Log4j2 - Transaction logging in file and application logging on console

Question

I am developing a logger where certain transaction messages need to be logged to a file and some application logs need to be logged to the console. Currently, the transaction messages are also being logged onto the console and I want to avoid that.

for eg:

if i write logger.info("application process started"); this needs to be logged on console .

and when i write logger.info(new ObjectArrayMessage("msg1","msg2","msg3")); this need to be logged to a csv file .

This is my current output:

19:18:42.230 [main5] INFO  New.CSVlog.App - application process started
19:18:42.233 [main5] INFO  New.CSVlog.App - [msg1,msg2,msg3]

I want to log only the first log to the console and the second one to the CSV file.

I have the following properties file:

appenders = csvFile, console

appender.csvFile.type = RollingFile
appender.csvFile.name = CSVFILE
appender.csvFile.fileName = csvLog.csv
appender.csvFile.filePattern= csvLog-%d{MM-dd-yyyy}-%i.csv
appender.csvFile.layout.type = CsvParameterLayout
appender.csvFile.layout.delimiter = ,
appender.csvFile.layout.header = column1,column2,column3\n
appender.csvFile.policies.type = Policies
appender.csvFile.policies.time.type = TimeBasedTriggeringPolicy
appender.csvFile.policies.time.interval = 1
appender.csvFile.policies.time.modulate = true
appender.csvFile.policies.size.type = SizeBasedTriggeringPolicy
appender.csvFile.policies.size.size=10MB
appender.csvFile.strategy.type = DefaultRolloverStrategy
appender.csvFile.strategy.max = 200

appender.console.type = Console
appender.console.name = consoleLog
appender.console.layout.type = PatternLayout
appender.console.layout.pattern = %d{HH:mm:ss.SSS} [%t5] %-5level %logger{36} - %msg%n


rootLogger.level =debug
rootLogger.appenderRefs = csvFile, consoleLog
rootLogger.appenderRef.csvFile.ref = CSVFILE


rootLogger.appenderRef.console.ref = consoleLog

Can anyone please help me to use the same logger for both transaction and application logging? and what changes do I need to make in my properties file? Thanks!

Answer 1

You can use Filter s to seperate ObjectArrayMessage messages from the rest (cf. documentation ). Although there is no built-in filter that checks the class of the Message object, you can easily write one:

@Plugin(name = "ObjectArrayMessageFilter", category = Node.CATEGORY, elementType = Filter.ELEMENT_TYPE)
public class ObjectArrayMessageFilter extends AbstractFilter {

    public static class Builder extends AbstractFilterBuilder<Builder>
            implements org.apache.logging.log4j.core.util.Builder<ObjectArrayMessageFilter> {

        @Override
        public ObjectArrayMessageFilter build() {
            return new ObjectArrayMessageFilter(getOnMatch(), getOnMismatch());
        }
    }

    @PluginBuilderFactory
    public static Builder newBuilder() {
        return new Builder();
    }

    private ObjectArrayMessageFilter(Result onMatch, Result onMismatch) {
        super(onMatch, onMismatch);
    }

    private static Result filter(Object msg) {
        return msg instanceof ObjectArrayMessage ? onMatch : onMismatch;
    }

    @Override
    public Result filter(final LogEvent event) {
        return filter(event.getMessage());
    }

    @Override
    public Result filter(final Logger logger, final Level level, final Marker marker, final Message msg,
            final Throwable t) {
        return filter(msg);
    }

    @Override
    public Result filter(final Logger logger, final Level level, final Marker marker, final Object msg,
            final Throwable t) {
        return filter(msg);
    }
}

You can then attach the filter to the appenders, so that it is always applied to a given appender:

appender.csvFile.type = RollingFile
...
appender.csvFile.filter.omaf.type = ObjectArrayMessageFilter
appender.csvFile.filter.omaf.onMatch = ACCEPT
appender.csvFile.filter.omaf.onMismatch = DENY
appender.console.type = Console
...
appender.console.filter.omaf.type = ObjectArrayMessageFilter
appender.console.filter.omaf.onMatch = DENY
appender.console.filter.omaf.onMismatch = ACCEPT

Remark : When developing custom plugins, some standard rules apply: cf. documentation . Basically the plugin's code must be compiled with the annotation processor in log4j-core .