如何用Java编写OS系统日志？

Question

Mac OS has an application called Console, which contains logged messages, errors, and faults. I believe the Windows equivalent is Event Viewer. I'd imagine there is one on Linux as well, but I don't know anything about it or where it is.

Is it possible to get a message from Java output to a system log like this? I'm writing a GUI-based application, so there is nothing running from the command line. The standard System.out or System.err probably won't be of much use in this case, unless I'm missing something.

I have written a simple logging service for my application that writes to a dedicated log file, but I want to have some kind of failsafe in case an I/O error occurs while attempting to write to this file.

I know the IDE will display output via System.out and System.err just fine, but this is for if the end-user encounters a problem like this.

As an example: I've written "codeless language modules" for the application TextWrangler on the Mac. These modules are read by TW at application startup, and if there is an error while processing them, errors get logged and can be viewed in the Mac Console application.

Answer 1

You can redirect System.out to a log file, and Mac's Console app is the default viewer for files ending in ".log".

One way this is commonly done is with a shell script that would invoke your Java program. In this Java 7 example, the output of invoking the main class MyClass is redirected to mylogfile.log. Everything that's written with System.out will be in mylogfile.log.

#!/bin/bash

for a in /path/to/my/jars/*
do 
CLASSPATH=$CLASSPATH:$a
done

java -Xms128M -Xmx128M -XX:MaxPermSize=128M -cp ${CLASSPATH} com.example.package.MyClass >> mylogfile.log

Answer 2

On Linux it is called as syslog. One of the ways that you can achieve logging to console on Mac will be to use log4j 'org.apache.log4j.net.SyslogAppender'.

I think this link should give you some kickstart in this direction.