前言
前几篇文章讲到了Java的基本语法规则，今天我们就用前面学到的数组，类和对象，封装，继承，多态，抽象类，接口等做一个图书管理借阅系统。
🥇1.分析图书管理系统要实现的功能
Java语言是面向对象的，所以首先要分析完成这个图书管理系统，有哪些对象：
👱使用者User
📘书Book
📲操作Operation
使用者分为两种，普通用户（NormalUser）和图书管理员（AdminUser）对于普通用户来说，需要查找，借阅，归还图书操作。
对于图书管理员来说，需要查找，新增，删除，显示图书操作。
🥇2.在IDEA中创建对象
🥇3.实现book对象
🥉Book类
书有以下属性：
书名 String name
作者 String author
价格 int price
类型 String type
是否被借出 boolean isBorrow
private String name;
private String author;
private int price;
private String type;
private boolean isBorrowed;
注意：这里的控制符全部设置为了私有的，需要提供方法来获取
提供get( )和set( )进行设置和获取
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;
}
提供一个构造方法
注意构造方法中不提供isBorrow，isBorrow是boolean类型，默认值为false，表示未被借出
public Book(String name, String author, int price, String type) {
this.name = name;
this.author = author;
this.price = price;
this.type = type;
}
提供ToString方法显示书的信息
public String toString() {
return "Book{" +
"name='" + name + '\'' +
", author='" + author + '\'' +
", price=" + price +
", type='" + type + '\'' +
", isBorrowed=" + isBorrowed +((isBorrowed==true)?"已被借阅":"未被借阅")+
'}';
}
完整的book类
package book;
public class Book {
private String name;
private String author;
private int price;
private String type;
private boolean isBorrowed;
//构造方法
public Book(String name, String author, int 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 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{" +
"name='" + name + '\'' +
", author='" + author + '\'' +
", price=" + price +
", type='" + type + '\'' +
", isBorrowed=" + isBorrowed +((isBorrowed==true)?"已被借阅":"未被借阅")+
'}';
}
}
🥉BookList类
用于存放book，相当于书架
设置一个book类型的数组存放书
private Book[] books;
再设置一个成员变量记录书的数量
private int usedSize;
提供一个构造方法，进行一次初始化
public BookList() {
this.books =new Book[DEFAULT_CAPACITY];
//初始化三本书
this.books[0]=new Book("三国演义","罗贯中",10,"小说");
this.books[1]=new Book("西游记","吴承恩",10,"小说");
this.books[2]=new Book("红楼梦","曹雪芹",10,"小说");
this.usedSize=3;
}
再提供一个book类型的成员方法获取下标为pos的book
public Book getBook(int pos) {
return books[pos];
}
再提供一个方法，给一个数组下标和book，存放到bookList中
public void setBooks(int pos,Book book) {
books[pos]=book;
}
提供一个方法，获取书的数量
public int getUsedSize() {
return usedSize;
}
提供一个方法，修改书的数量
public void setUsedSize(int usedSize) {
this.usedSize = usedSize;
}
提供一个方法，获取book数组
public Book[] getBooks() {
return books;
}
完整的BookList类
package book;
public class BookList {
private Book[] books;
private int usedSize;
private static final int DEFAULT_CAPACITY = 10;
public BookList() {
this.books =new Book[DEFAULT_CAPACITY];
//初始化三本书
this.books[0]=new Book("三国演义","罗贯中",10,"小说");
this.books[1]=new Book("西游记","吴承恩",10,"小说");
this.books[2]=new Book("红楼梦","曹雪芹",10,"小说");
this.usedSize=3;
}
public Book getBook(int pos) {
return books[pos];
}
public void setBooks(int pos,Book book) {
books[pos]=book;
}
public int getUsedSize() {
return usedSize;
}
public void setUsedSize(int usedSize) {
this.usedSize = usedSize;
}
public Book[] getBooks() {
return books;
}
}
🥇4.功能
管理员或是普通用户，对书的操作都是在BookList类的数组books中进行操作，提供一个IOperation的接口，实现对数组的操作
public interface IOperation {
void work(BookList bookList);
}
创建各种类，来实现对书的所有操作，引用IOperation接口，对方法进行重写
举个例子：
public class AddOperation implements IOperation {
@Override
public void work(BookList bookList) {
System.out.println("新增图书!");
}
}
🥇5.面向用户
普通用户和图书管理员都是用户，需要进行操作，所以我们直接创建一个User类
package user;
import book.BookList;
import operation.IOperation;
public abstract class User {
protected String name;
protected IOperation[] iOperation;
public User(String name) {
this.name = name;
}
public abstract int menu();
public void doOperation(int choice, BookList bookList) {
iOperation[choice].work(bookList);
}
}
🥉普通用户类
package user;
import operation.*;
import java.util.Scanner;
public class NormalUser extends User{
public NormalUser(String name) {
super(name);
this.iOperation=new IOperation[]{
new ExitOperation(),
new FindOperation(),
new BorrowOperation(),
new ReturnOperation()
};
}
@Override
public int menu() {
System.out.println("**********普通用户******");
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);
System.out.println("请输入你的操作：");
int choice=scanner.nextInt();
return choice;
}
}
🥉图书管理员
package user;
import operation.*;
import java.util.Scanner;
public class AdminUser extends User{
public AdminUser(String name) {
super(name);
this.iOperation=new IOperation[]{
new ExitOperation(),
new FindOperation(),
new AddOperation(),
new DelOperation(),
new ShowOperation(),
};
}
@Override
public int menu() {
System.out.println("**********管理员用户*****");
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);
System.out.println("请输入你的操作：");
int choice=scanner.nextInt();
return choice;
}
}
🥉测试类
将所有类连接起来，使类之间相互交互
package user;
import book.BookList;
import java.util.Scanner;
import operation.*;
public class Main {
public static User login(){
System.out.println("请输入你的名字： ");
Scanner scanner=new Scanner(System.in);
String name= scanner.nextLine();
System.out.println("请输入你的身份：1.管理员 2.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();
while(true){
int choice= user.menu();
System.out.println("choice: "+choice);
user.doOperation(choice,bookList);
}
}
}
运行结果
文章来源：https://www.toymoban.com/news/detail-633867.html
🥇5.实现操作功能
🥉新增图书
package operation;
import book.Book;
import book.BookList;
import java.util.Scanner;
public class AddOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("新增图书！");
Scanner scanner = new Scanner(System.in);
System.out.println("请输入名字：");
String name = scanner.nextLine();
System.out.println("请输入作者：");
String author = scanner.nextLine();
System.out.println("请输入类型：");
String type = scanner.nextLine();
System.out.println("请输入价格：");
int price = scanner.nextInt();
Book book=new Book(name,author,price,type);
int curr=bookList.getUsedSize();
for (int i = 0; i < curr; i++) {
Book book1=bookList.getBook(i);
if(book1.getName().equals(name)){
System.out.println("该书已存在，无法存放！");
} else if (curr==bookList.getBooks().length) {
System.out.println("已经存放满，无法再存放！");
}else {
bookList.setBooks(curr,book);
bookList.setUsedSize(curr+1);
}
}
}
}
🥉删除图书
package operation;
import book.Book;
import book.BookList;
import java.util.Scanner;
public class DelOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("删除图书！");
Scanner scanner = new Scanner(System.in);
System.out.println("请输入你要删除的书名：");
String name=scanner.nextLine();
int curr= bookList.getUsedSize();
int pos=-1;
for (int i = 0; i < curr; i++) {
Book book1=bookList.getBook(i);
if(book1.getName().equals(name)) {
pos = i;
break;
}
}
if (pos==-1){
System.out.println("没有找到书名！");
}else {
int j=pos;
for ( ; j < curr-1; j++) {
Book book=bookList.getBook(j+1);
bookList.setBooks(j,book);
}
bookList.setBooks(j,null);
bookList.setUsedSize(curr-1);
System.out.println("删除成功！");
}
}
}
🥉查找图书
package operation;
import book.Book;
import book.BookList;
import java.util.Scanner;
public class FindOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("查找图书！");
Scanner scanner = new Scanner(System.in);
System.out.println("请输入你要查找的书名：");
String name=scanner.nextLine();
int curr= bookList.getUsedSize();
for (int i = 0; i < curr; i++) {
Book book=bookList.getBook(i);
if(book.getName().equals(name)){
System.out.println("找到你想查找的书名：");
System.out.println(book);
return;
}
}
System.out.println("你要查找的书籍不存在");
}
}
🥉借阅图书
package operation;
import book.Book;
import book.BookList;
import java.util.Scanner;
public class BorrowOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("借阅图书！");
Scanner scanner=new Scanner(System.in);
System.out.println("请输入你要借阅的书名：");
String name=scanner.nextLine();
int curr=bookList.getUsedSize();
for (int i = 0; i < curr; i++) {
Book book = bookList.getBook(i);
if(book.getName().equals(name)){
book.setBorrowed(true);
System.out.println("借阅成功！");
System.out.println(book);
return;
}
}
System.out.println("借阅的书籍不存在！");
}
}
🥉归还图书
package operation;
import book.Book;
import book.BookList;
import java.util.Scanner;
public class ReturnOperation implements IOperation {
@Override
public void work(BookList bookList) {
System.out.println("归还图书！");
Scanner scanner = new Scanner(System.in);
System.out.println("请输入你要归还的书名：");
String name= scanner.nextLine();
int curr= bookList.getUsedSize();
for (int i = 0; i < curr; i++) {
Book book=bookList.getBook(i);
if(book.getName().equals(name)){
book.setBorrowed(false);
System.out.println("归还成功！");
System.out.println(book);
return;
}
}
System.out.println("未查找到你要归还的书名！");
}
}
🥉打印图书
package operation;
import book.BookList;
public class ShowOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("打印图书！");
int curr= bookList.getUsedSize();
for (int i = 0; i < curr; i++) {
System.out.println(bookList.getBook(i));
}
}
}
🥉退出系统
package operation;
import book.BookList;
public class ExitOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("退出图书！");
System.out.println("退出系统！");
System.exit(0);
}
}
写文至此，如有不同见解或者疑惑，欢迎在评论区留言！文章来源地址https://www.toymoban.com/news/detail-633867.html
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