javaSE之图书管理系统
思路：一个图书管理系统项目的构建
本次的代码是实现一个图书管理系统要求，有登入系统和用户选择系统，之后还有用户操作交换系统，和图书管理系统，具体思路如下
创建以下类，加粗部分为包
test：Test
book：Book Bookshlef
opertion：IOpeation (接口）ExitOpeartion ShowOpeartion FindOpeartion DelOperation AddOpeartion BorrowOpeartion
user：AdminUser NormalUser
接下来我们先实现登陆和用户选择系统
public class Test { public static User back(){ Scanner sc = new Scanner(System.in); System.out.println("请输入你的名字"); String username = sc.nextLine(); System.out.println("请输入你的身份 1.普通用户 2.管理员"); int result = sc.nextInt(); if(result == 1){ return new NormalUser(username); } else if(result == 2){ return new AdminUser(username); } else return null; }public static void main(){ //这里用了多态中的向上转型，从而调用了子类重写父类的方法，用User数据类型接受User 方法，创建user对象 User user = back(); int choice = user.meau(); }接下来我们来写用户包
public class AdminUser exdents User{ @Override public int menu() { Scanner sc = new Scanner(System.in); System.out.println("欢迎登陆，"+this.name+"."); System.out.println("*********************"); System.out.println("1.查找图书"); System.out.println("2.新增图书"); System.out.println("3.减少图书"); System.out.println("4,显示图书"); System.out.println("0,推出系统"); System.out.println("***********************"); System.out.println("请输入你的操作。。。。。"); int choice =sc.nextInt(); return choice; } }public class NormalUser extends User{ @Override public int menu() { Scanner sc = new Scanner(System.in); System.out.println("欢迎登陆，"+this.name+"."); System.out.println("*********************"); 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,推出系统"); System.out.println("***********************"); System.out.println("请输入你的操作。。。。。"); int choice =sc.nextInt(); return choice; } }public abstract class User{ protected String name; //这种对象数组用来存要选择的操作类对象 public IOPeration[] ioperation; public User(String name) { this.name = name; } //抽象方法子类重写 abstract public int menu(); }Book包
public class Book { private String title; private String author; private int price; private String type; private boolean isborrowed; public boolean isIsborrowed() { return isborrowed; } public void setIsborrowed(boolean isborrowed) { this.isborrowed = isborrowed; } public Book(String title, String author, int price, String type) { this.title = title; this.author = author; this.price = price; this.type = type; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } 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; } @Override //重写toString方法方便观察 public String toString() { return "Book{" + "title='" + title + '\'' + ", author='" + author + '\'' + ", price=" + price + ", type='" + type + '\'' + //判断是否借出 ( (isborrowed == true) ? " 已借出" : " 未借出") +"}"; } }public class Bookshelf{ private Book[] book = new Book[10]; private int usersize; //构造方法通过创建对象来赋初始值 public Bookshelf(){ this.book[0] =new Book("三国杀","狗卡",6480,"卡牌"); this.book[1] =new Book("原神","大伟哥",648,"开放世界"); this.book[2] =new Book("三角洲行动","张姐",10,"fps"); this.book[3] =new Book("鸣潮","松轮",10,"开放世界"); this.usersize=4; } public int getUsersize() { return usersize; } public void setUsersize(int usersize) { this.usersize = usersize; } //重写getbook方法和setbook方法，其中pos为数组的下标 public Book getBook(int pos){ return book[pos]; } public Book[] getBook() { return book; } public void setBook(int pos, Book book) { this.book[pos] = book; } }接着是操作方法和接口
接口
public interface IOPeration { void work(Bookshelf bookshelf); }每一个操作方法都要接上接口确保代码的一致性
查找书籍
public class FindOperation implements IOPeration{ @Override public void work(Bookshelf bookshelf) { System.out.println("查找图书。。。"); Scanner sc = new Scanner(System.in); System.out.println("请输入你要找的书的书名字"); String name = sc.nextLine(); int size =bookshelf.getUsersize(); //遍历数组 for(int i=0;i<size;i++){ //调用getbook方法将值赋予book对象 Book book =bookshelf.getBook()[i]; //使用Object类的equals方法比较名字 if(book.getTitle().equals(name)){ System.out.println("找到了这本书"); System.out.println(book); return; } } System.out.println("没有你要找的这本书"); } }退出系统
public class ExitOperation implements IOPeration{ public void work(Bookshelf bookshelf){ System.out.println("退出系统"); //0为编译器最终停止的标志 System.exit(0); } }借出书籍
public class BorrowOperation implements IOPeration{ @Override public void work(Bookshelf bookshelf){ System.out.println("借阅图书。。。"); Scanner sc = new Scanner(System.in); System.out.println("请输入你要找的书的书名字"); String name = sc.nextLine(); int size =bookshelf.getUsersize(); for(int i=0;i<size;i++){ Book book =bookshelf.getBook()[i]; if(book.getTitle().equals(name)){ //调用了isIsborrowed方法，但Isborrowed返回值是布尔类型,默认值为false if(book.isIsborrowed()){ System.out.println("这本书已经被借出了"); return; } book.setIsborrowed(true); System.out.println("借阅成功"); return; } } System.out.println("没有你要找的这本书"); } }归还书籍
public class ReturnOperation implements IOPeration{ @Override public void work(Bookshelf bookshelf) { System.out.println("归还图书"); Scanner sc = new Scanner(System.in); System.out.println("请输入你要归还的图书的名字"); String name = sc.nextLine(); int size = bookshelf.getUsersize(); for(int i=0;i<size;i++){ Book book = bookshelf.getBook()[i]; if(book.getTitle().equals(name)){ if(book.isIsborrowed()) { book.setIsborrowed(false); System.out.println("归还成功"); return; } } } System.out.println("没有你要归还的图书"); } }显示图书
public class ShowOperation implements IOPeration{ @Override public void work(Bookshelf bookshelf) { System.out.println("显示图书"); int size=bookshelf.getUsersize(); for (int i=0;i<size;i++) { Book book=bookshelf.getBook(i); System.out.println(book); } } }增加图书
public class JoinOperation implements IOPeration{ public void work(Bookshelf bookshelf) { System.out.println("增加图书。。。"); Scanner sc = new Scanner(System.in); int size = bookshelf.getUsersize(); //判断有没有插满 if (size == bookshelf.getBook().length) { System.out.println("书架满了"); return; } System.out.println("请输入标题"); String name = sc.nextLine(); System.out.println("请输入作者"); String author = sc.nextLine(); System.out.println("请输入类型"); String type = sc.nextLine(); System.out.println("请输入价格"); int price = sc.nextInt(); Book newbook = new Book(name,author,price,type); //判断有没有这本书 int i=0; for(;i<size;i++){ Book book =bookshelf.getBook()[i]; if(book.getTitle().equals(name)){ System.out.println("有这本书"); System.out.println(book); return; } } //插入这本书 bookshelf.setBook(i,newbook); bookshelf.setUsersize(bookshelf.getUsersize() + 1); System.out.println("添加成功"); } }减少图书
public class DelectOperation implements IOPeration{ @Override public void work(Bookshelf bookshelf) { System.out.println("减少图书"); Scanner sc = new Scanner(System.in); int size = bookshelf.getUsersize(); System.out.println("请选择你要删除书的名字"); String name = sc.nextLine(); //找书的下标 int pos =999; int i=0; for(;i<size;i++) { Book book = bookshelf.getBook(i); if (book.getTitle().equals(name)) { pos = i; break; } } if(i==size){ System.out.println("没有找到你要删除的书"); return; } //删除书的操作 for (int j=pos;j<size;j++) { Book book = bookshelf.getBook(j); book = bookshelf.getBook(j+1); bookshelf.setBook(j,book); } bookshelf.setUsersize(bookshelf.getUsersize() - 1); System.out.println("删除成功"); } }这里有些超纲说一下思路：找到要删除的下标的图书，用之后的一个下标的图书覆盖掉这个图书，以此类推，之后下一个下标再被下下个下标给覆盖，注意j<size，不然可能会造成
数组越界异常
接下来我们就要给用户类添加一个构造方法用来选择代码具体如下
管理员类
public class AdminUser extends User { public AdminUser(String name){ super(name); //引用父类对象数组创建对象，利用下标来实现选择 this.ioperation = new IOPeration[] { new ExitOperation(), new FindOperation(), new JoinOperation(), new DelectOperation(), new ShowOperation() }; } @Override public int menu() { Scanner sc = new Scanner(System.in); System.out.println("欢迎登陆，"+this.name+"."); System.out.println("*********************"); System.out.println("1.查找图书"); System.out.println("2.新增图书"); System.out.println("3.减少图书"); System.out.println("4,显示图书"); System.out.println("0,推出系统"); System.out.println("***********************"); System.out.println("请输入你的操作。。。。。"); int choice =sc.nextInt(); return choice; } }用户类
public class NormalUser extends User { public NormalUser(String name) { super(name); //引用父类对象数组创建对象，利用下标来实现选择 this.ioperation = new IOPeration[] { new ExitOperation(), new FindOperation(), new BorrowOperation(), new ReturnOperation(), }; } @Override public int menu() { Scanner sc = new Scanner(System.in); System.out.println("欢迎登陆，"+this.name+"."); System.out.println("*********************"); 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,推出系统"); System.out.println("***********************"); System.out.println("请输入你的操作。。。。。"); int choice =sc.nextInt(); return choice; } }User父类
public abstract class User implements IOPeration{ protected String name; //这种对象数组用来存要选择的操作类对象 public IOPeration[] ioperation; public User(String name) { this.name = name; } //抽象方法子类重写 abstract public int menu(); //重写接口方法 @Override public void work(Bookshelf bookshelf) { } //重载接口方法，引用操作类的work方法 public void work(int choice, Bookshelf bookshelf) { ioperation[choice].work(bookshelf); } }这下我们来写Test类
public static void main() { Bookshelf bookshelf = new Bookshelf(); //创建use对象 User user = back(); while(true){ //choice来接受要选择的操作 int choice = user.menu(); user.work(choice,bookshelf); } }这样写的话是不是代码架构特别清晰，这样也方便维护和接入新的操作方法和其他如用户账户密码的系统，有兴趣的话读者可以自己尝试增加新的系统，如果要存储数据的话还可以使用mysql语言来编写数据库存储数据，或者用io流存储到服务器，当然这些都是后话
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