Throw 和 Throw ex

在C#中，throw和throw ex都用于抛出异常，但它们在异常堆栈跟踪处理上有重要区别。

• throw ex resets the stack trace (so your errors would appear to originate from HandleException) 重置堆栈跟踪

• throw does not - the original offender would be preserved. 保留堆栈跟踪

Throw

{
    static void Main(string[] args)
    {
        try
        {
            SomeMethod();
        }
        catch (Exception)
        {
            Console.WriteLine("An error occurred.");

            throw;
        }
    }

    static void SomeMethod()
    {
        throw new NotImplementedException();
    }
}

运行堆栈：

An error occurred.
Unhandled exception. System.NotImplementedException: The method or operation is not implemented.
   at SomeMethod() in Test.cs:line 18
   at Main(String[] args) in Test.cs:line 6

保留了完整的堆栈跟踪

Throw preserves the stack trace. So lets say Source1 throws Error1 , its caught by Source2 and Source2 says throw then Source1 Error + Source2 Error will be available in the stack trace.

---

Throw ex

{
    static void Main(string[] args)
    {
        try
        {
            SomeMethod();
        }
        catch (Exception ex)
        {
            Console.WriteLine("An error occurred.");

            throw ex;
        }
    }

    static void SomeMethod()
    {
        throw new NotImplementedException();
    }
}

通常你会看到一个 build warning:
Rethrow to preserve stack details: https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca2200

运行堆栈：

An error occurred.
Unhandled exception. System.NotImplementedException: The method or operation is not implemented.
   at Main(String[] args) in Test.cs:line 12

重置堆栈跟踪，丢失原始抛出位置信息

Throw ex does not preserve the stack trace. So all errors of Source1 will be wiped out and only Source2 error will sent to the client.