TransactionScope.Dispose 方法
定义
重要
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结束事务范围。
public:
virtual void Dispose();public void Dispose ();abstract member Dispose : unit -> unit
override this.Dispose : unit -> unitPublic Sub Dispose ()实现
示例
以下示例演示如何使用 TransactionScope 类定义一个代码块来参与事务。
// This function takes arguments for 2 connection strings and commands to create a transaction
// involving two SQL Servers. It returns a value > 0 if the transaction is committed, 0 if the
// transaction is rolled back. To test this code, you can connect to two different databases
// on the same server by altering the connection string, or to another 3rd party RDBMS by
// altering the code in the connection2 code block.
static public int CreateTransactionScope(
string connectString1, string connectString2,
string commandText1, string commandText2)
{
// Initialize the return value to zero and create a StringWriter to display results.
int returnValue = 0;
System.IO.StringWriter writer = new System.IO.StringWriter();
try
{
// Create the TransactionScope to execute the commands, guaranteeing
// that both commands can commit or roll back as a single unit of work.
using (TransactionScope scope = new TransactionScope())
{
using (SqlConnection connection1 = new SqlConnection(connectString1))
{
// Opening the connection automatically enlists it in the
// TransactionScope as a lightweight transaction.
connection1.Open();
// Create the SqlCommand object and execute the first command.
SqlCommand command1 = new SqlCommand(commandText1, connection1);
returnValue = command1.ExecuteNonQuery();
writer.WriteLine("Rows to be affected by command1: {0}", returnValue);
// If you get here, this means that command1 succeeded. By nesting
// the using block for connection2 inside that of connection1, you
// conserve server and network resources as connection2 is opened
// only when there is a chance that the transaction can commit.
using (SqlConnection connection2 = new SqlConnection(connectString2))
{
// The transaction is escalated to a full distributed
// transaction when connection2 is opened.
connection2.Open();
// Execute the second command in the second database.
returnValue = 0;
SqlCommand command2 = new SqlCommand(commandText2, connection2);
returnValue = command2.ExecuteNonQuery();
writer.WriteLine("Rows to be affected by command2: {0}", returnValue);
}
}
// The Complete method commits the transaction. If an exception has been thrown,
// Complete is not called and the transaction is rolled back.
scope.Complete();
}
}
catch (TransactionAbortedException ex)
{
writer.WriteLine("TransactionAbortedException Message: {0}", ex.Message);
}
// Display messages.
Console.WriteLine(writer.ToString());
return returnValue;
}
' This function takes arguments for 2 connection strings and commands to create a transaction
' involving two SQL Servers. It returns a value > 0 if the transaction is committed, 0 if the
' transaction is rolled back. To test this code, you can connect to two different databases
' on the same server by altering the connection string, or to another 3rd party RDBMS
' by altering the code in the connection2 code block.
Public Function CreateTransactionScope( _
ByVal connectString1 As String, ByVal connectString2 As String, _
ByVal commandText1 As String, ByVal commandText2 As String) As Integer
' Initialize the return value to zero and create a StringWriter to display results.
Dim returnValue As Integer = 0
Dim writer As System.IO.StringWriter = New System.IO.StringWriter
Try
' Create the TransactionScope to execute the commands, guaranteeing
' that both commands can commit or roll back as a single unit of work.
Using scope As New TransactionScope()
Using connection1 As New SqlConnection(connectString1)
' Opening the connection automatically enlists it in the
' TransactionScope as a lightweight transaction.
connection1.Open()
' Create the SqlCommand object and execute the first command.
Dim command1 As SqlCommand = New SqlCommand(commandText1, connection1)
returnValue = command1.ExecuteNonQuery()
writer.WriteLine("Rows to be affected by command1: {0}", returnValue)
' If you get here, this means that command1 succeeded. By nesting
' the using block for connection2 inside that of connection1, you
' conserve server and network resources as connection2 is opened
' only when there is a chance that the transaction can commit.
Using connection2 As New SqlConnection(connectString2)
' The transaction is escalated to a full distributed
' transaction when connection2 is opened.
connection2.Open()
' Execute the second command in the second database.
returnValue = 0
Dim command2 As SqlCommand = New SqlCommand(commandText2, connection2)
returnValue = command2.ExecuteNonQuery()
writer.WriteLine("Rows to be affected by command2: {0}", returnValue)
End Using
End Using
' The Complete method commits the transaction. If an exception has been thrown,
' Complete is called and the transaction is rolled back.
scope.Complete()
End Using
Catch ex As TransactionAbortedException
writer.WriteLine("TransactionAbortedException Message: {0}", ex.Message)
End Try
' Display messages.
Console.WriteLine(writer.ToString())
Return returnValue
End Function
注解
调用此方法会标记事务范围的末尾。 如果对象 TransactionScope 创建了事务并在 Complete 范围上调用，则当调用此方法时，该 TransactionScope 对象会尝试提交事务。 在这种情况下，此方法会阻止事务处理的第一个阶段完成。 第一阶段在事务中的所有资源管理器和登记都投票决定事务结果后结束，并且 TransactionManager 已持续决定提交或中止事务。 处理的第二个阶段始终是异步的。 因此，不能保证刚从给定事务内提交的数据在不使用其他事务查看此数据时立即可用。
使用 C# using 构造可确保即使发生异常，也调用此方法。 在调用此方法之后所发生的异常不会影响事务。 此方法还会将环境事务还原到原始状态。 如果事务实际上未提交，则会引发 A TransactionAbortedException 。
由于此方法会阻止事务处理的第一个阶段完成，因此在 Windows Form (WinForm) 应用程序中使用此方法时，应非常小心，否则会发生死锁。 例如，如果在一个 WinForm Control 事件中调用此方法 (，请单击按钮) ，并使用同步 Invoke 方法指示控件执行某些 UI 任务 (，例如，在处理事务过程中更改颜色) ，将发生死锁。 这是因为 Invoke 该方法是同步的，并阻止工作线程，直到 UI 线程完成其作业。 但是，在我们的方案中，UI 线程也在等待工作线程提交事务。 结果是，没有一个能够继续，范围会无限期地等待提交完成。 应尽可能使用，而不是尽可能使用BeginInvokeInvoke，因为它是异步的，因此更容易出现死锁。
有关如何使用此方法的详细信息，请参阅 使用事务范围实现隐式事务 主题。