//User實體表示使用者,Book實體表示書籍,為了描述使用者收藏的書籍,可以在User和Book之間建立ManyToMany關聯
     @Entity
     public class User {
       private List books;
       @ManyToMany(targetEntity=package.Book.class)
       public List getBooks() {
           return books;
       }
       public void setBooks(List books) {
           
 
this.books=books;
       }
     }
 
     @Entity
     public class Book {
       private List users;
       @ManyToMany(targetEntity=package.Users.class, mappedBy="books")
       public List getUsers() {
           return users;
       }
       public void setUsers(List users) {
           this.users=users;
       }
     }