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代码仓库地址：Java图书管理系统

1.前言

该项目将JavaSE的封装继承多态三大特性，使用了大量面向对象的操作，有利于巩固理解

（1）实现效果

2.实现步骤

第一步先把框架搭建起来，即创建出人：管理员和普通用户，书：书架

再实现内部的业务逻辑

（1）书book包下类的实现

此时我们先实现图书中的成员属性

1.Book类的实现

此时我们实现了图书所对应的成员变量，以及所对应的构造方法来初始化，Getter和Setter方法。toString方法。

注意：构造方法中不需要初始化布尔类型的islend，因为它默认是false未借出的状态
因为成员变量都是private修饰的，只能在当前类下访问，所以我们使用Getter和Setter使得它在其它类的实现下可以访问（即后期新增图书设置书名，作者等时）
重写toString方法是为了能够正确显示数据所对应的成员变量，而不是地址

package book;public class Book {private String name;private String author;private int price;private String type;private boolean islend;//是否被借出，默认为false未借出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 isIslend() {return islend;}public void setIslend(boolean islend) {this.islend = islend;}public Book(String name, String author, int price, String type) {this.name = name;this.author = author;this.price = price;this.type = type;}@Overridepublic String toString() {return "Book{" +"name='" + name + '\'' +", author='" + author + '\'' +", price=" + price +", type='" + type + '\'' +", islend=" + islend +'}';}
}

2.BookList类的实现

usedSigned用来记录当前存放了多少书

private Book[] books = new Book[10];是指书架上能放十本书

当将BookList中初始化为三本书时，要将usedSized置为3

package book;public class BookList {private Book[] books = new Book[10];private int usedSized;public BookList() {books[0]=new Book("三国演义","罗贯中",89,"小说");books[1]=new Book("西游记","吴承恩",78,"小说");books[2]=new Book("红楼梦","曹雪芹",49,"小说");this.usedSized=3;}
}

（2）用户user包下类的实现

1.User类的实现

package user;public class User {protected String name;public User(String name) {this.name = name;}
}

2.AdminUser类的实现

package user;public class AdminUser extends User{public AdminUser(String name) {super(name);}public void menu() {System.out.println("*******管理员菜单******");}
}

3.NormalUser类的实现

package user;public class NormalUser extends User{public NormalUser(String name) {super(name);}public void menu() {System.out.println("*******普通用户菜单******");}
}

以上代码Main函数的实现情况

AdminUser和NormalUser在login类中的返回值应返回User，因为它俩都继承了User
需要增加User类下的menu()方法，并将该类和该方法设为抽象类，不描述对象只用于继承以便当user调用不同用户下的菜单发生动态绑定

引用AdminUser和 NormalUser发生向上转型体现在不同用户下都存在的menu()方法

User user = login();此时发生动态绑定，有可能引用管理员用户，也有可能引用普通用户

user.menu();  //user调用的对象不一样，调用同一个方法会发生动态绑定

Main类

import user.AdminUser;
import user.NormalUser;
import user.User;import java.util.Scanner;public class Main {public static User login() {System.out.println("请输入姓名:");Scanner scanner = new Scanner(System.in);String userName = scanner.nextLine();System.out.println("请输入你的身份: 1-》管理员  0-》普通用户");int choice = scanner.nextInt();if (choice == 1) {return new AdminUser(userName);} else {return new NormalUser(userName);}//引用AdminUser和 NormalUser发生向上转型体现在不同用户下都存在的menu()方法}public static void main(String[] args) {//此时发生动态绑定，有可能引用管理员用户，也有可能引用普通用户User user = login();user.menu();  //user调用的对象不一样，调用同一个方法会发生动态绑定}
}

实现

完善不同用户下的menu菜单

1.管理员用户下的menu

 @Overridepublic int menu() {System.out.println("*******管理员菜单******");System.out.println("1. 查找图书");System.out.println("2. 新增图书");System.out.println("3. 删除图书");System.out.println("4. 显示图书");System.out.println("0. 退出系统");System.out.println("请输入你的操作: ");Scanner scanner=new Scanner(System.in);int choice=scanner.nextInt();return choice;}

1.普通用户下的menu

@Overridepublic int menu() {System.out.println("*******普通用户菜单******");System.out.println("1. 查找图书");System.out.println("2. 借阅图书");System.out.println("3. 归还图书");System.out.println("0. 退出系统");System.out.println("请输入你的操作: ");Scanner scanner=new Scanner(System.in);int choice=scanner.nextInt();return choice;}

重写menu设置了int类型的返回值，所以要修改User下抽象类menu的返回值

此时不同用户下调用menu菜单返回的choice是一个整型值，我们定义一个变量来接收这个值，以便后续当返回choice调用不同用户下所对应的功能

（3）接口及不同用户下不同操作的实现

//IOperation接口
package operation;import book.BookList;public interface IOperation {public void work(BookList bookList);
}//AddOperation类
package operation;import book.BookList;public class AddOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("新增图书......");}
}//BorrowedOperation类
package operation;import book.BookList;public class BorrowedOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("借阅图书......");}
}//DelOperation类
package operation;import book.BookList;public class DelOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("删除图书......");}
}//ExitOperation类
package operation;import book.BookList;public class ExitOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("退出系统......");}
}//FindOperation类
package operation;import book.BookList;public class FindOperation implements IOperation {@Overridepublic void work(BookList bookList) {System.out.println("查找图书......");}
}//ReturnOperation类
package operation;import book.BookList;public class ReturnOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("归还图书......");}
}//ShowOperation类
package operation;import book.BookList;public class ShowOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("展示图书......");}
}

为了区分哪些是管理员的操作哪些是普通用户的操作，我们使用接口的方法来组织这些对象
并在User类下定义一个调用接口的数组，protected IOperation[] iOperations;（不能定义在对应的用户下面，因为不同的用户会继承User类，这样就不用重复定义）
因为AdminUser和NormalUser继承了User类所以它俩都继承了User类下定义的数组
不同用户下对应的操作不一样，所以当我们继承User类中定义的数组时，在不同的用户下进行不同的初始化

5.对应的下标要相对应

6.当User发生动态绑定引用管理员用户或者普通用户时会返回choice，我们又在不同用户下初始化了ioperation数组，那我们怎样操作当输入choice时调用相应用户所对应的类进而再发生动态绑定输出对应的类

(4)具体业务的实现

1.FindOperation

package operation;import book.Book;
import book.BookList;import java.util.Scanner;public class FindOperation implements IOperation {@Overridepublic void work(BookList bookList) {System.out.println("查找图书......");System.out.println("请输入你要查找的图书名：");Scanner scanner = new Scanner(System.in);String bookName = scanner.nextLine();int CurrentSize = bookList.getUsedSized();for (int i = 0; i < CurrentSize; i++) {Book book = bookList.getBook(i);if(book.getName().equals(bookName)) {System.out.println("找到了这本书：");System.out.println(book);return;}}System.out.println("没有你要找的书");}
}

2.ShowOperation

package operation;import book.Book;
import book.BookList;public class ShowOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("展示图书......");int CurrentSize = bookList.getUsedSized();for (int i = 0; i < CurrentSize; i++) {Book book = bookList.getBook(i);System.out.println(book);}}
}

3.AddOperation

package operation;import book.Book;
import book.BookList;import java.util.Scanner;public class AddOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("新增图书......");if(bookList.isFull()) {System.out.println("书架满了，不能新增了");return;}Scanner scanner = new Scanner(System.in);System.out.println("请输入你要新增图书的书名：");String name = scanner.nextLine();System.out.println("请输入你要新增图书的作者：");String author = scanner.nextLine();System.out.println("请输入你要新增图书的类型：");String type = scanner.nextLine();System.out.println("请输入你要新增图书的价格：");int price = scanner.nextInt();Book book = new Book(name,author,price,type);int currentSize = bookList.getUsedSized();//把书放到指定的位置bookList.setBook(currentSize,book);//修改usedSizebookList.setUsedSized(currentSize+1);System.out.println("新增图书成功");/*for (int i = 0; i < currentSize; i++) {Book temp = bookList.getBook(i);if(temp.getName().equals(name)) {System.out.println("已经存在，不能增加！");return;}}*/}
}

4.DelOperation

删除图书和添加图书类似

package operation;import book.Book;
import book.BookList;import java.util.Scanner;public class DelOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("删除图书......");System.out.println("请输入你要删除的图书名：");Scanner scanner = new Scanner(System.in);String bookName = scanner.nextLine();int CurrentSize = bookList.getUsedSized();int pos = -1;int i = 0;for (i = 0; i < CurrentSize; i++) {Book book = bookList.getBook(i);if(book.getName().equals(bookName)) {pos = i;break;}}if (i >= CurrentSize) {System.out.println("没有你要删除的图书");return;}//开始删除for (int j = pos; j < CurrentSize-1; j++) {//bookList[j] = bookList[j+1]Book book = bookList.getBook(j+1);bookList.setBook(j,book);}bookList.setUsedSized(CurrentSize-1);bookList.setBook(CurrentSize-1,null);System.out.println("删除成功");}
}

5.ExitOperation

package operation;import book.BookList;public class ExitOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("退出系统......");int CurrentSize = bookList.getUsedSized();for (int i = 0; i < CurrentSize; i++) {bookList.setBook(i,null);}System.exit(0);}}

6.BorrowedOperation

只需找到该图书后改变它是否被借出的状态即可

package operation;import book.Book;
import book.BookList;import java.util.Scanner;public class BorrowedOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("借阅图书......");System.out.println("请输入你要借阅的图书名：");Scanner scanner = new Scanner(System.in);String bookName = scanner.nextLine();int CurrentSize = bookList.getUsedSized();int pos = -1;int i = 0;for (i = 0; i < CurrentSize; i++) {Book book = bookList.getBook(i);if(book.getName().equals(bookName)) {book.setIslend(true);System.out.println("借阅成功");return;}}System.out.println("借阅失败");}
}

7.ReturnOperation

同借书改变状态即可

package operation;import book.Book;
import book.BookList;import java.util.Scanner;public class ReturnOperation implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("归还图书......");System.out.println("请输入你要归还的图书名：");Scanner scanner = new Scanner(System.in);String bookName = scanner.nextLine();int CurrentSize = bookList.getUsedSized();int pos = -1;int i = 0;for (i = 0; i < CurrentSize; i++) {Book book = bookList.getBook(i);if(book.getName().equals(bookName)) {book.setIslend(false);System.out.println("归还成功");return;}}System.out.println("归还失败");}
}