBorrowed(boolean borrowed){
        isBorrowed = borrowed;}

    @Override
    public String toString(){return"Book{"+"bookId="+ bookId +", name='"+ name +'\''+", author='"+ author +'\''+", type='"+ type +'\''+", isBorrowed="+ isBorrowed +'}';}}
  • User类 不需要创建实例，所以User可以创建成抽象类 其子类为 NormalUser 和 Amin，只需要其子类创建实例即可 子类不需要继承User的成员变量，只需要重写其work()方法即可
abstract public class User {
    private int userId;
    private String name;
    private String password;
    boolean isAmin;

    Operation[] operations = null;

    abstract public voidwork();
    
    public intgetUserId(){return userId;}

    public voidsetUserId(int userId){
        this.userId = userId;}

    public String getName(){return name;}

    public voidsetName(String name){
        this.name = name;}

    public String getPassword(){return password;}

    public voidsetPassword(String password){
        this.password = password;}
    public boolean isAmin(){return isAmin;}

    public voidsetAmin(boolean amin){
        isAmin = amin;}

    @Override
    public String toString(){return"User{"+"userId="+ userId +", name='"+ name +'\''+", isAmin="+ isAmin +", operations="+ Arrays.toString(operations)+'}';}}
  • Amin类
public class Amin extends User{//可进行的操作
    Operation[] operations ={
            new ExitOp(),
            new SelectOp(),
            new SelectByNameOp(),
            new InsertOp(),
            new DeleteOp()};
    @Override
    voidwork(){}}
  • NormalUser类
public class NormalUser extends User{//可进行的操作
    Operation[] operations ={
            new ExitOp(),
            new SelectOp(),
            new SelectByNameOp(),
            new BorrowOp(),
            new ReturnOp()};
    @Override
    voidwork(){}}
  • Operation接口及实现此接口的操作类
public interface Operation {voidoperate();}

在这里插入图片描述

  • DBUtil类 把数据库的 连接和创建sql语句 操作封装一下 一个工程只要一个数据源就好
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;

public class DBUtil {
    private static String url ="jdbc:mysql://127.0.0.1:3306/bookmanage?characterEncoding=utf8&useSSL=false";
    private static String userName ="root";
    private static String password ="cuige2001";

    private static DataSource dataSource = new MysqlDataSource();
    private Connection connection = null;//静态代码块  类加载时执行，只执行一次，在main方法前//1.创建数据库源static{((MysqlDataSource) dataSource).setUrl(url);((MysqlDataSource) dataSource).setUser(userName);((MysqlDataSource) dataSource).setPassword(password);}//实例代码块  构造方法执行前执行，构造方法执行多少次，它就执行多少次//2.建立连接{
        try {
            connection = dataSource.getConnection();}catch(SQLException e){
            e.printStackTrace();}}//3.构造sql语句
    public PreparedStatement preparedStatement(String sql) throws SQLException {return connection.prepareStatement(sql);}//5.释放资源
    public voidclose(PreparedStatement statement, ResultSet resultSet){if(resultSet != null){
            try {
                resultSet.close();}catch(SQLException e){
                e.printStackTrace();}}if(statement != null){
            try {
                statement.close();}catch(SQLException e){
                e.printStackTrace();}}

        try {
            connection.close();}catch(SQLException e){
            e.printStackTrace();}}}
  • BookDao类 对数据库书表的所有操作

注意
resultSet.next() 和 resultSet == null 的区别

ResultSet resultSet 
resultSet.next()//false
resultSet == null    // false

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class BookDao {//新增书籍
    public static boolean Insert(Book book){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        try {
            String sql ="insert into book values(null,?,?,?,0)";
            statement = dbUtil.preparedStatement(sql);
            statement.setString(1, book.getName());
            statement.setString(2, book.getAuthor());
            statement.setString(3, book.getType());int ret = statement.executeUpdate();return ret ==1;}catch(SQLException e){
            e.printStackTrace();} finally {
            dbUtil.close(statement, null);}return false;}//查看所有书籍
    public staticvoidSelect(){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            String sql ="select * from book";
            statement = dbUtil.preparedStatement(sql);
            resultSet = statement.executeQuery();while(resultSet.next()){
                Book book = new Book();
                book.setBookId(resultSet.getInt("bookId"));
                book.setName(resultSet.getString("name"));
                book.setAuthor(resultSet.getString("author"));
                book.setType(resultSet.getString("type"));
                boolean ret = resultSet.getInt("isBorrowed")==1;
                book.setBorrowed(ret);
                System.out.println(book);}}catch(SQLException e){
            e.printStackTrace();} finally {
            dbUtil.close(statement, resultSet);}}//根据书名查找书籍
    public staticvoidSelectByName(String name){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        ResultSet resultSet = null;

        try {
            String sql ="select * from book where name = ?";
            statement = dbUtil.preparedStatement(sql);
            statement.setString(1, name);
            resultSet = statement.executeQuery();//标记
            boolean sign = true;while(resultSet.next()){
                sign = false;

                Book book = new Book();
                book.setBookId(resultSet.getInt("bookId"));
                book.setName(resultSet.getString("name"));
                book.setAuthor(resultSet.getString("author"));
                book.setType(resultSet.getString("type"));
                boolean ret = resultSet.getInt("isBorrowed")==1;
                book.setBorrowed(ret);
                System.out.println(book);}if(sign){
                System.out.println("查无此书！！！");}}catch(SQLException e){
            e.printStackTrace();} finally {
            dbUtil.close(statement, resultSet);}}//删除书籍
    public static boolean Delete(int bookId){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        try {
            String sql ="delete from book where bookId = ?";
            statement = dbUtil.preparedStatement(sql);
            statement.setInt(1, bookId);int ret = statement.executeUpdate();if(ret ==1){
                System.out.println("删除成功！！！");return true;}else{
                System.out.println("删除失败，没有此书！！！");return false;}}catch(SQLException e){
            e.printStackTrace();} finally {
            dbUtil.close(statement, null);}return false;}//借书
    public static boolean Borrow(int bookId){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        PreparedStatement statement2 = null;
        ResultSet resultSet = null;
        try {
            String sql ="select * from book where bookId = ?";
            statement = dbUtil.preparedStatement(sql);
            statement.setInt(1,bookId);
            resultSet = statement.executeQuery();if(resultSet.next()){
                boolean isBorrowed = resultSet.getInt("isBorrowed")==1;if(isBorrowed){
                    System.out.println("已经借出去了！！！");return false;}else{
                    String str ="Update book set isBorrowed = 1 where bookId = ?";
                    statement2 = dbUtil.preparedStatement(str);
                    statement2.setInt(1,bookId);
                    statement2.executeUpdate();
                    System.out.println("借书成功！！！");return true;}}else{
                System.out.println("没有此书！！！");return false;}}catch(SQLException e){
            e.printStackTrace();} finally {if(statement2 != null){
                try {
                    statement2.close();}catch(SQLException e){
                    e.printStackTrace();}}
            dbUtil.close(statement, resultSet);}return false;}//还书
    public static boolean Return(int bookId){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        PreparedStatement statement2 = null;
        ResultSet resultSet = null;
        try {
            String sql ="select * from book where bookId = ?";
            statement = dbUtil.preparedStatement(sql);
            statement.setInt(1,bookId);
            resultSet = statement.executeQuery();if(resultSet.next()){
                boolean isBorrowed = resultSet.getInt("isBorrowed")==1;if(!isBorrowed){
                    System.out.println("此书已还！！！");return false;}else{
                    String str ="Update book set isBorrowed = 0 where bookId = ?";
                    statement2 = dbUtil.preparedStatement(str);
                    statement2.setInt(1,bookId);
                    statement2.executeUpdate();
                    System.out.println("还书成功！！！");return true;}}else{
                System.out.println("没有此书！！！");return false;}}catch(SQLException e){
            e.printStackTrace();} finally {if(statement2 != null){
                try {
                    statement2.close();}catch(SQLException e){
                    e.printStackTrace();}}
            dbUtil.close(statement, resultSet);}return false;}}
  • UserDao类 对数据库用户表的所有操作
package Other;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class UserDao {//根据用户名查找用户信息
    public static User findUser(String name){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        User user = null;
        try {
            String sql ="select * from user where name = ?";
            statement = dbUtil.preparedStatement(sql);
            statement.setString(1,name);
            resultSet = statement.executeQuery();if(resultSet.next()){
                boolean isAmin = resultSet.getInt("isAmin")==1;if(isAmin){
                    user = new Amin();}else{
                    user = new NormalUser();}
                user.setUserId(resultSet.getInt("userId"));
                user.setName(resultSet.getString("name"));
                user.setPassword(resultSet.getString("password"));
                user.setAmin(isAmin);}}catch(SQLException e){
            e.printStackTrace();}
        finally {
            dbUtil.close(statement,resultSet);}return user;}//新增普通用户
    public static boolean InsertNormal(User user){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        try {
            String sql ="insert into user values(null,?,?,0)";
            statement = dbUtil.preparedStatement(sql);
            statement.setString(1, user.getName());
            statement.setString(2, user.getPassword());int ret = statement.executeUpdate();return ret ==1;}catch(SQLException e){
            e.printStackTrace();} finally {
            dbUtil.close(statement, null);}return false;}//查看所有用户
    public staticvoidSelect(){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            String sql ="select * from user";
            statement = dbUtil.preparedStatement(sql);
            resultSet = statement.executeQuery();while(resultSet.next()){
                boolean ret = resultSet.getInt("isAmin")==1;
                User user = null;if(ret){
                    user = new Amin();
                    user.setAmin(ret);}else{
                    user = new NormalUser();
                    user.setAmin(ret);}
                user.setUserId(resultSet.getInt("userId"));
                user.setName(resultSet.getString("name"));

                System.out.println(user);}}catch(SQLException e){
            e.printStackTrace();} finally {
            dbUtil.close(statement, resultSet);}}//修改密码
    public static boolean UpdatePassword(String password,int userId){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        try {
            String sql ="Update user set password = ? where userId = ?";
            statement = dbUtil.preparedStatement(sql);
            statement.setString(1,password);
            statement.setInt(2,userId);int ret = statement.executeUpdate();if(ret ==1){
                System.out.println("修改成功！！！");return true;}else{
                System.out.println("修改失败！！！");return false;}}catch(SQLException e){
            e.printStackTrace();}
        finally {
            dbUtil.close(statement,null);}return false;}//删除用户
    public static boolean Delete(int userId){
        DBUtil dbUtil = new DBUtil();
        PreparedStatement statement = null;
        PreparedStatement statement2 = null;
        ResultSet resultSet = null;
        try {
            String str ="select * from user where userId = ?";
            statement = dbUtil.preparedStatement(str);
            statement.setInt(1,userId);
            resultSet = statement.executeQuery();if(!resultSet.next()){
                System.out.println("没有此用户");return false;}

            boolean ret = resultSet.getInt("isAmin")==1;if(ret){
                System.out.println("大胆，怎敢删管理员！！！");return false;}

            String sql ="delete from user where userId = ? ";
            statement2 = dbUtil.preparedStatement(sql);
            statement2.setInt(1, userId);
            statement2.executeUpdate();return true;}catch(SQLException e){
            e.printStackTrace();} finally {if(statement2 != null){
                try {
                    statement2.close();}catch(SQLException e){
                    e.printStackTrace();}}
            dbUtil.close(statement, resultSet);}return false;}}

实现业务

  • User类中添加 menu()抽象方法 NormalUser类中 重写menu() 和 work() Amin中重写 menu() 和 work()
  • 此处将work()变为work(int ret)，为了用户选择操作 work(int ret, int uesrId) 为了用户修改密码操作
  • Test类
import Op.InsetNormalOp;
import Op.Operation;
import Op.UpdatewordOp;
import Other.User;
import Other.UserDao;
import java.util.Scanner;

public class Test {
    public staticvoidmain(String[] args){
        Scanner scanner = new Scanner(System.in);
        System.out.println("---1.注册新用户  ---2.已有用户");int biu = scanner.nextInt();if(biu ==1){
            Operation op = new InsetNormalOp();
            op.operate();}

        System.out.println("请输入用户名");
        String name = scanner.next();
        System.out.println("请输入密码");
        String password = scanner.next();

        User user = UserDao.findUser(name);if(user == null){
            System.out.println("滚蛋！！！");
            System.exit(0);}if(!password.equals(user.getPassword())){
            System.out.println("滚蛋！！！");
            System.exit(0);}while(true){
            user.menu();
            System.out.println("请输入要进行的操作序号:");int ret = scanner.nextInt();

            user.work(ret,user.getUserId());}}}
  • User类
package Other;
import Op.Operation;

abstract public class User {
    private int userId;
    private String name;
    private String password;
    boolean isAmin;

    Operation[] operations = null;

    abstract public voidwork(int ret,int userId);

    abstract public voidmenu();

    public intgetUserId(){return userId;}

    public voidsetUserId(int userId){
        this.userId = userId;}

    public String getPassword(){return password;}

    public voidsetPassword(String password){
        this.password = password;}

    public String getName(){return name;}

    public voidsetName(String name){
        this.name = name;}

    public boolean isAmin(){return isAmin;}

    public voidsetAmin(boolean amin){
        isAmin = amin;}

    @Override
    public String toString(){return"User{"+"userId="+ userId +", name='"+ name +'\''+", isAmin="+ isAmin +'}';}}
  • NormalUser类
package Other;
import Op.*;

public class NormalUser extends User{//可进行的操作
    Operation[] operations ={
            new ExitOp(),
            new SelectOp(),
            new SelectByNameOp(),
            new BorrowOp(),
            new ReturnOp()};

    @Override
    public voidwork(int ret,int userId){if(ret ==5){
            UpdatewordOp.operate(userId);return;}if(ret <0|| ret >= operations.length){
            System.out.println("输入错误！！！");return;}
        operations[ret].operate();}

    @Override
    public voidmenu(){
        System.out.println("=================");
        System.out.println("  0.退出");
        System.out.println("  1.查看所有书籍 ");
        System.out.println("  2.根据书名查找书籍");
        System.out.println("  3.借书");
        System.out.println("  4.还书");
        System.out.println("  5.修改密码");
        System.out.println("=================");}}
  • Amin类
package Other;
import Op.*;

public class Amin extends User {//可进行的操作
    Operation[] operations ={
            new ExitOp(),
            new SelectOp(),
            new SelectByNameOp(),
            new InsertOp(),
            new DeleteOp(),
            new SelectUsersOp(),
            new SelectUsersByNameOp(),
            new DeleteUserOp()};
    @Override
    public voidwork(int ret,int userId){if(ret ==8){
            UpdatewordOp.operate(userId);return;}if(ret <0|| ret >= operations.length){
            System.out.println("输入错误！！！");return;}

        operations[ret].operate();}

    @Override
    public voidmenu(){
        System.out.println("=================");
        System.out.println("  0.退出");
        System.out.println("  1.查看所有书籍 ");
        System.out.println("  2.根据书名查找书籍");
        System.out.println("  3.新增书籍");
        System.out.println("  4.删除书籍");
        System.out.println("  5.查看所有用户");
        System.out.println("  6.根据名字查找用户");
        System.out.println("  7.删除用户");
        System.out.println("  8.修改密码");
        System.out.println("=================");}}

完善OP包中的各类操作

在这里插入图片描述

  • BorrowOp 借书
package Op;
import Other.BookDao;
import java.util.Scanner;

public class BorrowOp implements Operation{
    @Override
    public voidoperate(){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入所借图书的Id");int id = scanner.nextInt();
        Boolean ret = BookDao.Borrow(id);if(ret){
            System.out.println("借书成功！！！");}else{
            System.out.println("借书失败！！！");}}}
  • DeleteOp 删除书籍
package Op;
import Other.BookDao;
import java.util.Scanner;

public class DeleteOp implements Operation {
    @Override
    public voidoperate(){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入所要删除的图书的Id:");int id = scanner.nextInt();
        BookDao.Delete(id);}}
  • DeleteUserOp 删除用户
package Op;
import Other.UserDao;
import java.util.Scanner;

public class DeleteUserOp implements Operation{
    @Override
    public voidoperate(){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入删除的用户的Id:");int id = scanner.nextInt();
        boolean ret = UserDao.Delete(id);if(ret){
            System.out.println("删除成功！！！");}else{
            System.out.println("删除失败！！！");}}}
  • ExitOp 退出程序
package Op;

public class ExitOp implements Operation {
    @Override
    public voidoperate(){
        System.exit(0);}}
  • InsertOp 新增书籍
package Op;
import Other.Book;
import Other.BookDao;
import java.util.Scanner;

public class InsertOp implements Operation {
    @Override
    public voidoperate(){
        Book book = new Book();
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入新书的name:");
        book.setName(scanner.next());
        System.out.println("请输入新书的作者:");
        book.setAuthor(scanner.next());
        System.out.println("请输入新书的类型:");
        book.setType(scanner.next());
        Boolean ret = BookDao.Insert(book);if(ret){
            System.out.println("新增成功！！！");}else{
            System.out.println("新增失败！！！");}}}
  • InsetNormalOp 新增普通用户
package Op;
import Other.NormalUser;
import Other.User;
import Other.UserDao;
import java.util.Scanner;

public class InsetNormalOp implements Operation {
    @Override
    public voidoperate(){
        Scanner scanner = new Scanner(System.in);
        String name = null;while(true){
            System.out.println("用户名:");
            name = scanner.next();if(UserDao.findUser(name)== null){break;}
            System.out.println("该用户名已存在，请重新输入");}
        System.out.println("请输入密码:");
        User user = new NormalUser();
        user.setName(name);
        user.setPassword(scanner.next());
        boolean ret = UserDao.InsertNormal(user);if(ret){
            System.out.println("添加成功！！");}else{
            System.out.println("添加失败！！");}}}
  • ReturnOp 还书
package Op;
import Other.BookDao;
import java.util.Scanner;

public class ReturnOp implements Operation {
    @Override
    public voidoperate(){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入所还书的Id");int id = scanner.nextInt();
        Boolean ret = BookDao.Return(id);if(!ret){
            System.out.println("还书失败！！！");}}}
  • SelectByNameOp 根据书名查找图书
package Op;
import Other.BookDao;
import java.util.Scanner;

public class SelectByNameOp implements Operation {
    @Override
    public voidoperate(){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入书的名字:");
        String name = scanner.next();
        BookDao.SelectByName(name);}}
  • SelectOp 查看所有图书
package Op;
import Other.BookDao;

public class SelectOp implements Operation {
    @Override
    public voidoperate(){
        BookDao.Select();}}
  • SelectUsersByNameOp 根据用户名查找用户
package Op;
import Other.User;
import Other.UserDao;
import java.util.Scanner;

public class SelectUsersByNameOp implements Operation{
    @Override
    public voidoperate(){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入要查找的用户名:");
        String name = scanner.next();
        User user = UserDao.findUser(name);if(user == null){
            System.out.println("无此用户");}else{
            System.out.println(user);}}}
  • SelectUsersOp 查看所有用户
package Op;
import Other.User;
import Other.UserDao;
import java.util.Scanner;

public class SelectUsersOp implements Operation{
    @Override
    public voidoperate(){
        UserDao.Select();}}
  • UpdatewordOp 修改密码
package Op;
import Other.UserDao;
import java.util.Scanner;

public class UpdatewordOp{
    public staticvoidoperate(int userId){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入修改的密码:");
        String password1 = null;while(true){
            password1 = scanner.next();
            System.out.println("在输入一次:");
            String password2 = scanner.next();if(!password1.equals(password2)){
                System.out.println("两次不一致！！！");
                System.out.println("请重新输入");}else{break;}}
        UserDao.UpdatePassword(password1,userId);}}
标签： jdbc java 继承
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