Java Logger: Have a different output color for each severity level

Question

With the following code from this stack question: Change color and format of java.util.logging.Logger output in Eclipse

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.logging.Formatter;
import java.util.logging.LogRecord;

public class LogFormatter extends Formatter
{
    // ANSI escape code
    public static final String ANSI_RESET = "\u001B[0m";
    public static final String ANSI_BLACK = "\u001B[30m";
    public static final String ANSI_RED = "\u001B[31m";
    public static final String ANSI_GREEN = "\u001B[32m";
    public static final String ANSI_YELLOW = "\u001B[33m";
    public static final String ANSI_BLUE = "\u001B[34m";
    public static final String ANSI_PURPLE = "\u001B[35m";
    public static final String ANSI_CYAN = "\u001B[36m";
    public static final String ANSI_WHITE = "\u001B[37m";

    // Here you can configure the format of the output and 
    // its color by using the ANSI escape codes defined above.

    // format is called for every console log message
    @Override
    public String format(LogRecord record)
    {
        // This example will print date/time, class, and log level in yellow,
        // followed by the log message and it's parameters in white .
        StringBuilder builder = new StringBuilder();
        builder.append(ANSI_YELLOW);

        builder.append("[");
        builder.append(calcDate(record.getMillis()));
        builder.append("]");

        builder.append(" [");
        builder.append(record.getSourceClassName());
        builder.append("]");

        builder.append(" [");
        builder.append(record.getLevel().getName());
        builder.append("]");

        builder.append(ANSI_WHITE);
        builder.append(" - ");
        builder.append(record.getMessage());

        Object[] params = record.getParameters();

        if (params != null)
        {
            builder.append("\t");
            for (int i = 0; i < params.length; i++)
            {
                builder.append(params[i]);
                if (i < params.length - 1)
                    builder.append(", ");
            }
        }

        builder.append(ANSI_RESET);
        builder.append("\n");
        return builder.toString();
    }

    private String calcDate(long millisecs) {
        SimpleDateFormat date_format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Date resultdate = new Date(millisecs);
        return date_format.format(resultdate);
    }
}

I can have log file with colors:

However, I would like to have a different color if the log severity is either warning, severe or info. Is there a way to do that without creating one Logger object per severity?

score 3 · Accepted Answer · answered Oct 01 '19 at 10:03

I think you can check the log level on the LogRecord, and use a different ansi code based on the level in the format method:

@Override
public String format(LogRecord record)
{
    StringBuilder builder = new StringBuilder();

    Level level = record.getLevel();
    if(level == Level.INFO) {
      builder.append(ANSI_GREEN);
    } else if(level == Level.WARNING) {
      builder.append(ANSI_YELLOW);
    } else if(level == Level.SEVERE) {
      builder.append(ANSI_RED);
    } else {
      builder.append(ANSI_WHITE);
    }

    builder.append("[");
    builder.append(calcDate(record.getMillis()));
    builder.append("]");

    ...

}

Java Logger: Have a different output color for each severity level

1 Answers1