是否可以在VB.NET中创建一个通用的数据库类？

We have 3 databases providers we use to connect to our databases: DB2, MS SQL, and Interbase. I would like to create a single generic database wrapper class that can be used to talk to all three just by passing in the correct connection string, username, password, and the provider desired.

我们有3个数据库提供程序用于连接到我们的数据库:DB2,MS SQL和Interbase。我想创建一个通用的数据库包装类,只需传入正确的连接字符串,用户名,密码和所需的提供程序,就可以用来与所有三个通信。

I don't want to have to add references and import all three providers in the database class. Is this possible?

我不想在数据库类中添加引用并导入所有三个提供程序。这可能吗?

I have done this before in Java using the Class.forName() function.

我以前在Java中使用Class.forName()函数完成了这个。

4 个解决方案

#1

There is an abstract factory built into .NET 2.0 or later, an example of its use would be:

.NET 2.0或更高版本中内置了一个抽象工厂,其使用示例如下:

Dim factory As System.Data.Common.DbProviderFactory
factory = System.Data.Common.DbProviderFactories.GetFactory("System.Data.SqlClient")

Dim conn As System.Data.Common.DbConnection = factory.CreateConnection()
conn.ConnectionString = "connectionString"
conn.Open()

There are methods on DbProviderFactory like CreateCommand, CreateDataAdapter, etc.

DbProviderFactory上有一些方法,比如CreateCommand,CreateDataAdapter等。

#2

If you do not want to have references to the individual providers in your application, you will need to handle this a little differently.

如果您不希望在应用程序中引用各个提供程序,则需要稍微改变一下。

There are two main options I see - the first (and easiest) would be to use a dependency injection framework to just plugin the appropriate provider at runtime. This is simple, clean, and works well.

我看到有两个主要选项 - 第一个(也是最简单的)是使用依赖注入框架在运行时插入适当的提供程序。这很简单,干净,效果很好。

You could do it yourself without that, though. Just make a general purpose base class that provides the interface, and, for each provider, make a separate assembly (so the references are separated) that implements this base class. You can then use Activator.CreateInstance to create an instance of the appropriate type at runtime.

不过,你可以自己做。只需创建一个提供接口的通用基类,并为每个提供程序创建一个单独的程序集(因此引用是分开的)来实现此基类。然后,您可以使用Activator.CreateInstance在运行时创建相应类型的实例。

#3

To expand on Patrick McDonald's answer, you can store the provider name and connection string in the <connectionStrings> section of your application configuration file. Then you don't need to have the providers hardcoded in the application:

要扩展Patrick McDonald的答案,您可以将提供程序名称和连接字符串存储在应用程序配置文件的部分中。然后,您不需要在应用程序中对提供程序进行硬编码:

ConnectionStringSettings c = ConfigurationManager.ConnectionStrings["MyConnectionName"];
if (c != null)
{
   DbProviderFactory factory = DbProviderFactories.GetFactory(c.ProviderName);
   IDbConnection connection = factory.CreateConnection();
   connection.ConnectionString = c.ConnectionString;
   ...
}

Where your application configuration file contains a connectionStrings section something like:

您的应用程序配置文件包含connectionStrings部分的位置如下:

<connectionStrings>
  <add name="MyConnectionName" providerName="System.Data.SqlClient" connectionString="Data Source=serverName;Initial Catalog=DBName;Integrated Security=True"/>
</connectionStrings>

#4

can you use framework 3.5 sp1?

你可以使用框架3.5 sp1吗?

if yes, you should look at Linq to Entity

如果是的话,你应该看看Linq to Entity

#1