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