为log4j SMTPAppender中的邮件设置自定义主题

Question

I want that every time a message is logged for being sent as mail, different subject should be set. Below is log4j config for my smtpappender

log4j.appender.email=org.apache.log4j.net.SMTPAppender
log4j.appender.email.SMTPHost=localhost
log4j.appender.email.SMTPPort=25
log4j.appender.email.from="user@mydomain.com"
log4j.appender.email.to="user@mydomain.com"
log4j.appender.email.subject="test"
log4j.appender.email.layout=org.apache.log4j.PatternLayout
log4j.appender.email.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} :: %-5p :: %c{1}:%L :: Message :: %m%n

I know that SMTPAppender should be extended, but I can't find any satisfactory info about how I can write a class that will accept subject when a log event is triggered. for example

logger.error("Sample message");

For this log message subject should be accepted. How to achieve this?

Answer 1

You're right, you will face to the reload properties issue. Moreover I doubt that it would work on a concurrent system (2 errors raised at same time). Instead I would create a dedicated service to send the emails without using log4j. By this way, you should gain on the robustness aspect.