教科书级代码分层思想

下面代码主要是写了一个小型的图书馆管理系统。基本功能就是增删改查。
系统虽然小，但是分层，综合应用上有很强的实际意义，作为菜鸟的我，应当好好研究下，从中吸取经验。
  1 import java.util.List;
  2 import java.util.ArrayList;
  3 import java.util.Scanner;
  4 import java.util.Iterator;
  5 
  6 /*
  7     1. 编号
  8     2. 书名
  9     3. 借出状态
 10 */
 11 class Book {
 12     
 13     private int id ;
 14     private String name ;
 15     private String flag ;
 16     
 17     public void setId(int id){
 18         this.id = id ;
 19     }
 20     public int getId(){
 21         return this.id;
 22     }
 23     
 24     public void setName(String name){
 25         this.name = name ;
 26     }
 27     public String getName(){
 28         return this.name;
 29     }
 30     
 31     public void setFlag(String flag){
 32         this.flag = flag ;
 33     }
 34     public String getFlag(){
 35         return this.flag;
 36     }
 37 }
 38 
 39 class Manager{
 40     private List<Book> list ;
 41     
 42     final static int maxCount = 100;
 43     
 44     public List<Book> getList(){
 45         return initList();
 46     }
 47     
 48     private List<Book> initList() {
 49         
 50         this.list = new ArrayList<Book>();
 51         Book book1 = new Book();
 52         book1.setId(1);
 53         book1.setName("水浒传");
 54         book1.setFlag("可借");
 55         
 56         list.add(book1);
 57         
 58         Book book2 = new Book();
 59         book2.setId(2);
 60         book2.setName("三国演义");
 61         book2.setFlag("可借");
 62         
 63         list.add(book2);
 64         
 65         Book book3 = new Book();
 66         book3.setId(3);
 67         book3.setName("西游记");
 68         book3.setFlag("已借出");
 69         
 70         list.add(book3);
 71         
 72         return this.list;
 73     }
 74     
 75     /*
 76         添加
 77     */
 78     public void addBookToList(Book book) {
 79         if(this.list.size() <= maxCount) {
 80             this.list.add(book);
 81         }
 82     }
 83     
 84     /*
 85         删除
 86     */
 87     public boolean delBookFromList(Book book) {
 88         boolean flag = false ;
 89         Iterator<Book> it = this.list.iterator();
 90         while(it.hasNext()) {
 91             Book has_book = it.next();
 92             if(has_book.getName.equals(book.getName())){
 93                 it.remove();
 94                 flag = true;
 95             }
 96         }
 97         return flag;
 98     }
 99     
100     public boolean borrowBook(Book book){
101         boolean flag = false;
102         Iterator<Book> it = this.list.iterator();
103         while(it.hasNext()) {
104             Book has_book = it.next();
105             if(has_book.getName.equals(book.getName()){
106                 if("可借".equals(has_book.getFlag())){
107                     flag = true ;
108                 }
109             }
110         }
111         return flag ;
112     }
113     
114 }
115 
116 public class BookManager {
117     
118     public static void main(String args[]){
119         List<Book> bookList = new ArrayList<Book>();
120         Manager m = new Manager();
121         
122         bookList = m.getList();
123         
124         Iterator<Book> it = bookList.iterator();
125         while(it.hasNext()){
126             Book book = it.next();
127             System.out.println(
128                 "  编号:" + book.getId() +
129                 "  书名:" + book.getName() + 
130                 "  状态:" + book.getFlag()
131             );
132         }
133         
134         Book boo1 = new Book();
135         boo1.setId(4);
136         boo1.setName("大话西游");
137         boo1.setFlag("可借");
138         
139         m.addBookToList(boo1);
140         
141         Scanner scanner = new Scanner(System.in);
142         String name = scanner.next();
143         
144         Book removeBook = new Book();
145         removeBook.setName(name);
146         
147         boolean flag = m.delBookFromList(removeBook);
148         
149         Book b_Book = new Book();
150         b_Book.setName(scanner.next());
151         boolean  borrowFlag = m.borrowBook(b_Book);
152     }
153     
154 }