struts和hibernate简单问题

}

public int hashCode(){

if (this.hashValue == 0){

int result = 17;

int idValue = this.getId() == null ? 0 : this.getId().hashCode();

result = result * 37 + idValue;

this.hashValue = result;

}

return this.hashValue;

}

}

public class Customer extends AbstractCustomer implements Serializable

{

public Customer()

{

}

public Customer(java.lang.Integer id)

{

super(id);

}

}

public abstract class AbstractBook implements Serializable

{

private int hashValue = 0;

private java.lang.Integer id;

private Customer customer;

private java.lang.String title;

private java.lang.String author;

private java.lang.Short borrowallowed;

public AbstractBook(){}

public AbstractBook(java.lang.Integer id){