编写图书馆管理系统
思路
要编写这个程序我们首相要清楚这个程序中有哪些对象,不考虑复杂情况，基本的对象有三个：
- 书
- 用户
那么我们就分别讨论这三个对象有哪些属性和有哪些动作。
- 书籍 它会有书名，编号(id)， 作者， 类别， 价格， 是否被借 这些简单的属性
- 用户包括：管理员和普通用户，管理员它会有姓名， 增加书籍， 删除书籍， 查找书籍， 打印所有书籍信息， 退出系统 这些简单属性。
普通用户它会有姓名， 查找书籍， 借阅书籍， 归还书籍， 退出系统这些简单的属性。
我们把这三个对象分别放入三个包中，这样在分别完成这些对象中所需的动作(方法)。
我们书籍包中的代码：
package book;
public class Book {
private String name;
private String id;
private String author;
private String type;
private int price;
private boolean isBorrow;
public Book(String name, String id, String author, String type, int price, boolean isBorrow) {
this.name = name;
this.id = id;
this.author = author;
this.type = type;
this.price = price;
this.isBorrow = isBorrow;
}
public String getId() {
return id;
}
public boolean isBorrow() {
return isBorrow;
}
public void setBorrow(boolean borrow) {
isBorrow = borrow;
}
public String getName() {
return name;
}
@Override
public String toString() {
return "Book{" +
"name='" + name + '\'' +
", id='" + id + '\'' +
", author='" + author + '\'' +
", type='" + type + '\'' +
", price=" + price +
", isBorrow=" + isBorrow +
'}';
}
}
同时创建一个类似顺序表的书籍数组保存书籍。
package book;
public class BookList {
private Book[] books = new Book[100];
private int size;
public BookList() {
books[0] = new Book("金瓶梅",
"001", "兰陵笑笑生","古典名著",
100, false);
books[1] = new Book("水浒传",
"002", "施耐庵","古典名著",
100, false);
books[2] = new Book("西游记",
"003", "吴承恩","古典名著",
100, false);
size = 3;
}
public int getSize() {
return size;
}
public void setSize(int size) {
this.size = size;
}
public Book getBook(int index) {
return books[index];
}
public void setBooks(int index, Book book) {
books[index] = book;
}
}
我们将用所有的操作方法放入operation包中，所有的方法都用接口来实现，这样我们就避免了使用一大堆的 if else
接口：
package operation;
import book.BookList;
public interface IOperation {
void work(BookList bookList);
}
增加新书籍：
package operation;
import book.Book;
import book.BookList;
import java.util.Scanner;
public class AddBookOperation implements IOperation{
@Override
public void work(BookList bookList) {
System.out.println("新增一本书籍!");
System.out.println("请输入新增书籍的书名: ");
Scanner scanner = new Scanner(System.in);
String name = scanner.next();
System.out.println("请输入新增书籍的id: ");
String id = scanner.next();
System.out.println("请输入新增书籍的作者: ");
String author = scanner.next();
System.out.println("请输入新增书籍的类型: ");
String type = scanner.next();
System.out.println("请输入新增书籍的价格: ");
int price = scanner.nextInt();
Book book = new Book(name, id, author, type, price, false);
bookList.setBooks(bookList.getSize(), book);
bookList.setSize(bookList.getSize() + 1);
}
}
删除书籍：
package operation;
import book.Book;
import book.BookList;
import java.util.Scanner;
public class DeleteBookOperation implements IOperation {
@Override
public void work(BookList bookList) {
System.out.println("删除书籍!");
System.out.println("请输入您想要删除书籍的id: ");
Scanner scanner = new Scanner(System.in);
String id = scanner.next();
int i = 0;
for (; i < bookList.getSize(); i++) {
Book book = bookList.getBook(i);
if (book.getId().equals(id)) {
break;
}
}
if (i >= bookList.getSize()) {
System.out.println("未找到要找的书籍!");
return;
}
Book lastBook = bookList.getBook(bookList.getSize() - 1);
bookList.setBooks(i, lastBook);
bookList.setSize(bookList.getSize() - 1);
System.out.println("删除成功!");
}
}
查找书籍：
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("查找书籍!");
System.out.println("请输入要查找书籍的书名: ");
Scanner scanner = new Scanner(System.in);
String name = scanner.next();
int count = 0;
for (int i = 0; i < bookList.getSize(); i++) {
Book book = bookList.getBook(i);
if (book.getName().equals(name)) {
System.out.println(book);
count++;
}
}
if (count == 0) {
System.out.println("没找到此书籍!");
} else {
System.out.println("共找到 " + count + " 本相同书籍!");
}
}
}
借阅书籍：
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("借阅书籍!");
System.out.println("请输入要借阅的书籍的id: ");
Scanner scanner = new Scanner(System.in);
String id = scanner.next();
for (int i = 0; i < bookList.getSize(); i++) {
Book book = bookList.getBook(i);
if (!book.getId().equals(id)) {
continue;
}
if (book.isBorrow()) {
System.out.println("此书已经被借走了!");
break;
}
book.setBorrow(true);
System.out.println("借阅成功");
}
}
}
归还书籍：
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("归还书籍!");
System.out.println("请输入要归还书籍的id: ");
Scanner scanner = new Scanner(System.in);
String id = scanner.next();
int i = 0;
for ( ; i < bookList.getSize(); i++) {
Book book = bookList.getBook(i);
if (!book.getId().equals(id)) {
continue;
}
if (!book.isBorrow()) {
System.out.println("这本书未借出去,归还失败!");
}
book.setBorrow(false);
}
}
}
打印所有书籍信息：
package operation;
import book.BookList;
public class PrintAllOperation implements IOperation {
@Override
public void work(BookList bookList) {
for (int i = 0; i < bookList.getSize(); i++) {
System.out.println(bookList.getBook(i));
}
System.out.println("共有 " + bookList.getSize() + " 本书籍");
}
}
退出系统：
package operation;
import book.BookList;
public class ExitOperation implements IOperation {
@Override
public void work(BookList bookList) {
System.out.println("GoodBye!");
System.exit(0);
}
}
我们用户中先创建一个抽象的用户，再将不同用户通过实现这个抽象的用户来实现不同用户的操作权限。
我们用户包中的代码
抽象的用户代码：
package user;
import book.BookList;
import operation.IOperation;
abstract public class User {
protected String name;
protected IOperation[] operations;
public User(String name) {
this.name = name;
}
abstract public int menu();
public void doOperation(int choice, BookList bookList) {
operations[choice].work(bookList);
}
}
管理员用户：
package user;
import book.BookList;
import operation.*;
import java.util.Scanner;
public class Admin extends User{
public Admin(String name) {
super(name);
operations = new IOperation[] {
new ExitOperation(),
new AddBookOperation(),
new DeleteBookOperation(),
new FindOperation(),
new PrintAllOperation(),
};
}
@Override
public int menu() {
System.out.println("============");
System.out.println("hello " + name);
System.out.println("1. 增加书籍");
System.out.println("2. 删除书籍");
System.out.println("3. 查找书籍");
System.out.println("4. 打印所有信息");
System.out.println("0. 退出");
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;
}
}
普通用户：
package user;
import operation.*;
import java.util.Scanner;
public class NormalUser extends User {
public NormalUser(String name) {
super(name);
operations = new IOperation[] {
new ExitOperation(),
new FindOperation(),
new BorrowOperation(),
new ReturnOperation(),
};
}
@Override
public int menu() {
System.out.println("============");
System.out.println("hello " + name);
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");
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;
}
}
这样就完成了一个简单的图书馆管理系统。
