目录
4.1在user包里面先创建一个User 类，这是一个抽象类
1.知识结合
知识点：类，抽象类，封装，继承，多态，接口等。
熟悉类与类之间的关系
掌握抽象类，接口，继承，封装等知识点的应用
下图为用到的包和类
2.系统使用效果
2.1管理员系统
查找图书
新增图书和显示图书
2.2普通用户使用系统
查找图书
借阅图书的归还图书
3.图书存储类
1.创建一个book包，用来表示存储书的文件
在book包里创建Book类，作为一本书
package book;
public class Book {
private String name;//书名
private String author;//作者
private double price;//价格
private String type;//类型
private boolean isBorrowed;//是否借出
public Book(String name, String author, double price, String type) {
this.name = name;
this.author = author;
this.price = price;
this.type = type;
}
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 double getPrice() {
return price;
}
public void setPrice(double 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{" +
"name='" + name + '\'' +
", author='" + author + '\'' +
", price=" + price +
", type='" + type + '\'' +
((isBorrowed == true) ? " 已经被借出 " : " 未被借出 ")+
'}';
}
}
在book包里创建BookList 类，用来存储书
package book;
public class BookList {
private Book[] books = new Book[10];
private int usedSize;
public BookList() {
books[0] = new Book("平凡的世界","路遥",34.0,"小说");
books[1] = new Book("百万英镑","马克.吐温",20.0,"小说");
books[2] = new Book("追风筝的人","胡塞尼",30.0,"小说");
this.usedSize = 3;
}
public int getUsedSize() {
return usedSize;
}
public void setUsedSize(int usedSize) {
this.usedSize = usedSize;
}
/**
* 获取到pos 位置的一本书
* @param pos
* @return
*/
public Book getPos(int pos) {
return this.books[pos];
}
/**
* 设置下标为一本书
* @param pos
* @param book
*/
public void setBooks(int pos,Book book) {
this.books[pos] = book;
}
}
4.创建用户相关的类
创建一个user包
4.1在user包里面先创建一个User 类，这是一个抽象类
package user;
import book.BookList;
import operation.IOperation;
public abstract class User {
protected String name;
protected IOperation[] iOperations;
public User(String name) {
this.name = name;
}
public abstract int menu();
public void doWork(int choice, BookList bookList) {
iOperations[choice].work(bookList);
}
}4.2创建管理员类 AdmiUser，是User 的子类
package user;
import operation.*;
import java.util.Scanner;
public class AdminUser extends User{
public AdminUser(String name) {
super(name);
this.iOperations = new IOperation[] {
new ExitOperation(),
new FindOperation(),
new AddOperation(),
new DelOperation(),
new DisplayOperation(),
};
}
public int menu() {
System.out.println("-----------------管理员菜单-----------------");
System.out.println("hello "+ this.name +" 欢迎来到图书管理系统");
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("------------------------------------------");
Scanner scanner = new Scanner(System.in);
int choice = scanner.nextInt();
return choice;
}
}
4.3创建普通用户使用类 NormalUser ,是User 的子类
package user;
import operation.*;
import java.util.Scanner;
public class NormalUser extends User{
public NormalUser(String name) {
super(name);
this.iOperations = new IOperation[] {
new ExitOperation(),
new FindOperation(),
new BorrowOperation(),
new ReturnOperation(),
};
}
public int menu() {
System.out.println("-----------------普通用户菜单-----------------");
System.out.println("hello "+ this.name +" 欢迎来到图书使用系统");
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("------------------------------------------");
Scanner scanner = new Scanner(System.in);
int choice = scanner.nextInt();
return choice;
}
}5.创建操作相关的类
先创建一个operation包，然后在包里面创建操作类
5.1各个类的接口 IOperation
package operation;
import book.BookList;
import java.util.Scanner;
public interface IOperation {
Scanner scanner = new Scanner(System.in);
void work(BookList bookList);
}5.2新增图书类AddOperation
package operation;
import book.Book;
import book.BookList;
public class AddOperation implements IOperation{
public void work(BookList bookList) {
System.out.println("新增图书！");
System.out.println("请输入图书的名字： ");
String name = scanner.nextLine();
System.out.println("请输入图书的作者：");
String author = scanner.nextLine();
System.out.println("请输入图书的类型：");
String type = scanner.nextLine();
System.out.println("请输入图书的价格：");
double price = scanner.nextDouble();
Book book = new Book(name,author,price,type);
int size = bookList.getUsedSize();
bookList.setBooks(size,book);
bookList.setUsedSize(size+1);
System.out.println("新增图书成功");
}
}5.3借阅图书类BorrowOperation
package operation;
import book.Book;
import book.BookList;
public class BorrowOperation implements IOperation{
public 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：");
String name = scanner.nextLine();
int size = bookList.getUsedSize();
for (int i = 0; i < size; i++) {
Book book = bookList.getPos(i);
if (name.equals(book.getName())) {
book.setBorrowed(true);
System.out.println("借阅成功");
System.out.println(book);
return;
}
}
System.out.println("查无此书，请重新查找");
}
}5.4删除图书类DelOperation
package operation;
import book.Book;
import book.BookList;
public class DelOperation implements IOperation{
public void work(BookList bookList) {
System.out.println("删除图书！");
//根据书名找到书的位置 index
System.out.println("请输入你要删除的图书名");
String name = scanner.nextLine();
int currentSize = bookList.getUsedSize();
int index = 0;//存储找到的下标
int i = 0;
for (;i < currentSize; i++) {
Book book = bookList.getPos(i);
if (book.getName().equals(name)) {
index = i;
break;
}
}
if (i >= currentSize) {
System.out.println("没有你要删除的书");
return;
}
//2.进行删除
for (int j = index; j < currentSize - 1; j++) {
Book book = bookList.getPos(j+1);
bookList.setBooks(j,book);//把书往前移一步
}
bookList.setBooks(currentSize,null);
bookList.setUsedSize(currentSize-1);
System.out.println("删除成功！");
}
}
5.5打印图书类DisplayOperation
package operation;
import book.Book;
import book.BookList;
public class DisplayOperation implements IOperation{
public void work(BookList bookList) {
System.out.println("打印图书！");
int size = bookList.getUsedSize();
for (int i = 0; i < size; i++) {
Book book = bookList.getPos(i);
System.out.println(book);
}
}
}5.6查找图书类FindOperation
package operation;
import book.Book;
import book.BookList;
import com.sun.media.jfxmediaimpl.HostUtils;
public class FindOperation implements IOperation{
public void work(BookList bookList) {
System.out.println("查找图书！");
System.out.println("请输入你要查找的书名");
String name = scanner.nextLine();
int size = bookList.getUsedSize();
for (int i = 0; i < size; i++) {
Book book = bookList.getPos(i);
if (book.getName().equals(name)) {
System.out.println("找到的书信息如下");
System.out.println(book);
return;
}
}
System.out.println("查无此书");
}
}5.7归还图书类ReturnOperation
package operation;
import book.Book;
import book.BookList;
public class ReturnOperation implements IOperation{
public 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：");
String name = scanner.nextLine();
int size = bookList.getUsedSize();
for (int i = 0; i < size; i++) {
Book book = bookList.getPos(i);
if (name.equals(book.getName())) {
book.setBorrowed(false);
System.out.println("归还成功！");
System.out.println(book);
return;
}
}
System.out.println("你要归还的图书不属于改系统");
}
}
5.8退出系统类ExitOperation
package operation;
import book.BookList;
public class ExitOperation implements IOperation{
public void work(BookList bookList) {
System.out.println("退出系统！");
System.exit(0);
}
}
6.Main 类和main 方法
import book.BookList;
import user.AdminUser;
import user.NormalUser;
import user.User;
import java.util.Scanner;
/**
* 整个程序的入口
*/
public class Main {
public static User login() {
System.out.println("请输入你的姓名");
Scanner scanner = new Scanner(System.in);
String name = 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(name);
}else {
return new NormalUser(name);
}
}
public static void main(String[] args) {
BookList bookList = new BookList();
User user = login();//向上转型
while (true) {
int choice = user.menu();//发生了动态绑定--多态
user.doWork(choice,bookList);
}
}
}