Question

我是开发抽象工厂模式的新手，并希望在数据层中创建一个抽象工厂，它将帮助我将此层链接到任何其他数据库，例如sql和oracle。你能帮我完成这项任务吗？请注意，数据库的连接字符串将在此层中找到，而不是在演示文稿中。

由于

EDITED

public abstract class Database
{
    public string connectionString;

    #region Abstract Functions

    public abstract IDbConnection CreateConnection();
    public abstract IDbCommand CreateCommand();
    public abstract IDbConnection CreateOpenConnection();
    public abstract IDbCommand CreateCommand(string commandText, IDbConnection connection);
    public abstract IDbCommand CreateStoredProcCommand(string procName, IDbConnection connection);
    public abstract IDataParameter CreateParameter(string parameterName, object parameterValue);

    #endregion
}

public class SQLDatabase : Database
{
    public override IDbConnection CreateConnection()
    {
        return new SqlConnection(connectionString);
    }

    public override IDbCommand CreateCommand()
    {
        return new SqlCommand();
    }

    public override IDbConnection CreateOpenConnection()
    {
        SqlConnection connection = (SqlConnection)CreateConnection();
        connection.Open();

        return connection;
    }

    public override IDbCommand CreateCommand(string commandText, IDbConnection connection)
    {
        SqlCommand command = (SqlCommand)CreateCommand();

        command.CommandText = commandText;
        command.Connection = (SqlConnection)connection;
        command.CommandType = CommandType.Text;

        return command;
    }

    public override IDbCommand CreateStoredProcCommand(string procName, IDbConnection connection)
    {
        SqlCommand command = (SqlCommand)CreateCommand();

        command.CommandText = procName;
        command.Connection = (SqlConnection)connection;
        command.CommandType = CommandType.StoredProcedure;

        return command;
    }

    public override IDataParameter CreateParameter(string parameterName, object parameterValue)
    {
        return new SqlParameter(parameterName, parameterValue);
    }
}

这是我创建的两个课程。

Answer 1

功能已存在。

将连接字符串添加到app / webb.config：

<connectionStrings>
    <add name="TheDatabase" providerName="System.Data.OleDb" connectionString="Provider=OraOLEDB.Oracle.1;Persist Security Info=False;User Id=xxx;Password=yyy;Data Source=zzzz;Extended Properties="/>
  </connectionStrings>

使用工厂建立连接：

var connectionString = ConfigurationManager.ConnectionStrings["TheDatabase"];
var providerName = connectionString.ProviderName;
var factory = DbProviderFactories.GetFactory(providerName);

获取连接：

var connection = factory.CreateConnection();

获取命令：

var command == connection.CreateCommand();

您唯一需要做的就是在app / web.config中切换驱动程序。不需要进行其他更改。

更新

public class Database
{
    public static IDbConnection CreateOpenConnection()
    {
        var connectionString = ConfigurationManager.ConnectionStrings["TheDatabase"];
        var providerName = connectionString.ProviderName;
        var factory = DbProviderFactories.GetFactory(providerName);
        var connection = factory.CreateConnection();
        connection.Open();
        return connection;
    }
}

class FlowerManager : DataWorker
{
    public static void GetFlowers()
    {
        using (IDbConnection connection = Database.CreateOpenConnection())
        {
            using (IDbCommand command = connection.CreateCommand("SELECT * FROM FLOWERS", connection))
            {
                using (IDataReader reader = command.ExecuteReader())
                {
                    // ...
                }
            }
        }
    }
}

Answer 2

可以从

获得许多所需的功能

 System.Data.Common.DbProviderFactories

您可以获取大多数dotnet-databaseproviders实现的System.Data.Common.DbProviderFactory项。

<强>更新：

havig你自己的工厂很好。如果您想了解工作数据库工厂的示例，请参阅

的源代码

queryexpress一个工作数据库 - 查询gui，
queryexplus一个queryexpress的旋转
mygeneration一个连接到许多不同数据库的代码生成器
NHibernate具有适用于许多数据库的复杂驱动程序模式

Answer 3

我没有“createcommand”或“createconnection”方法。

更好的方法是让每个访问方法（如“GetAccounts”）处理自己的连接/命令实例化。

Connection和Command对象实现IDisposable。因此，最好使用using语句来创建和处理这些语句。你现在拥有它可能会导致大量内存问题。

此外，CreateParameter方法似乎没有提供任何真正的好处，而只是在需要创建这些参数的代码中调用“new SqlParameter”。

我会做以下事情：

public interface IDbAccess {
  String ConnectionString;

  Collection<Account> GetAccountsById(Int32 id);
  Boolean StoreAccount(Account acct);
}

public class SqlDatabase : IDbAccess {
  public String ConnectionString {get; set;}

  public SqlDatabase(String connection) {
    ConnectionString = connection;
  }

  public Collection<Account> GetAccountsById(Int32 id) {
    using (SqlConnection connect = new SqlConnection(ConnectionString)) { 
       using (SqlCommand cmd = new SqlCommand(connect)) {
          /// etc.
        }
    }
  }
}

这样，您的数据层特定于您提供的功能。像Enterprise Library这样的db访问已有很好的包装器。你采取的方法不会增加任何内容并引入错误。

此外，这种方法意味着您可以实现非数据库提供程序，如XML，Web服务等，无需更改代码。

Answer 4

嗨，大家好我知道这是老帖子，但我想和你分享一些东西。

企业库和OleDb有一些问题，当你想要插入大于32k的图像时，它会抛出异常，所以我已经完成了解决这个问题：

创建一个项目，您可以调用CustomProvider

创建一个Classe，您将其称为数据库

 public abstract class Database
 {
    public string ConnectionString { get; set; } // Preciso uma variavel para guardar o ConnectionString
    public IDbConnection Connection { get; set; }


    //public abstract string ProviderName { get; } // Preciso uma variavel para guardar o ConnectionString


    //public abstract IDbConnection CreateConnection(string ConnectionString);

    public abstract IDbConnection CreateConnection(); // Preciso um Metodo Abstract para CreateConnection Para Tratar da Connection
    public abstract IDbCommand CreateCommand();

    }
}

创建第二级OracleDatabase.cs

创建第三课SQLDatabase.cs

 public class OracleDatabase : Database
 {

  public override IDbConnection CreateConnection()
  {
      return new OracleConnection(ConnectionString);
  }

  public override IDbCommand CreateCommand()
  {
      return new OracleCommand();
  }

  public override IDbConnection CreateOpenConnection()
  {
      OracleConnection connection = (OracleConnection)CreateConnection();
      connection.Open();

      return connection;
  }

  public override IDbCommand CreateCommand(string commandText, IDbConnection connection)
  {
      OracleCommand command = (OracleCommand)CreateCommand();

      command.CommandText = commandText;
      command.Connection = (OracleConnection)connection;
      command.CommandType = CommandType.Text;

      return command;
  }
}

public class SQLDatabase：Database {

  public override IDbConnection CreateConnection()
  {
      return new SqlConnection(ConnectionString);
  }

  public override IDbCommand CreateCommand()
  {
      return new SqlCommand();
  }

  public override IDbConnection CreateOpenConnection()
  {
      SqlConnection connection = (SqlConnection)CreateConnection();
      connection.Open();

      return connection;
  }

  public override IDbCommand CreateCommand(string commandText, IDbConnection connection)
  {
      SqlCommand command = (SqlCommand)CreateCommand();

      command.CommandText = commandText;
      command.Connection = (SqlConnection)connection;
      command.CommandType = CommandType.Text;

      return command;
  }

  public override IDbCommand CreateStoredProcCommand(string procName, IDbConnection connection)
  {
      SqlCommand command = (SqlCommand)CreateCommand();

      command.CommandText = procName;
      command.Connection = (SqlConnection)connection;
      command.CommandType = CommandType.StoredProcedure;

      return command;
    }
 }

然后是程序

    Database db = Factory.CreateDatabase("ConnectionString");

    try
    {
        using (IDbConnection w_connection = db.Connection)
        {
            w_connection.Open();

            IDbTransaction transation = w_connection.BeginTransaction();

            IDbCommand dbcomand = db.CreateStoredProcCommand("INSERTTEST");

            db.AddInParameter(dbcomand, "@ATTCH", DbType.Binary, bytes);
            db.ExecuteNonQuery(dbcomand, transation);

            transation.Commit();
        }
    }
    catch (Exception)
    {

    }
  }

您必须覆盖主类中所有已定义的方法

创建 Factory.cs

public static Database CreateDatabase(string ConnectionString)
{
    //var Conn = ConfigurationManager.ConnectionStrings[ConnectionString].ToString();


    if (string.IsNullOrEmpty(ConnectionString))
        throw new Exception("Connectionstring Not Found" + ConnectionString);

    Database db = null;

    if (ConfigurationManager.ConnectionStrings[ConnectionString].ProviderName.Contains("Oracle"))
    {
        db = new OracleDatabase();
        db.ConnectionString = GetConnectionString(ConnectionString);
        db.Connection = db.CreateConnection();
    }
    else
    {
        db = new SQLDatabase();
        db.ConnectionString = GetConnectionString(ConnectionString);
        db.Connection = db.CreateConnection();
    }


    return db;
}

数据层抽象工厂

4 个答案:

更新