运行环境:IDEA
1、实现根据不同身份登陆;
2、用户身份:管理员、普通用户
管理员实现功能
:增加图书、删除图书、查看所有书籍的列表、查阅某个书籍的信息、退出程序;
普通用户
:借阅书籍、归还书籍、查阅某个书籍的信息、退出程序。
我们找到这个系统的一个个的对象,逐步来实现。
图书管理系统,首先最重要的就是书。
在创建类里面的属性时,明确封装是面向对象的重要核心之一,设计这个 book 类的时候,book 类的属性,尽可能封装起来,用 private,使其他的程序猿能不用理解具体细节,降低使用成本。
package Test1_28_LibraryManagementSystem;
public class Book {
private String name;
private String author;
private double price;
private String type;
// 默认是false ,但是显示的写出来可读性更好
private boolean isBorrowed = false;
// 每本书的名字、价格、作者、类型,可能不同
// 使用构造方法,构造的时候以传入参数的形式,确定具体的值
// 构造实例时,显示的创建相关参数,来传入相关信息
public Book(String name, String author, double price, String type) {
this.name = name;
this.author = author;
this.price = price;
this.type = type;
}
// 重写 toString 方法才能在打印书籍信息时,以字符串的样子打印出来
@Override
public String toString() {
return "Book{" +
"name='" + name + '\'' +
", author='" + author + '\'' +
", price=" + price +
", type='" + type + '\'' +
", isBorrowed=" + isBorrowed +
'}';
}
// getter / setter 和封装是相悖的 ,但是封装并不是百分百藏起来,完全包裹起来调用者不好使用。
public String getName() {
return name;
}
public boolean isBorrowed() {
return isBorrowed;
}
public void setBorrowed(boolean borrowed) {
isBorrowed = borrowed;
}
}
为了记录所有书籍信息,创建一个书籍列表
package Test1_28_LibraryManagementSystem;
public class BookList {
Book books[] = new Book[100];
int size = 0;
// 这样就写死了这些书,创建实例它们就存在
public BookList() {
books[0] = new Book("西游记","吴承恩",50.0,"古典名著");
books[1] = new Book("水浒传","施耐庵",50.0,"古典名著");
books[2] = new Book("三国演义","罗贯中",50.0,"古典名著");
books[3] = new Book("红楼梦","曹雪芹",50.0,"古典名著");
size = 4;
}
// 通过 getter和setter 来获取和修改书籍列表
public Book getBook(int index) {
return books[index];
}
public void setBook(int index,Book book) {
books[index] = book;
}
public int getSize() {
return size;
}
public void setSize(int size) {
this.size = size;
}
}
1、管理员
package Test1_28_LibraryManagementSystem;
import Test1_28_LibraryManagementSystem.IOperation.*;
import java.util.Scanner;
public class Admin extends User{
public Admin(String name) {
this.name = name;
this.operations = new IOperation[]{
new AddOperation(),
new DelOperation(),
new DisplayBookList(),
new FindOperation(),
new ExitOperation()
};
}
@Override
public int menu() {
System.out.println("*********************");
System.out.println(" 1、新增书籍 ");
System.out.println(" 2、删除书籍 ");
System.out.println(" 3、展示书籍列表 ");
System.out.println(" 4、查找某本书籍 ");
System.out.println(" 5、退出系统 ");
System.out.println("*********************");
System.out.println("请输入您的选择:");
Scanner scanner = new Scanner(System.in);
int choice = scanner.nextInt();
return choice;
}
}
2、普通用户
package Test1_28_LibraryManagementSystem;
import Test1_28_LibraryManagementSystem.IOperation.*;
import java.util.Scanner;
public class NormalUser extends User{
public NormalUser(String name) {
this.name = name;
this.operations = new IOperation[]{
new BorrowOperation(),
new ReturnOperation(),
new FindOperation(),
new ExitOperation()
};
}
public int menu(){
System.out.println("*********************");
System.out.println(" 1、借阅书籍 ");
System.out.println(" 2、归还书籍 ");
System.out.println(" 3、查找某本书籍 ");
System.out.println(" 4、退出系统 ");
System.out.println("*********************");
System.out.println("请输入您的选择:");
Scanner scanner = new Scanner(System.in);
int choice = scanner.nextInt();
return choice;
}
}
3、用户
创建抽象类 User ,这样在使用时,调用者可以不关注是管理员还是普通用户,管理员和用户继承 User 。
package Test1_28_LibraryManagementSystem;
import Test1_28_LibraryManagementSystem.IOperation.IOperation;
abstract public class User {
protected String name;
protected IOperation[] operations;
public abstract int menu();
public void doOperation(int choice,BookList bookList){
this.operations[choice - 1].work(bookList);
}
}
设计用户操作,每种类都可以设置成一个类,每个操作类中都有一个 work 方法,public 修饰、返回void、传入BookList。因为他们有共性,就可以把共性信息提取出来,做成一个接口。(消除重复 并且 在不相关的类之间建立联系)
当前 IOperation 这个接口其实就是把所有的用户操作给统一规范起来了,什么样的类作为一种用户的操作?只要实现了这个接口,就可以作为用户的操作。
1、接口
package Test1_28_LibraryManagementSystem.IOperation;
import Test1_28_LibraryManagementSystem.BookList;
public interface IOperation {
void work(BookList bookList);
}
注意:
如果多各类之间,公共的部分只有方法的话,此时使用接口;
如果多个类之间,公共的部分不光有方法还有属性,此时使用继承(普通父类 / 抽象父类)。
1、新增书籍
package Test1_28_LibraryManagementSystem.IOperation;
import Test1_28_LibraryManagementSystem.Book;
import Test1_28_LibraryManagementSystem.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("请输入要新增书籍的书名:");
String name = scanner.next();
System.out.println("请输入书籍作者的名字:");
String author = scanner.next();
System.out.println("请输入书籍的价格:");
Double price = scanner.nextDouble();
System.out.println("请输入书籍的类型:");
String type = scanner.next();
Book newBook = new Book(name,author,price,type);
bookList.setBook(bookList.getSize(),newBook);
bookList.setSize(bookList.getSize() + 1);
}
}
2、删除书籍
package Test1_28_LibraryManagementSystem.IOperation;
import Test1_28_LibraryManagementSystem.BookList;
import java.util.Scanner;
import java.util.jar.JarOutputStream;
public class DelOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("删除书籍 >> ");
Scanner scanner = new Scanner(System.in);
System.out.println("请输入要删除书籍的书名:");
String name = scanner.next();
int i = 0;
for (; i < bookList.getSize(); i++) {
if(name.equals(bookList.getBook(i).getName())) {
if(i == bookList.getSize() - 1) {
bookList.setSize(bookList.getSize() - 1);
System.out.println("删除成功");
return;
}
bookList.setBook(i,bookList.getBook(bookList.getSize() - 1));
bookList.setSize(bookList.getSize() - 1);
System.out.println("删除成功");
return;
}
}
if (i >= bookList.getSize() - 1) {
System.out.println("未找到《" + name + "》,删除失败");
}
}
}
3、展示书籍列表
package Test1_28_LibraryManagementSystem.IOperation;
import Test1_28_LibraryManagementSystem.BookList;
public class DisplayBookList implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("展示书籍列表 >> ");
for (int i = 0; i < bookList.getSize(); i++) {
System.out.println(bookList.getBook(i));
}
}
}
4、查找某本书籍信息
package Test1_28_LibraryManagementSystem.IOperation;
import Test1_28_LibraryManagementSystem.BookList;
import java.util.Scanner;
public class FindOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("查找某本书籍信息 >> ");
Scanner scanner = new Scanner(System.in);
System.out.println("请输入要查找书籍的书名:");
String name = scanner.next();
int i = 0;
for (; i < bookList.getSize(); i++) {
if(bookList.getBook(i).getName().contains(name)) {
System.out.println(bookList.getBook(i));
System.out.println("查找成功");
return;
}
}
if(i >= bookList.getSize() - 1) {
System.out.println("未找到《" + name + "》,查找失败");
}
}
}
5、退出系统
package Test1_28_LibraryManagementSystem.IOperation;
import Test1_28_LibraryManagementSystem.BookList;
public class ExitOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("退出系统 >> ");
System.exit(0);
}
}
1、借阅书籍
package Test1_28_LibraryManagementSystem.IOperation;
import Test1_28_LibraryManagementSystem.BookList;
import java.util.Scanner;
public class BorrowOperation implements IOperation {
@Override
public void work(BookList bookList) {
System.out.println("借阅书籍 >> ");
Scanner scanner = new Scanner(System.in);
System.out.println("请输入要借阅书籍的书名:");
String name = scanner.next();
int i = 0;
for (; i < bookList.getSize(); i++) {
if(name.equals(bookList.getBook(i).getName())) {
if(!bookList.getBook(i).isBorrowed()) {
bookList.getBook(i).setBorrowed(true);
System.out.println("借阅成功");
return;
}
System.out.println("《" + name + "》已被借阅,借阅失败");
return;
}
}
if(i >= bookList.getSize() - 1) {
System.out.println("未找到 《" + name + "》,借阅失败");
}
}
}
2、归还书籍
package Test1_28_LibraryManagementSystem.IOperation;
import Test1_28_LibraryManagementSystem.BookList;
import java.util.Scanner;
public class ReturnOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("归还书籍 >> ");
Scanner scanner = new Scanner(System.in);
System.out.println("请输入要归还书籍的书名:");
String name = scanner.next();
for (int i = 0; i < bookList.getSize(); i++) {
if(name.equals(bookList.getBook(i).getName())) {
if(!bookList.getBook(i).isBorrowed()) {
System.out.println("《" + name + "》未被借阅,归还失败");
return;
}
bookList.getBook(i).setBorrowed(false);
System.out.println("归还成功");
return;
}
}
System.out.println("未找到《" + name + "》,归还失败");
}
}
3、查找某本书的信息( 与管理员的查找相同 )
package Test1_28_LibraryManagementSystem.IOperation;
import Test1_28_LibraryManagementSystem.BookList;
import java.util.Scanner;
public class FindOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("查找某本书籍信息 >> ");
Scanner scanner = new Scanner(System.in);
System.out.println("请输入要查找书籍的书名:");
String name = scanner.next();
int i = 0;
for (; i < bookList.getSize(); i++) {
if(bookList.getBook(i).getName().contains(name)) {
System.out.println(bookList.getBook(i));
System.out.println("查找成功");
return;
}
}
if(i >= bookList.getSize() - 1) {
System.out.println("未找到《" + name + "》,查找失败");
}
}
}
4、退出系统( 与管理员的查找相同 )
package Test1_28_LibraryManagementSystem.IOperation;
import Test1_28_LibraryManagementSystem.BookList;
public class ExitOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("退出系统 >> ");
System.exit(0);
}
}
package Test1_28_LibraryManagementSystem;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
BookList bookList = new BookList();
// 向上转型,login返回管理员或普通用户
User user = login();
while (true) {
//多态
int choice = user.menu();
user.doOperation(choice,bookList);
}
}
private static User login() {
Scanner scanner = new Scanner(System.in);
System.out.println("请输入您的姓名:");
String name = scanner.next();
System.out.println(name + "欢迎使用!");
System.out.println("请选择您的身份:");
System.out.println(" 0、管理员 1、用户 ");
int who = scanner.nextInt();
if(who == 0){
return new Admin(name);
}
return new NormalUser(name);
}
}