前期效果

用户分为普通用户和管理员，登录进系统之后可以对图书进行一系列操作，此时我们要明白，对图书的操作是通过书架来执行的，我们平常在图书馆上借书就是在书架上

图书的创建

接下来我们来创建图书类，对图书的属性进行封装，并写上对应的get和set 方法，

    private String name;private String author;private int price;private String type;private boolean isBorrowed;public Book() {}public Book(String name, String author, int price, String type) {this.name = name;this.author = author;this.price = price;this.type = type;}/······get set toString······/

接下来就是创建书架的类，书架上肯定不止一本书，所以这里选择数组来存储多个book对象，因为在一开始就有了一部分书，所以在创建书架的对象时，就要把图书的对象放进去

public class BookList {private Book[] books = new Book[10];//用到了组合private int usedSize = 0;//实际放的数量public BookList() {//创建对象之后就已经有了三本书books[0] = new Book("三国演义", "罗贯中", 20,"小说");books[1] = new Book("西游记", "吴承恩", 30,"小说");books[2] = new Book("红楼梦", "曹雪芹", 20,"小说");usedSize = 3;}
}

用户的创建

接着创建用户，而用户又分为普通用户和管理员，就可以通过继承来实现这种关系，这两种用户的菜单也不相同，就可以抽取出来，在子类进行重写

public abstract class User {//不同包的子类可以访问protected String name;public User(String name) {this.name = name;}public abstract int menu();
}

之后就可以在Main类里面以多态的方式，根据不同的对象调取不同的菜单

public class Main {public static User login() {Scanner sc = new Scanner(System.in);System.out.println("请输入用户名：");String name = sc.nextLine();System.out.println("请输入身份：1.管理员 2. 普通用户");int choice = sc.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();}
}

操作的实现

菜单里的操作可以通过接口来实现这个业务逻辑，

public interface IOPeration {void work(BookList bookList);
}

例如添加图书，直接去实现一个操作接口，具体的逻辑再在本类中进行重写

public class AddOperation implements IOPeration{@Overridepublic void work(BookList bookList) {System.out.println("添加图书");}
}

接下来就是创建各种操作了

那么有了这些操作该怎么调用呢，无论时普通用户还是管理员，都是用户在操作，所以要在父类User中创建接口数组，再调用具体的方法实现操作


捋一下现在的逻辑

完善操作

接下来就是完善菜单中的操作内容了

显示图书

因为之前book是用数组存在BookList中的，所以只要遍历数组就可以了

BookList中要提供对应的get,set方法：

    public int getUsedSize() {return usedSize;}public Book getBook(int pos) {return books[pos];}public void setBook(int pos, Book book) {this.books[pos] = book;}

显示图书：

public class ShowOperation implements IOPeration{@Overridepublic void work(BookList bookList) {int currentSize = bookList.getUsedSize();for(int i= 0;i < currentSize;i++){System.out.println(bookList.getBook(i));//输出当前书架上的所有书籍信息}}
}

查找图书

明白了怎么遍历之后，查找图书就非常简单了

public class FindOperation implements IOPeration {@Overridepublic void work(BookList bookList) {System.out.println("请输入查找的图书：");Scanner sc = new Scanner(System.in);String name = sc.nextLine();int currentSize = bookList.getUsedSize();for(int i = 0;i < currentSize;i++){Book book = bookList.getBook(i);if(book.getName().equals(name)){System.out.println(book);return;}}System.out.println("不存在该图书");}
}

新增图书

public class AddOperation implements IOPeration {@Overridepublic void work(BookList bookList) {int currentSize = bookList.getUsedSize();if(currentSize == bookList.getBooks().length){System.out.println("书架已满，无法添加");return;}System.out.println("添加图书");System.out.println("请输入书名：");Scanner scanner = new Scanner(System.in);String name = scanner.nextLine();System.out.println("请输入作者：");String author = scanner.nextLine();System.out.println("请输入价格：");int price = scanner.nextInt();scanner.nextLine();System.out.println("请输入类型：");String type = scanner.nextLine();Book book = new Book(name, author, price, type);//添加图书bookList.setBook(currentSize, book);bookList.setUsedSize(currentSize + 1);System.out.println("添加成功");}
}

添加之后要记得更改currentSize

借阅图书

借书其实就是查找之后满足借阅条件就可以借阅

public class BorrowOperation implements IOPeration{public void work(BookList bookList) {System.out.println("请输入借阅的图书：");Scanner sc = new Scanner(System.in);String name = sc.nextLine();int currentSize = bookList.getUsedSize();for(int i = 0;i < currentSize;i++){Book book = bookList.getBook(i);if(book.getName().equals(name)){//判断是否借出if(book.isBorrowed()){System.out.println("该图书已被借阅");return;}//修改借阅状态book.setBorrowed(true);System.out.println("借阅成功");return;}}System.out.println("不存在该图书");}
}

归还图书

public class ReturnOperation implements IOPeration{@Overridepublic void work(BookList bookList) {System.out.println("请输入归还的图书：");Scanner sc = new Scanner(System.in);String name = sc.nextLine();int currentSize = bookList.getUsedSize();for (int i = 0; i < currentSize; i++) {Book book = bookList.getBook(i);if (book.getName().equals(name)) {//判断是否借出if (book.isBorrowed()) {//修改借阅状态book.setBorrowed(false);System.out.println("归还成功");return;}}}System.out.println("此书未被借出");}
}

删除图书

由于是用顺序表存储的图书，所以当删除其中的一本书之后，这本书后面的图书都要往前移

public class DeleteOperation implements IOPeration {@Overridepublic void work(BookList bookList) {System.out.println("请输入删除的图书：");Scanner sc = new Scanner(System.in);String name = sc.nextLine();int i = 0,pos = 0;int currentSize = bookList.getUsedSize();for(;i < currentSize;i++){Book book = bookList.getBook(i);if(book.getName().equals(name)){pos = i;break;}}if(i == currentSize){System.out.println("没有找到该图书");}for(int j = pos;j < currentSize - 1;j++){Book book = bookList.getBook(j + 1);bookList.setBook(j,book);}bookList.setBook(currentSize - 1,null);//更新currentSizebookList.setUsedSize(currentSize - 1);System.out.println("删除成功");}
}