Logback custom appender - minimal example

CustomAppender.java

package utils.logging;

import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.encoder.PatternLayoutEncoder;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.AppenderBase;
import org.slf4j.LoggerFactory;

public class CustomAppender extends AppenderBase<ILoggingEvent> {

    // 1. Fields
    private final Logger rootLogger;
    private final LoggerContext ctx;
    private final PatternLayoutEncoder encoder;

    // 2. Constructor
    private CustomAppender() {
        rootLogger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
        ctx = rootLogger.getLoggerContext();
        encoder = new PatternLayoutEncoder();
    }

    // 3. Initializer
    // Make an appender and register as a logger
    public static void init() {

        // 1. Making instance
        CustomAppender instance = new CustomAppender();

        // 2. Encoder
        instance.encoder.setContext(instance.ctx);
        instance.encoder.setPattern("[%d{yyyy-MM-dd HH:mm:ss}][%thread] ☞ %msg%n");
        instance.encoder.start();

        // 3. Appender
        instance.setContext(instance.ctx);
        instance.start();

        // 4. Apply to log context
        instance.rootLogger.addAppender(instance);

    }

    // 4. Append - main
    @Override
    protected void append(ILoggingEvent event) {
        String msg = new String(encoder.encode(event));
        System.out.println("I got a new log message!: " + msg);
    }

}

Main.java

import lombok.extern.slf4j.Slf4j;

import utils.logging.CustomAppender;

@Slf4j
public class Main {

	public static void main(String[] args) {

		try {

			// Logging start
			CustomAppender.init();

			// Load all preferences
			log.info("Logback custom appender has been applied!");


	}

}