妥善处理一个的DbConnection的
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23-08-2019 - |
题
我有一个称为DatabaseHelper类是一个包装了的DbConnection。什么是设置的正确方法这个类using语句?我已经实现IDisposible,但我不知道何时何地我要调用的Connection.close()或Connection.Dispose()。
当我只是在我自己的Dispose()方法调用Connection.Dispose(),我有时会从我的DbConnection对象SocketException。我想这是因为旧的连接被保持开放,但没有附到异常的详细信息,所以我不能知道。
解决方案
从dispose方法中调用connection.Dispose()。你应该看看的标准图案用于实现IDisposable的,它前进超出简单地实现IDisposable接口,并允许用于布置非托管对象等:
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
if (!disposed)
{
if (disposing)
{
// Dispose managed resources.
}
// There are no unmanaged resources to release, but
// if we add them, they need to be released here.
}
disposed = true;
// If it is available, make the call to the
// base class's Dispose(Boolean) method
base.Dispose(disposing);
}
(来自 http://msdn.microsoft.com/en两者-us /库/ system.idisposable.aspx )。
其他提示
根据此新闻组:
下面是IDbConnection.Dispose()如何被实现(如反射器实用程序所示):
的SqlClient:
protected override void Dispose(bool disposing)
{
if (disposing)
{
switch (this._objectState)
{
case ConnectionState.Open:
{
this.Close();
break;
}
}
this._constr = null;
}
base.Dispose(disposing);
}
Odbc:
protected override void Dispose(bool disposing)
{
if (disposing)
{
this._constr = null;
this.Close();
CNativeBuffer buffer1 = this._buffer;
if (buffer1 != null)
{
buffer1.Dispose();
this._buffer = null;
}
}
base.Dispose(disposing);
}
OleDb:
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (this.objectState != 0)
{
this.DisposeManaged();
if (base.DesignMode)
{
OleDbConnection.ReleaseObjectPool();
}
this.OnStateChange(ConnectionState.Open, ConnectionState.Closed);
}
if (this.propertyIDSet != null)
{
this.propertyIDSet.Dispose();
this.propertyIDSet = null;
}
this._constr = null;
}
base.Dispose(disposing);
}
您的Dispose方法应该只尝试关闭连接,如果它是开放的。
此析构函数语法是actualy终结。终结时调用Dispose(假) 方法
#region IDisposable Members
private bool _isDisposed;
private void ThrowIfDisposed()
{
if (_isDisposed)
throw new ObjectDisposedException(this.GetType().Name);
}
protected virtual void Dispose(bool disposing)
{
if (!_isDisposed)
{
if (disposing)
{
//part 1 : disposing managed objects
_command.Dispose();
_command.Connection.Dispose();
if (_command.Transaction != null)
_command.Transaction.Dispose();
}
//part 2: disposing unmanged objects. Here there are no unmanged objects.
_isDisposed = true;
}
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
//~DbCommandExecutor() //No need of finalize here. Because there is no unmanged objects in my class. ie, no code in part 2.
//{
// Dispose(false);
//}
#endregion
有是的不需要终结器(或析构函数)语法的的强>直到码具有第2部分代码即可。否则,它应该为安全起见实现。也就是说,即使程序员没有正确调用Dispose方法,最终确定应清理非托管资源。
比较实施例:从MSDN
http://msdn.microsoft.com/en-我们/库/ system.idisposable.dispose.aspx & http://msdn.microsoft.com/en-us/library/fs2xkftw.aspx
刚刚完成了IDisposable实现模式,这是公约列入相关类的终结(析构函数),它调用Dispose()方法(通过假)。这作为一个故障安全机制,允许你如果类的消费者未调用Dispose()处置非托管对象。
~MyClass()
{
Dispose(false);
}