问题
I'm using the Microsoft Logging Application Block (version 5 beta 2) and I'm trying to dynamically set the file name of a log file to the year month and day (and then write a new log file every day). However, at runtime, the logger ignores any dynamic environment variables such as %date%, %time%, or %cd%. I can add static environment variables to the file name (such as %username%), but not dynamic environment variables. Does anyone know how to get the rolling flat file trace listener to dynamically set the date in the log file name?
(this is what I was setting the File Name as: Log_%date%.log)
回答1:
@Robertc, I know this question has been marked but I think I have a trick that you can use for your next project : Use your own environment variable!
E.g. Before you make any call to the Logging Block
Environment.SetEnvironmentVariable("MYDATE", "15/07/2010"); // << change the hardcoded date to get from DateTime
Debug.WriteLine (Environment.ExpandEnvironmentVariables(@"c:\Log\Log_%MYDATE%.log"));
In your app.config, in the appropriate Rolling flat file trace listener
FileName=Log_%MYDATE%.log
Note: This trick will only work if you restart your application daily.
回答2:
I gave up on the Logging Application Block and switched to log4net. Log4net lets me set the name of the log to today's date with a web.config setting. I wrote an article on Code Project that shows how to get log4net working with the Policy Injection Application Block here
来源：https://stackoverflow.com/questions/2647657/add-date-to-log-file-name-in-logging-application-block