简介本系列的最后一篇文章.第一部分如何描述,二部分如何取得描述.现在我们就要创建DAL库来使我们的标题可行.
设计DAL库我想创建的类库支持Sqlserver 和oledb.我把库分成了以下的部分:
Utility classesclass DALQueryBuilder生成sql语句更新物件.
class DALParameter生成参数保存在存储过程中.
class DALException继承于System.Exception , 数据库有异常时将会提供更多的信息.
Attribute classes参见第一篇.
DAL 本身class DALEngine这个抽象的类用于数据库操作,是数据库程序更加简单.它的虚拟和抽象的方法有不同的实施.
class DALSqlEngine
class DALOleDbEngine耧一眼DALEngine 类public
{
IDbConnection conn = = ArrayList parameters =
//
CommandBehavior behavior);
CommandBehavior behavior);
Type childType);
}
public
{
{
}
{
ArrayList result =
RetrieveChildObjects(customer.Id, result,
}
{
UpdateObjects(customer.Dependents);
}
}
看个例子:
public
{
DAL dal =
{
Contact contact =
contact.Name = ;
contact.Age = contact.Address = ;
contact.Address2 = contact.PostalCode = contact.City = ;
contact.State = contact.Country =
dal.UpdateObject(contact);
Console.WriteLine(contact);
Contact joaoCardoso = (Contact)dal.RetrieveObject( joaoCardoso.Age++;
Console.WriteLine(joaoCardoso);
Console.WriteLine(
Customer customer =
customer.Name = ;
customer.Age = customer.Address = ;
customer.Address2 = customer.PostalCode = customer.City = ;
customer.State = customer.Country = ;
customer.TotalPurchased += customer.NumberOfPurchases++;
dal.UpdateObject(customer);
Customer paul = (Customer)dal.RetrieveObject( Console.WriteLine(paul);
paul.TotalPurchased += 100M;
paul.NumberOfPurchases++;
dal.UpdateObject(paul);
{
CustomerDependent dependent = paul.NewDependent();
dependent.Name = ;
dependent.Age = paul.Dependents.Add(dependent);
dependent = paul.NewDependent();
dependent.Name = ;
dependent.Age = paul.Dependents.Add(dependent);
dependent = paul.NewDependent();
dependent.Name = ;
dependent.Age = dependent.Relationship = CustomerRelationship.Friend;
paul.Dependents.Add(dependent);
dal.UpdateCustomerDependents(paul);
}
{
Console.WriteLine(, paul.Name);
{
Console.WriteLine(, dependent.Id,
dependent.Name, dependent.Relationship);
dependent.Relationship = CustomerRelationship.Family;
}
dal.UpdateCustomerDependents(paul);
}
}
{
dal.Dispose();
}
}
Conclusion有老多局限性,需要我们去进一步实施思考,但是你理解了这些以后,我们就可以进行nhibernate的理解研究和应用了,祝你好运.
