c# - 在 using 语句中抛出异常时，是否仍会调用 Dispose？

Question

在下面的示例中，如果在 using 语句中抛出异常，连接是否会关闭并释放？

using (var conn = new SqlConnection("..."))
{
    conn.Open();
    // stuff happens here and exception is thrown...
}

我知道下面的这段代码将确保它确实如此，但我很好奇 using 语句是如何做到的。

var conn;
try
{
    conn = new SqlConnection("...");
    conn.Open();
    // stuff happens here and exception is thrown...
}
// catch it or let it bubble up
finally
{
    conn.Dispose();
}

相关:

What is the proper way to ensure a SQL connection is closed when an exception is thrown?

Answer 1

是的，using 将您的代码包装在一个 try/finally block 中，其中 finally 部分将调用 Dispose()(如果它存在)。但是，它不会直接调用 Close()，因为它只检查正在实现的 IDisposable 接口(interface)以及 Dispose() 方法.

另见:

• Intercepting an exception inside IDisposable.Dispose
• What is the proper way to ensure a SQL connection is closed when an exception is thrown?
• C# "Using" Syntax
• C# USING keyword - when and when not to use it?
• 'using' statement vs 'try finally'
• What is the C# Using block and why should I use it?
• Disposable Using Pattern
• Does End Using close an open SQL Connection