使用属性和反射过渡从数据存取层到业务物件 - III

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:

Utilityclasses

classDALQueryBuilder

生成sql语句更新物件.

classDALParameter

生成参数保存在存储过程中.

classDALException

继承于

System.Exception

,数据库有异常时将会提供更多的信息.

Attributeclasses

参见第一篇.

DAL本身

classDALEngine

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.

classDALSqlEngine

classDALOleDbEngine

耧一眼DALEngine类

publicabstractclassDALEngine:IDisposable

{

//

//privatedatamembers

//

IDbConnectionconn=null;

stringconnectionString="";

ArrayListparameters=newArrayList();

boolcanClose=true;

//constructor

publicDALEngine(stringconnectionString);

publicboolCanClose;

publicstringConnectionString;

protectedIDbConnectionConnection;

protectedArrayListParameters;

publicvoidClose();

publicvoidDispose();

//

//methodsthatmustbeoverridewithaspecificdataprovider

//implementationpleaseseetheimplementationofDALSqlEngine

//orDALOleDbEngine

//

protectedabstractIDbConnectionGetConnection();

protectedabstractIDbCommandCreateCommand(stringspName);

publicabstractvoidExecSP_DataSet(stringspName,DataSetdataSet,

stringtableName);

publicabstractvoidExecQuery_DataSet(stringquery,DataSetdataSet,

stringtableName);

//

//relatedtostoredprocedureparameters

//

publicDALParameterGetParameter(stringname);

voidUpdateOutputParameters(IDbCommandcmd);

publicvoidAddParameter(DALParameterparam);

publicvoidClearParameters();

//

//forthosethatusestoredprocedures

//

publicIDataReaderExecSP_DataReader(stringspName);

publicIDataReaderExecSP_DataReader(stringspName,

CommandBehaviorbehavior);

publicobjectExecSP_Scalar(stringspName);

publicintExecSP_NonQuery(stringspName);

//

//methodsforthosethatuseplainSQLstatements

//

publicIDataReaderExecQuery_DataReader(stringquery,

CommandBehaviorbehavior);

publicIDataReaderExecQuery_DataReader(stringquery);

publicobjectExecQuery_Scalar(stringquery);

publicintExecQuery_NonQuery(stringquery);

//

//Businessobjectsmethods

//

publicstaticobjectCreateFromReader(IDataReaderreader,TypeobjType);

publicobjectRetrieveObject(objectkeyValue,TypeobjType);

publicintRetrieveChildObjects(objectforeignKeyValue,ArrayListobjects,

TypechildType);

voidUpdateObjectSql(objecto,DataTableAttributedataTable);

voidUpdateObjectStoredProcedure(objecto,DataTableAttributedataTable);

publicvoidUpdateObject(objecto);

publicvoidUpdateObjects(IEnumerableenumObjects);

}

publicclassDAL:DALSqlEngine

{

conststringCONN_STRING="server=localhost;uid=sa;pwd=;database=pubs";

publicDAL():base(CONN_STRING)

{

}

publicArrayListGetCustomerDependents(Customercustomer)

{

ArrayListresult=newArrayList();

RetrieveChildObjects(customer.Id,result,typeof(CustomerDependent));

returnresult;

}

publicvoidUpdateCustomerDependents(Customercustomer)

{

UpdateObjects(customer.Dependents);

}

}

看个例子:

publicstaticvoidMain()

{

DALdal=newDAL();

try

{

Contactcontact=newContact();

contact.Name="JoaoCardoso";

contact.Age=23;

contact.Address="Av.RioBranco,202/121";

contact.Address2="Centro";

contact.PostalCode="09029-901";

contact.City="SaoPaulo";

contact.State="SP";

contact.Country="Brazil";

dal.UpdateObject(contact);

Console.WriteLine(contact);

ContactjoaoCardoso=(Contact)dal.RetrieveObject(1,typeof(Contact));

joaoCardoso.Age++;

Console.WriteLine(joaoCardoso);

Console.WriteLine("");

Customercustomer=newCustomer();

customer.Name="PaulNoyter";

customer.Age=34;

customer.Address="AllSt,2202/2121";

customer.Address2="Downville";

customer.PostalCode="90931";

customer.City="LosAngeles";

customer.State="CA";

customer.Country="UnitedStates";

customer.TotalPurchased+=1900.87M;

customer.NumberOfPurchases++;

dal.UpdateObject(customer);

Customerpaul=(Customer)dal.RetrieveObject(1,typeof(Customer));

Console.WriteLine(paul);

paul.TotalPurchased+=100M;

paul.NumberOfPurchases++;

dal.UpdateObject(paul);

if(paul.Dependents.Count==0)

{

CustomerDependentdependent=paul.NewDependent();

dependent.Name="MarieNoyter";

dependent.Age=31;

paul.Dependents.Add(dependent);

dependent=paul.NewDependent();

dependent.Name="MarkNoyter";

dependent.Age=10;

paul.Dependents.Add(dependent);

dependent=paul.NewDependent();

dependent.Name="ClaudiaSnorg";

dependent.Age=32;

dependent.Relationship=CustomerRelationship.Friend;

paul.Dependents.Add(dependent);

dal.UpdateCustomerDependents(paul);

}

else

{

Console.WriteLine("Dependentsof{0}",paul.Name);

foreach(CustomerDependentdependentinpaul.Dependents)

{

Console.WriteLine("<Dependent>{0}-{1}[{2}]",dependent.Id,

dependent.Name,dependent.Relationship);

dependent.Relationship=CustomerRelationship.Family;

}

dal.UpdateCustomerDependents(paul);

}

}

finally

{

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.