前言:
图书馆管理系统需要结合JavaSE的绝大部分知识,是一个很好的训练项目。
为了让大家更加方便的查阅与学习,我把代码放开头,供大家查询。
还有对代码的分析,我将以类为单位分开讲解。
目录
全部代码
java
/*一共有三个包*/
//User包
//User.java
package user;
import Book.BookList;
import Operation.IOparetion;
public abstract class User {
protected String name;
protected IOparetion[] iOparetions;
public User(String name) {
this.name = name;
}
public abstract int menu();
public void doIOparetion(int chioce, BookList bookList){
this.iOparetions[chioce].work(bookList);
}
}
//User包
//NormalUser.java
package user;
import Operation.*;
import java.util.Scanner;
public class NormalUser extends User{
public NormalUser(String name) {
super(name);
this.iOparetions= new IOparetion[] {
new ExitOparetion(),
new FindOparetion(),
new BorrowedOparetion(),
new ReturnOparetion()
};
}
@Override
public int menu() {
System.out.println("******管理员用户******");
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("******************");
System.out.println("请输入数字:");
Scanner scanner=new Scanner(System.in);
int choice= scanner.nextInt();
return choice;
}
}
//User包
//Administrators.java
package user;
import Operation.*;
import java.util.Scanner;
public class Administrators extends User {
public Administrators(String name) {
super(name);
this.iOparetions = new IOparetion[]{
new ExitOparetion(),
new FindOparetion(),
new AddOparetion(),
new DelOparetion(),
new ShowOparetion()
};
}
public int menu() {
System.out.println("******普通用户******");
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("******************");
System.out.println("请输入数字:");
Scanner scanner = new Scanner(System.in);
int choice = scanner.nextInt();
return choice;
}
}
//Book包
//Book.java
package Book;
public class Book {
private String name;
private String author;
private int price;
private String type;
private boolean isLend;
public Book(String name, String author, int price, String type) {
this.name = name;
this.author = author;
this.price = price;
this.type = type;
}
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 isLend() {
return isLend;
}
public void setLend(boolean lend) {
isLend = lend;
}
@Override
public String toString() {
return "Book{" +
"name='" + name + '\'' +
", author='" + author + '\'' +
", price=" + price +
", type='" + type + '\'' +
(isLend==true?"已借出":"未借出")+
'}';
}
}
//Book包
//BookList.java
package Book;
public class BookList {
private Book[] book=new Book[10];
private int usedSize;
public Book getBook(int pos) {
return book[pos];
}
public void setBook(int pos,Book book) {
this.book[pos] = book;
}
public int getUsedSize() {
return usedSize;
}
public void setUsedSize(int usedSize) {
this.usedSize = usedSize;
}
public BookList() {
book[0]=new Book("西游记","吴承恩",19,"小说");
book[1]=new Book("三国演义","罗贯中",36,"小说");
book[2]=new Book("红楼梦","曹雪芹",13,"小说");
this.usedSize=3;
}
public boolean isFull(){
if(usedSize==book.length){
return true;
}return false;
}
}
//Oparetion包
//Ioparetion.java
package Operation;
import Book.BookList;
public interface IOparetion {
void work(BookList bookList);
}
//Oparetion包
//AddOparetion.java
package Operation;
import Book.Book;
import Book.BookList;
import java.util.Scanner;
public class AddOparetion implements IOparetion {
@Override
public void work(BookList bookList) {
Scanner scanner=new Scanner(System.in);
System.out.println("请输入你要添加的书籍名字");
String name=scanner.nextLine();
System.out.println("请输入作者的名字");
String author=scanner.nextLine();
System.out.println("请输入书的种类");
String type=scanner.nextLine();
System.out.println("请输入书的价格");
int price=scanner.nextInt();
Book book=new Book(name,author,price,type);
if(bookList.isFull()){
System.out.println("书架满了,借阅失败");
return;
}
bookList.setBook(bookList.getUsedSize(), book);
bookList.setUsedSize(bookList.getUsedSize()+1);
System.out.println("添加成功");
}
}
//Oparetion包
//BorrowedOparetion.java
package Operation;
import Book.BookList;
import java.util.Scanner;
public class BorrowedOparetion implements IOparetion{
@Override
public void work(BookList bookList) {
System.out.println("请输入你要找的书名");
Scanner scanner=new Scanner(System.in);
String name=scanner.nextLine();
for(int i=0;i<bookList.getUsedSize();i++){
if(name.equals(bookList.getBook(i).getName())){
bookList.getBook(i).setLend(true);
System.out.println("借阅成功");
return;
}
}
System.out.println("借阅失败");
}
}
//Oparetion包
//DelOparetion.java
package Operation;
import Book.BookList;
import java.util.Scanner;
public class DelOparetion implements IOparetion{
@Override
public void work(BookList bookList) {
System.out.println("请输入你要删除的书籍名字");
Scanner scanner=new Scanner(System.in);
String s=scanner.nextLine();
int pos=-1;
int i=0;
for (;i<bookList.getUsedSize();i++){
if(s.equals(bookList.getBook(i))){
pos=i;
}
if(i>=bookList.getUsedSize()){
System.out.println("没有你要找的书");
return;
}
}for(int j=i;i<bookList.getUsedSize()-1;i++){
bookList.setBook(j,bookList.getBook(j+1));
}
bookList.setBook(bookList.getUsedSize(), null);
bookList.setUsedSize(bookList.getUsedSize()-1);
System.out.println("删除成功");
}
}
//Oparetion包
//ExitOparetion.java
package Operation;
import Book.BookList;
public class ExitOparetion implements IOparetion {
@Override
public void work(BookList bookList) {
System.out.println("退出系统中....");
for(int i=0;i<bookList.getUsedSize()-1;i++){
bookList.setBook(i,null);
}
System.exit(0);
}
}
//Oparetion包
//FindOparetion.java
package Operation;
import Book.BookList;
import java.util.Scanner;
public class FindOparetion implements IOparetion{
@Override
public void work(BookList bookList) {
System.out.println("请输入你要找的书名");
Scanner scanner=new Scanner(System.in);
String name=scanner.nextLine();
for(int i=0;i<bookList.getUsedSize();i++){
if(name.equals(bookList.getBook(i).getName())){
System.out.println("找到了,下标为:"+i);
System.out.println(bookList.getBook(i));
return;
}
}
System.out.println("没找到");
}
}
//Oparetion包
//ReturnOparetion.java
package Operation;
import Book.BookList;
import java.util.Scanner;
public class ReturnOparetion implements IOparetion{
@Override
public void work(BookList bookList) {
Scanner scanner=new Scanner(System.in);
System.out.println("请输入你要归还的书名");
String s=scanner.nextLine();
for (int i = 0; i < bookList.getUsedSize()-1; i++) {
if(s.equals(bookList.getBook(i).getName())){
bookList.getBook(i).setLend(false);
System.out.println("归还成功");
return;
}
}
System.out.println("归还失败,没有你要归还的书");
}
}
//Oparetion包
//ShowOparetion.java
package Operation;
import Book.BookList;
public class ShowOparetion implements IOparetion{
@Override
public void work(BookList bookList) {
for(int i=0;i<bookList.getUsedSize();i++){
System.out.println(bookList.getBook(i));
}
}
}
首先,我们需要打个框架出来,由于java是一门面向对象的编程,所以我们应该要多考虑对象,而不是过程。
我将它分为三个包:User、Book、operation包 ,其实对象有:书架、书、用户、管理员。
总体请看下图:
这里我主要讲解大致结构和细微的细节 ,因为方法的思路在数据结构讲解更加清晰
Main类
java
public class Main {
public static User login(){
Scanner scanner=new Scanner(System.in);
System.out.println("请输入你的名字");
String name=scanner.nextLine();
System.out.println("请输入你的身份:1.普通用户 2.管理员用户");
int choice =scanner.nextInt();
if(choice==1){
NormalUser normalUser=new NormalUser(name);
return normalUser;
}else{
Administrators administrators=new Administrators(name);
return administrators;
}
}
public static void main(String[] args) {
BookList bookList=new BookList();
User user=login();
while (true){
int ret=user.menu();
user.doIOparetion(ret,bookList);
}
}
}
上述代码中:
Scanner来new一个对象来输入,int一个choice来接收选1还是2,选择是管理人还是普通用户。
由于要返回一个对象,所以login的返回值是user类型的,user与管理员和普通用户是父子关系,在main中用user类型接收,属于向上转型(好处就是发生多态)。
User类
java
package user;
import Book.BookList;
import Operation.IOparetion;
public abstract class User {
protected String name;
protected IOparetion[] iOparetions;
public User(String name) {
this.name = name;
}
public abstract int menu();
public void doIOparetion(int chioce, BookList bookList){
this.iOparetions[chioce].work(bookList);
}
}
上述代码中:
User作为父类,被管理员和普通用户继承,被abstract修饰主要是为了menu这个方法被继承,实现多态。
IOparetion是一个接口,是为了被那些add和del等等方法实现的,还是实现多态,
它现在作为一个数组来接收,是为了存放这些方法 ,这样就不用一个个在用户或者管理员里面书写了,可以直接定义为一个类(这也是为什么方法可以另外书写的原因),这体现了面向对象的特点,大大缩短了工程量和分模块的简洁性(即使下次有人需要用,不需要再写,直接调用就好了)。
BookList类
java
package Book;
public class BookList {
private Book[] book=new Book[10];
private int usedSize;
public Book getBook(int pos) {
return book[pos];
}
public void setBook(int pos,Book book) {
this.book[pos] = book;
}
public int getUsedSize() {
return usedSize;
}
public void setUsedSize(int usedSize) {
this.usedSize = usedSize;
}
public BookList() {
book[0]=new Book("西游记","吴承恩",19,"小说");
book[1]=new Book("三国演义","罗贯中",36,"小说");
book[2]=new Book("红楼梦","曹雪芹",13,"小说");
this.usedSize=3;
}
public boolean isFull(){
if(usedSize==book.length){
return true;
}return false;
}
}
对于上述代码:
由于java是面向对象编程,所以对于一些信息不需要用户来知道内部是怎么实现的 ,所以用private修饰,这样的话需要set和get方法来获取,这样之后的代码都需要调用set和get来获取或者是赋值。
BookList是书架,所以里面是摆书的,所以用Book类型作为数组,来收取book。可以放很多本。
usedsize是有效书籍数,就是记录里面有多少本。
Book类
java
package Book;
public class Book {
private String name;
private String author;
private int price;
private String type;
private boolean isLend;
public Book(String name, String author, int price, String type) {
this.name = name;
this.author = author;
this.price = price;
this.type = type;
}
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 isLend() {
return isLend;
}
public void setLend(boolean lend) {
isLend = lend;
}
@Override
public String toString() {
return "Book{" +
"name='" + name + '\'' +
", author='" + author + '\'' +
", price=" + price +
", type='" + type + '\'' +
(isLend==true?"已借出":"未借出")+
'}';
}
}
对于上述代码:
Book是类,它代表的是一本书,所以你需要定义名字作者价格什么什么的。
也是利用封装,只把必要的信息给用户,所以用privat密封起来,更加安全一点,所以需要set和get方法。
这里的toString方法里面有个三目操作符,如果isLend被借出的话,就是true,就会打印已借出,否则为借出。
NormalUser类
java
package user;
import Operation.*;
import java.util.Scanner;
public class NormalUser extends User{
public NormalUser(String name) {
super(name);
this.iOparetions= new IOparetion[] {
new ExitOparetion(),
new FindOparetion(),
new BorrowedOparetion(),
new ReturnOparetion()
};
}
@Override
public int menu() {
System.out.println("******管理员用户******");
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("******************");
System.out.println("请输入数字:");
Scanner scanner=new Scanner(System.in);
int choice= scanner.nextInt();
return choice;
}
}
对于上述代码:
如果继承了父类,使用构造方法时候需要先把父类的构造方法实现。
因为IOparetion是user里面的,user被普通用户继承,所以可以直接访问,把他变成一个数组,这样就可以存方法了,不用在这普通用户这个类里一个一个方法写,直接脱离出来,非常充分体现了面向对象的特点!