Java Util Logging - Creating a custom log Handler

This example shows how to Write and register a custom java.util.logging.Handler. A Handler object receives the log messages from a Logger and uses them in any ways it wants. For example, it may write them to a console or write them to a file, or send them to an external logging service etc.

Example

Implementing the Handler

package com.logicbig.example;

import java.util.logging.Handler;
import java.util.logging.LogRecord;

public class MyLogHandler extends Handler {

    @Override
    public void publish(LogRecord record) {
        StringBuilder sb = new StringBuilder();
        sb.append(record.getMillis())
          .append(" - ")
          .append(record.getSourceClassName())
          .append("#")
          .append(record.getSourceMethodName())
          .append(" - ")
          .append(record.getMessage());
        System.out.println(sb.toString());
    }

    @Override
    public void flush() {
    }

    @Override
    public void close() throws SecurityException {
    }
}

Sending log message from application

package com.logicbig.example;

import java.util.logging.Logger;

public class AppClass {
    private static final Logger LOGGER = Logger.getLogger(AppClass.class.getName());

    public void doSomething(){
        LOGGER.info("in AppClass");
    }
}

Registering the custom Handler

We are going to remove all default Handlers and add our custom Handler:

package com.logicbig.example;

import java.util.logging.Handler;
import java.util.logging.LogManager;
import java.util.logging.Logger;

public class ExampleMain {

    public static void main(String[] args) {
        //reset() will remove all default handlers
        LogManager.getLogManager().reset();
        Logger rootLogger = LogManager.getLogManager().getLogger("");

        rootLogger.addHandler(new MyLogHandler());
        AppClass appClass = new AppClass();
        appClass.doSomething();
        rootLogger.info("some message");
    }
}

Output

1761701879212 - com.logicbig.example.AppClass#doSomething - in AppClass
1761701879228 - java.util.logging.LogManager$RootLogger#log - some message

Example Project

Dependencies and Technologies Used:

• JDK 1.8
• Maven 3.3.9