A few years ago I knocked up a Log4J appender that used ANSI escape sequences to colour-code log messages based on their priority. This is quite an effective way of dealing with the information overload from console logging without having to disable the lower log levels. Your eyes are immediately drawn towards the more important messages but the detailed information is still there for you to diagnose the problems.
Unfortunately I can’t get it to work under Windows (even using Cygwin), but if you are using an ANSI-enabled terminal (such as most of the Linux terminals), it’s pretty helpful. It’s also trivial to implement, so here it is:
import org.apache.log4j.ConsoleAppender; import org.apache.log4j.Level; import org.apache.log4j.Priority; import org.apache.log4j.spi.LoggingEvent; /** * Colour-coded console appender for Log4J. */ public class ANSIConsoleAppender extends ConsoleAppender { private static final int NORMAL = 0; private static final int BRIGHT = 1; private static final int FOREGROUND_BLACK = 30; private static final int FOREGROUND_RED = 31; private static final int FOREGROUND_GREEN = 32; private static final int FOREGROUND_YELLOW = 33; private static final int FOREGROUND_BLUE = 34; private static final int FOREGROUND_MAGENTA = 35; private static final int FOREGROUND_CYAN = 36; private static final int FOREGROUND_WHITE = 37; private static final String PREFIX = "\u001b["; private static final String SUFFIX = "m"; private static final char SEPARATOR = ';'; private static final String END_COLOUR = PREFIX + SUFFIX; private static final String FATAL_COLOUR = PREFIX + BRIGHT + SEPARATOR + FOREGROUND_RED + SUFFIX; private static final String ERROR_COLOUR = PREFIX + NORMAL + SEPARATOR + FOREGROUND_RED + SUFFIX; private static final String WARN_COLOUR = PREFIX + NORMAL + SEPARATOR + FOREGROUND_YELLOW + SUFFIX; private static final String INFO_COLOUR = PREFIX + NORMAL+ SEPARATOR + FOREGROUND_GREEN + SUFFIX; private static final String DEBUG_COLOUR = PREFIX + NORMAL + SEPARATOR + FOREGROUND_CYAN + SUFFIX; private static final String TRACE_COLOUR = PREFIX + NORMAL + SEPARATOR + FOREGROUND_BLUE + SUFFIX; /** * Wraps the ANSI control characters around the * output from the super-class Appender. */ protected void subAppend(LoggingEvent event) { this.qw.write(getColour(event.getLevel())); super.subAppend(event); this.qw.write(END_COLOUR); if(this.immediateFlush) { this.qw.flush(); } } /** * Get the appropriate control characters to change * the colour for the specified logging level. */ private String getColour(Level level) { switch (level.toInt()) { case Priority.FATAL_INT: return FATAL_COLOUR; case Priority.ERROR_INT: return ERROR_COLOUR; case Priority.WARN_INT: return WARN_COLOUR; case Priority.INFO_INT: return INFO_COLOUR; case Priority.DEBUG_INT:return DEBUG_COLOUR; default: return TRACE_COLOUR; } } } |
This should work with both the latest version of Log4J, which includes a TRACE level, and the previous versions. Using it is simply a matter of making sure the class is on the classpath with Log4J and referring to it from the configuration file.