如何转换我的MySQL连接到一个类在VB.2010年净

Question

我有多个表单，每个表单执行特定的任务，需要连接到MySQL服务器。
在每个表单上声明:

Imports MySql.Data.SqlClient
Dim myConnObj As New MySqlConnection

我这样使用它们:

myConnObj = New MySqlConnection()
myConnObj.ConnectionString = "Server=" & db_Server & ";Database=" & dbase & ";UID= & "db_UserID & ";PWD=" & db_Password
myConnObj.Open()
''Things to do here
myConnObj.Close

我想把这个过程转换成一个类，以尽量减少代码，它应该可以通过所有的形式，但我不知道从哪里开始。虽然我已经在VB中创建了一个名为clsconnect。VB的空类
请注意，"dbase"(我将连接到的数据库)应该是不同的。

Answer 1

你可以采用单例方法:

VB。NET:

Public Class DBase
    #Region "Singleton"
    Private Shared instances As New Dictionary(Of [String], DBase)()
    Public Shared Function GetInstance(dbname As [String]) As DBase
        If Not instances.ContainsKey(dbname) Then
            instances(dbname) = New DBase(dbname)
        End If
        Return instances(dbname)
    End Function
    #End Region
    Private connection As MySqlConnection
    Private Sub New(dbase As [String])
        Me.connection = New MySqlConnection()
        Me.connection.ConnectionString = "...connection string implementing dbase..."
        Me.connection.Open()
    End Sub
    Protected Overrides Sub Finalize()
        Try
            Me.connection.Close()
        Finally
            MyBase.Finalize()
        End Try
    End Sub
    #Region "Database Methods"
    ' add the various method calls to the database here.
    #End Region
End Class
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c # 35;

public class DBase
{
  #region Singleton
  private static Dictionary<String, DBase> instances = new Dictionary<String, DBase>();
  public static DBase GetInstance(String dbname)
  {
    if (!instances.ContainsKey(dbname))
    {
      instances[dbname] = new DBase(dbname);
    }
    return instances[dbname];
  }
  #endregion
  private MySqlConnection connection;
  private DBase(String dbase)
  {
    this.connection = new MySqlConnection();
    this.connection.ConnectionString = "...connection string implementing dbase...";
    this.connection.Open();
  }
  ~DBase()
  {
    this.connection.Close();
  }
  #region Database Methods
  // add the various method calls to the database here.
  #endregion
}

那么你可以从任何地方访问它，并调用它:

VB。净

Dim db As DBase = DBase.GetInstance("DEMO")
Dim name As [String] = db.GetUsernameFromEmail("[e-mail]")

c # 35;

DBase db = DBase.GetInstance("DEMO");
String name = db.GetUsernameFromEmail("[e-mail]");

非常粗糙，但能完成任务。您可以更详细地说明验证、连接检查、清理和(可能的)线程安全，但我将保持示例简短。