SimpleLogger Java

SimpleLogFormatter.java

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

/**
 * 
 * Formatter for simple logs.
 * 
 * @author unlucky0314
 *
 */
public class SimpleLogFormatter extends Formatter
{
	private SimpleDateFormat dateFormat = null;
	
	@Override
	public String format(LogRecord record)
	{
		if(dateFormat == null)
		{
			dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
		}
		final String msg = formatMessage(record);
		
		return "%s [ %s ] : %s%n".formatted(
				dateFormat.format(Date.from(record.getInstant())), center(record.getLevel().getName(), 7), msg);
	}
	
	/**
	 * Aligns the string centered within the size range.
	 * 
	 * @param s string.
	 * @param size range.
	 * @return result
	 */
	private static String center(String s, int size)
	{
		return center(s, size, ' ');
	}
	
	/**
	 * Aligns the string centered within the size range.
	 * 
	 * @param s string.
	 * @param size range.
	 * @return result
	 */
	private static String center(String s, int size, char pad)
	{
		if(s == null || size <= s.length())
		{
			return s;
		}
		
		StringBuilder builder = new StringBuilder(size);
		for(int i = 0; i < (size - s.length()) / 2; i++)
		{
			builder.append(pad);
		}
		builder.append(s);
		while(builder.length() < size)
		{
			builder.append(pad);
		}
		return builder.toString();
	}
}

SimpleLogger.java

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.logging.Level;

/**
 * 
 * It is a logger that can export simple logs.
 * 
 * @author unlucky0314
 *
 */
public class SimpleLogger
{
	private static String logFilePath = null;
	private static SimpleDateFormat dateFormat = null;
	
	PrintWriter writer = null;
	
	/**
	 * 
	 * constructor.
	 * 
	 * @param logFileDirectory Set the directory where log files are generated.<br>
	 *                          example "aaa/bbb/"
	 * @throws IOException
	 */
	public SimpleLogger(String logFileDirectory)
	{
		try
		{
			Date date = new Date();
			if (dateFormat == null)
			{
				dateFormat =  new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
			}
			_directoryExistCheck(logFileDirectory);
		
			SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd_HHmmss");
			logFilePath = logFileDirectory + "Log" + format.format(date) + ".log";
		
			writer = new PrintWriter(logFilePath, "UTF-8");
		}
		catch (IOException e)
		{
			writer.close();
			e.printStackTrace();
		}
	}
	
	/**
	 * Aligns the string centered within the size range.
	 * 
	 * @param s string.
	 * @param size range.
	 * @return result
	 */
	private static String center(String s, int size)
	{
		return center(s, size, ' ');
	}
	
	/**
	 * Aligns the string centered within the size range.
	 * 
	 * @param s string.
	 * @param size range.
	 * @return result
	 */
	private static String center(String s, int size, char pad)
	{
		if(s == null || size <= s.length())
		{
			return s;
		}
		
		StringBuilder builder = new StringBuilder(size);
		for(int i = 0; i < (size - s.length()) / 2; i++)
		{
			builder.append(pad);
		}
		builder.append(s);
		while(builder.length() < size)
		{
			builder.append(pad);
		}
		return builder.toString();
	}
	
	/**
	 * 
	 * @param directoryPath
	 */
	private void _directoryExistCheck(String directoryPath) throws IOException
	{
		File file = new File(directoryPath);
		if(!file.exists())
		{
			Path path = Paths.get(directoryPath);
			Files.createDirectories(path);
		}
	}
	
	public void close()
	{
		if(writer != null)
		{
			writer.close();
			writer = null;
		}
	}
	
	/**
	 * Log a message, with no arguments.
	 * 
	 * @param level Log level.
	 * @param message Log message.
	 */
	public void log(String level, String message)
	{
		Date date = new Date();
		String result = "%s [ %s ] : %s".formatted(
				dateFormat.format(date), center(level, 9), message);
		System.out.println(result);
		writer.println(result);
	}
	
	/**
	 * Log a message, with no arguments.
	 * 
	 * @param level Log level.
	 * @param message Log message.
	 */
	public void log(Level level, String message)
	{
		this.log(level.getName(), message);
	}
	
	/**
	 * Log an information message.
	 * 
	 * @param message
	 */
	public void info(String message)
	{
		this.log(Level.INFO, message);
	}
	
	/**
	 * Log a warning message.
	 * 
	 * @param message
	 */
	public void warning(String message)
	{
		this.log(Level.WARNING, message);
	}
	
	/**
	 * Log an error message.
	 * 
	 * @param message
	 */
	public void error(String message)
	{
		this.log("ERROR", message);
	}
	
	/**
	 * Log an exception message.
	 * 
	 * @param message
	 * @param e
	 */
	public void exception(String message, Exception e)
	{
		this.log("EXCEPTION", message + ":\n" + e);
	}
	
	@Override
	public void finalize()
	{
		close();
	}
}

SingletonSimpleLogger.java

public class SingletonSimpleLogger
{
	private static SingletonSimpleLogger _instance = null;
	
	private SimpleLogger logger = null;
	
	private SingletonSimpleLogger(String logFileDirectory)
	{
		logger = new SimpleLogger(logFileDirectory);
	}
	
	public static void Initialize(String logFileDirectory)
	{
		if(_instance == null)
		{
			_instance = new SingletonSimpleLogger(logFileDirectory);
		}
	}
	
	public static void Finalize()
	{
		if(_instance != null)
		{
			_instance.finalize();
			_instance = null;
		}
	}
	
	public static SingletonSimpleLogger getInstance() throws NullPointerException
	{
		if(_instance == null)
		{
			throw new NullPointerException();
		}
		return _instance;
	}
	
	public SimpleLogger getLogger()
	{
		if(logger == null)
		{
			throw new NullPointerException("Initialize is not called.");
		}
		return logger;
	}
	
	@Override
	public void finalize()
	{
		if(logger != null)
		{
			logger.close();
			logger = null;
		}
	}
}