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Log4j - Email errors using Gmail

Most of the small projects doesn't have a dedicated person to monitor log file all the times, and its handy to send these errors as email to an email list.

Pros

  1. Never miss an error.
  2. Delete Emails which you want to ignore because of invalid inputs or connectivity issues etc.
  3. Proactively identify bugs and fix them.
  4. Email list is handy i.e. multiple person can receive emails.
  5. If you have different modules in your project and different teams work on them, adding a Labels to your log can by handy since most of the Email Servers can Label emails and redirect them to different folders.
Cons
  1.    Sending email from code takes few seconds, workaround is the create Logger wrapper which logs in a separate thread.

log4j.properties

log4j.rootLogger=ERROR, gmail
log4j.appender.gmail=org.apache.log4j.net.SMTPAppender
log4j.appender.gmail.SMTPProtocol=smtps
log4j.appender.gmail.SMTPUsername=username@gmail.com
log4j.appender.gmail.SMTPPassword=password
log4j.appender.gmail.SMTPHost=smtp.gmail.com
log4j.appender.gmail.SMTPPort=465
log4j.appender.gmail.Subject=Some subject line
log4j.appender.gmail.To=username@gmail.com
log4j.appender.gmail.From=email-list@gmail.com
log4j.appender.gmail.layout=org.apache.log4j.PatternLayout
log4j.appender.gmail.layout.ConversionPattern=%d{MM/dd/yyyy HH:mm:ss}  [%M] %-5p %C - %m%n
log4j.appender.gmail.BufferSize=10


Required Jar files

Activation  download from here

Sample Code

public class Log4jGmailDemo {

    public static void main(String[] args) {
        try {
            int z = 4 / 0;
        } catch (RuntimeException re) {
            logger.error("Module-1", re);
        }
    }
    static Logger logger = Logger.getLogger(Log4jGmailDemo.class);
}

This is only if you are interested using Threads 


public class CustomLogger extends Logger {

    public CustomLogger(String clazz) {
        super(clazz);
    }

    @Override
    public void error(Object message) {
        Runnable runnable = new LoggerRunnable(this, message, null);
        LogExecutor.getInstance().execute(runnable);
    }

    @Override
    public void error(Object message, Throwable throwable) {
        Runnable runnable = new LoggerRunnable(this, message, throwable);
        LogExecutor.getInstance().execute(runnable);
    }

    public static Logger getLogger(Class clazz) {
        return new CustomLogger(clazz.getSimpleName());
    }
}

class LogExecutor {

    private static LogExecutor executor = new LogExecutor();

    private LogExecutor() {
    }
    private ExecutorService service = Executors.newFixedThreadPool(5);

    public static LogExecutor getInstance() {
        return executor;
    }

    public void execute(Runnable runnable) {
        service.execute(runnable);
    }
}

class LoggerRunnable implements Runnable {

    private Logger logger;
    private Object message;
    private Throwable throwable;

    public LoggerRunnable(Logger logger, Object message, Throwable throwable) {
        this.logger = logger;
        this.message = message;
        this.throwable = throwable;
    }

    @Override
    public void run() {
        logger.error(message, throwable);
    }
}

Sample Usage



public class Log4jGmailDemo {

    public static void main(String[] args) {
        try {
            int z = 4 / 0;
        } catch (RuntimeException re) {
            logger.error("Module-1", re);
        }
    }
    static Logger logger = CustomLogger.getLogger(Log4jGmailDemo.class);
}

Comments

Steven said…
Nice article. Just to add: you can use AsyncAppender to make non-blocking emailing of logs instead of writing your own.

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