C# 在 using 语句中抛出异常时，是否仍会调用 Dispose？
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Does Dispose still get called when exception is thrown inside of a using statement?
提问by Brian Kim
In the example below, is the connection going to close and disposed when an exception is thrown if it is within a usingstatement?
在下面的示例中，如果在using语句中抛出异常，连接是否会关闭并处理？
using (var conn = new SqlConnection("..."))
{
conn.Open();
// stuff happens here and exception is thrown...
}
I know this code below will make sure that it does, but I'm curious how using statement does it.
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();
}
Related:
有关的：
What is the proper way to ensure a SQL connection is closed when an exception is thrown?在抛出异常时确保 SQL 连接关闭的正确方法是什么？采纳答案by Jeff Yates
Yes, usingwraps your code in a try/finally block where the finallyportion will call Dispose()if it exists. It won't, however, call Close()directly as it only checks for the IDisposableinterface being implemented and hence the Dispose()method.
是的，using将您的代码包装在 try/finally 块中，如果存在，该finally部分将调用该块Dispose()。但是，它不会Close()直接调用，因为它只检查IDisposable正在实现的接口以及Dispose()方法。
See also:
也可以看看：
- 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
回答by Florin Sabau
This is how reflector decodes the IL generated by your code:
这是反射器如何解码由您的代码生成的 IL：
private static void Main(string[] args)
{
SqlConnection conn = new SqlConnection("...");
try
{
conn.Open();
DoStuff();
}
finally
{
if (conn != null)
{
conn.Dispose();
}
}
}
So the answer is yes, it will close the connection if
所以答案是肯定的，如果它会关闭连接
DoStuff()抛出异常。
回答by Chad
Dispose() doesn't get called in this code.
Dispose() 在这段代码中没有被调用。
class Program {
static void Main(string[] args) {
using (SomeClass sc = new SomeClass())
{
string str = sc.DoSomething();
sc.BlowUp();
}
}
}
public class SomeClass : IDisposable {
private System.IO.StreamWriter wtr = null;
public SomeClass() {
string path = System.IO.Path.GetTempFileName();
this.wtr = new System.IO.StreamWriter(path);
this.wtr.WriteLine("SomeClass()");
}
public void BlowUp() {
this.wtr.WriteLine("BlowUp()");
throw new Exception("An exception was thrown.");
}
public string DoSomething() {
this.wtr.WriteLine("DoSomething()");
return "Did something.";
}
public void Dispose() {
this.wtr.WriteLine("Dispose()");
this.wtr.Dispose();
}
}
