log4j DailyRollingFileAppender支持保留最近n天，并且可以对一天的文件根据大小切分_JAVA_编程开发_程序员俱乐部

log4j DailyRollingFileAppender不支持只保留最近n天的数据，时间一久导致日志文件很多，并且一天的文件有可能比较大，所以自己写了个appender，以解决这两个问题。

??? 具体代码实现如下：

class="java" name="code">package com.mytools.common.log4jext;

import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import java.io.Writer;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.TimeZone;

import org.apache.log4j.FileAppender;
import org.apache.log4j.Layout;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.apache.log4j.PatternLayout;
import org.apache.log4j.helpers.CountingQuietWriter;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;

/**
 * log4j appender扩展<br>
 * （1）按天并且只保留最近n天的 <br>
 * （2）如果一天的文件过大，可以按配置的大小将一天的文件进行切分
 * 

 * @since 2016-6-13
 */
public class MyDailyRollingFileAppender extends FileAppender
{

	// The code assumes that the following constants are in a increasing
	// sequence.
	static final int TOP_OF_TROUBLE = -1;
	static final int TOP_OF_MINUTE = 0;
	static final int TOP_OF_HOUR = 1;
	static final int HALF_DAY = 2;
	static final int TOP_OF_DAY = 3;
	static final int TOP_OF_WEEK = 4;
	static final int TOP_OF_MONTH = 5;

	/**
	 * The gmtTimeZone is used only in computeCheckPeriod() method.
	 */
	public static final TimeZone gmtTimeZone = TimeZone.getTimeZone("GMT");

	/**
	 * The default maximum file size is 10MB. , 10K for test
	 */
	protected long maxFileSize = 10 * 1024;

	/**
	 * The date pattern. By default, the pattern is set to "'.'yyyy-MM-dd" meaning daily
	 * rollover.
	 */
	private String datePattern = "'.'yyyy-MM-dd";

	/**
	 * There is one backup file by default.
	 */
	private int maxBackupIndex = 1;

	/**
	 * The log file will be renamed to the value of the scheduledFilename variable when
	 * the next interval is entered. For example, if the rollover period is one hour, the
	 * log file will be renamed to the value of "scheduledFilename" at the beginning of
	 * the next hour. The precise time when a rollover occurs depends on logging activity.
	 */
	private String scheduledFilename;

	/**
	 * The next time we estimate a rollover should occur.
	 */
	private long nextCheck = System.currentTimeMillis() - 1;

	private Date now = new Date();

	private SimpleDateFormat sdf;

	private MyRollingCalendar rollingCalendar = new MyRollingCalendar();

	public int checkPeriod = TOP_OF_TROUBLE;

	/**
	 * The default constructor does nothing.
	 */
	public MyDailyRollingFileAppender()
	{
	}

	/**
	 * Instantiate a <code>DailyRollingFileAppender</code> and open the file designated by
	 * <code>filename</code>. The opened filename will become the ouput destination for
	 * this appender.
	 */
	public MyDailyRollingFileAppender(Layout layout, String filename, String datePattern) throws IOException
	{
		super(layout, filename, true);
		this.datePattern = datePattern;
		activateOptions();
	}

	/**
	 * The <b>DatePattern</b> takes a string in the same format as expected by
	 * {@link SimpleDateFormat}. This options determines the rollover schedule.
	 */
	public void setDatePattern(String pattern)
	{
		datePattern = pattern;
	}

	/** Returns the value of the <b>DatePattern</b> option. */
	public String getDatePattern()
	{
		return datePattern;
	}

	/**
	 * 设置日志文件最大备份数
	 * <p>
	 * The <b>MaxBackupIndex</b> option determines how many backup files are kept before
	 * the oldest is erased. This option takes a positive integer value. If set to zero,
	 * then there will be no backup files and the log file will be renamed to the value of
	 * the scheduledFilename variable when the next interval is entered.
	 */
	public void setMaxBackupIndex(int maxBackups)
	{
		this.maxBackupIndex = maxBackups;
	}

	/**
	 * 返回日志文件最大备份数
	 */
	public int getMaxBackupIndex()
	{
		return maxBackupIndex;
	}

	public void activateOptions()
	{
		super.activateOptions();

		LogLog.debug("Max backup file kept: " + maxBackupIndex + ".");

		if (datePattern != null && fileName != null)
		{
			now.setTime(System.currentTimeMillis());
			sdf = new SimpleDateFormat(datePattern);
			int type = computeCheckPeriod();
			printPeriodicity(type);
			rollingCalendar.setType(type);
			File file = new File(fileName);
			scheduledFilename = fileName + sdf.format(new Date(file.lastModified()));
		}
		else
		{
			LogLog.error("Either File or DatePattern options are not set for appender [" + name + "].");
		}
	}

	void printPeriodicity(int type)
	{
		switch (type)
		{
			case TOP_OF_MINUTE:
				LogLog.debug("Appender [[+name+]] to be rolled every minute.");
				break;
			case TOP_OF_HOUR:
				LogLog.debug("Appender [" + name + "] to be rolled on top of every hour.");
				break;
			case HALF_DAY:
				LogLog.debug("Appender [" + name + "] to be rolled at midday and midnight.");
				break;
			case TOP_OF_DAY:
				LogLog.debug("Appender [" + name + "] to be rolled at midnight.");
				break;
			case TOP_OF_WEEK:
				LogLog.debug("Appender [" + name + "] to be rolled at start of week.");
				break;
			case TOP_OF_MONTH:
				LogLog.debug("Appender [" + name + "] to be rolled at start of every month.");
				break;
			default:
				LogLog.warn("Unknown periodicity for appender [[+name+]].");
		}
	}

	int computeCheckPeriod()
	{
		MyRollingCalendar rollingPastCalendar = new MyRollingCalendar(gmtTimeZone, Locale.ENGLISH);
		// set sate to 1970-01-01 00:00:00 GMT
		Date epoch = new Date(0);

		if (datePattern == null)
		{
			return TOP_OF_TROUBLE;
		}

		for (int i = TOP_OF_MINUTE; i <= TOP_OF_MONTH; i++)
		{
			SimpleDateFormat simpleDateFormat = new SimpleDateFormat(datePattern);
			simpleDateFormat.setTimeZone(gmtTimeZone); // do all date formatting in
														// GMT
			String r0 = simpleDateFormat.format(epoch);
			rollingPastCalendar.setType(i);
			Date next = new Date(rollingPastCalendar.getNextCheckMillis(epoch));
			String r1 = simpleDateFormat.format(next);

			// System.out.println("Type = "+i+", r0 = "+r0+", r1 = "+r1);
			if (r0 != null && r1 != null && !r0.equals(r1))
			{
				return i;
			}
		}

		return TOP_OF_TROUBLE; // Deliberately head for trouble...
	}

	/**
	 * Rollover the current file to a new file.
	 */
	void rollOver() throws IOException
	{
		/* Compute filename, but only if datePattern is specified */
		if (datePattern == null)
		{
			errorHandler.error("Missing DatePattern option in rollOver().");
			return;
		}

		String datedFilename = fileName + sdf.format(now);
		// It is too early to roll over because we are still within the
		// bounds of the current interval. Rollover will occur once the
		// next interval is reached.
		if (scheduledFilename.equals(datedFilename))
		{
			return;
		}

		// close current file, and rename it to datedFilename
		this.closeFile();

		File target = new File(scheduledFilename);
		if (target.exists())
		{
			target.delete();
		}

		File file = new File(fileName);
		boolean result = file.renameTo(target);
		if (result)
		{
			LogLog.debug(fileName + " -> " + scheduledFilename);

			// If maxBackups <= 0, then there is no file renaming to be done.
			if (maxBackupIndex > 0)
			{
				// Delete the oldest file, to keep system happy.
				file = new File(fileName + dateBefore());

				// 删除很久以前的历史log文件
				deleteAncientFilesIfExists(file);

				if (file.exists())
				{
					file.delete();
				}
			}
		}
		else
		{
			LogLog.error("Failed to rename [[+fileName+]] to [[+scheduledFilename+]].");
		}

		try
		{
			// This will also close the file. This is OK since multiple close operations
			// are safe.
			this.setFile(fileName, false, this.bufferedIO, this.bufferSize);
		}
		catch (IOException e)
		{
			errorHandler.error("setFile(" + fileName + ", false) call failed.");
		}

		scheduledFilename = datedFilename;
	}

	/**
	 * 删除很久以前没有删除的日志文件（如果存在的话）
	 * 
	 * @param oldestFile
	 */
	private void deleteAncientFilesIfExists(final File oldestFile)
	{
		// 找出久远日志文件列表
		File[] ancientfiles = oldestFile.getParentFile().listFiles(new FileFilter()
		{

			@Override
			public boolean accept(File pathname)
			{
				if (pathname.getPath().replaceAll("\\\\", "/").startsWith(fileName.replaceAll("\\\\", "/"))
						&& pathname.getName().compareTo(oldestFile.getName()) < 0)
				{
					return true;
				}
				else
				{
					return false;
				}
			}
		});

		// 删除久远日志文件列表
		for (File ancientfile : ancientfiles)
		{
			// 如果文件比配置的最老日期还老的话，删掉
			ancientfile.delete();
		}
	}

	private String dateBefore()
	{
		String dataAnte = "";

		if (datePattern != null)
		{
			SimpleDateFormat simpleDateFormat = new SimpleDateFormat(datePattern);

			dataAnte = simpleDateFormat
					.format(new Date(rollingCalendar.getPastCheckMillis(new Date(), maxBackupIndex)));
		}

		return dataAnte;
	}

	/**
	 * This method differentiates DailyRollingFileAppender from its super class.
	 * <p>
	 * Before actually logging, this method will check whether it is time to do a
	 * rollover. If it is, it will schedule the next rollover time and then rollover.
	 */
	protected void subAppend(LoggingEvent event)
	{
		// 根据文件大小roll over
		rollOverBySize();

		// 根据时间roll over
		rollOverByTime();

		super.subAppend(event);
	}

	/**
	 * 根据文件大小roll over
	 */
	private void rollOverBySize()
	{
		long currentTimeMillis = System.currentTimeMillis();
		now.setTime(currentTimeMillis);

		if (fileName != null && qw != null)
		{
			long size = ((CountingQuietWriter) qw).getCount();
			if (size >= maxFileSize)
			{
				// close current file, and rename it
				this.closeFile();

				String rollingFileName = fileName + sdf.format(now) + '.' + currentTimeMillis;
				new File(fileName).renameTo(new File(rollingFileName));

				try
				{
					// This will also close the file. This is OK since multiple close
					// operations
					// are safe.
					this.setFile(fileName, false, this.bufferedIO, this.bufferSize);
				}
				catch (IOException e)
				{
					errorHandler.error("setFile(" + fileName + ", false) call failed.");
				}
			}
		}
	}

	/**
	 * 根据时间roll over
	 */
	private void rollOverByTime()
	{
		long currentTime = System.currentTimeMillis();

		if (currentTime < nextCheck)
		{
			return;
		}

		now.setTime(currentTime);
		nextCheck = rollingCalendar.getNextCheckMillis(now);

		try
		{
			rollOver();
		}
		catch (IOException ioe)
		{
			LogLog.error("rollOver() failed.", ioe);
		}
	}

	@Override
	public synchronized void setFile(String fileName, boolean append, boolean bufferedIO, int bufferSize)
			throws IOException
	{
		super.setFile(fileName, append, this.bufferedIO, this.bufferSize);
		if (append)
		{
			File f = new File(fileName);
			((CountingQuietWriter) qw).setCount(f.length());
		}
	}

	@Override
	protected void setQWForFiles(Writer writer)
	{
		this.qw = new CountingQuietWriter(writer, errorHandler);
	}

	/**
	 * 测试方法
	 */
	public static void main(String args[])
	{
		String className = MyDailyRollingFileAppender.class.getName();

		MyDailyRollingFileAppender myAppender = new MyDailyRollingFileAppender();

		myAppender.setDatePattern("'.'yyyy-MM-dd-HH");
		myAppender.setFile("E:/test/mylogApender/prova.log");
		myAppender.setMaxBackupIndex(3);

		PatternLayout patternLayout = new PatternLayout("%d [%-5p]-[%t]-[%c{1}] (%F:%L) %m%n");
		myAppender.setLayout(patternLayout);

		System.out.println("dmrfa.getMaxBackupIndex():" + myAppender.getMaxBackupIndex());

		myAppender.activateOptions();

		for (int i = 0; i < 50000; i++)
		{
			myAppender.subAppend(new LoggingEvent(className, Logger.getLogger(className), Level.INFO,
					"test,hello " + i, null));

			try
			{
				Thread.sleep(100);
			}
			catch (InterruptedException ex)
			{
				ex.printStackTrace();
			}

			System.out.println("Fine attesa");
		}
	}
}

/**
 * MyRollingCalendar is a helper class to DailyMaxRollingFileAppender. Given a periodicity
 * type and the current time, it computes the past maxBackupIndex date.
 */
class MyRollingCalendar extends GregorianCalendar
{

	private static final long serialVersionUID = 1L;

	public static final int TOP_OF_TROUBLE = -1;
	public static final int TOP_OF_MINUTE = 0;
	public static final int TOP_OF_HOUR = 1;
	public static final int HALF_DAY = 2;
	public static final int TOP_OF_DAY = 3;
	public static final int TOP_OF_WEEK = 4;
	public static final int TOP_OF_MONTH = 5;

	int type = TOP_OF_TROUBLE;

	MyRollingCalendar()
	{
		super();
	}

	MyRollingCalendar(TimeZone tz, Locale locale)
	{
		super(tz, locale);
	}

	public long getPastCheckMillis(Date now, int maxBackupIndex)
	{
		return getPastDate(now, maxBackupIndex).getTime();
	}

	public Date getPastDate(Date now, int maxBackupIndex)
	{
		this.setTime(now);

		switch (type)
		{
			case TOP_OF_MINUTE:
				this.set(Calendar.MINUTE, this.get(Calendar.MINUTE) - maxBackupIndex);
				break;

			case TOP_OF_HOUR:
				this.set(Calendar.HOUR_OF_DAY, this.get(Calendar.HOUR_OF_DAY) - maxBackupIndex);
				break;

			case HALF_DAY:
				int hour = get(Calendar.HOUR_OF_DAY);
				if (hour < 12)
				{
					this.set(Calendar.HOUR_OF_DAY, 12);
				}
				else
				{
					this.set(Calendar.HOUR_OF_DAY, 0);
				}
				this.set(Calendar.DAY_OF_MONTH, this.get(Calendar.DAY_OF_MONTH) - maxBackupIndex);
				break;

			case TOP_OF_DAY:
				this.set(Calendar.DATE, this.get(Calendar.DATE) - maxBackupIndex);
				break;

			case TOP_OF_WEEK:
				this.set(Calendar.DAY_OF_WEEK, getFirstDayOfWeek());
				this.set(Calendar.WEEK_OF_YEAR, this.get(Calendar.WEEK_OF_YEAR) - maxBackupIndex);
				break;

			case TOP_OF_MONTH:
				this.set(Calendar.MONTH, this.get(Calendar.MONTH) - maxBackupIndex);
				break;

			default:
				throw new IllegalStateException("Unknown periodicity type.");
		}

		return this.getTime();
	}

	public long getNextCheckMillis(Date now)
	{
		return getNextCheckDate(now).getTime();
	}

	public Date getNextCheckDate(Date now)
	{
		this.setTime(now);

		switch (type)
		{
			case TOP_OF_MINUTE:
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				this.add(Calendar.MINUTE, 1);
				break;
			case TOP_OF_HOUR:
				this.set(Calendar.MINUTE, 0);
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				this.add(Calendar.HOUR_OF_DAY, 1);
				break;
			case HALF_DAY:
				this.set(Calendar.MINUTE, 0);
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				int hour = get(Calendar.HOUR_OF_DAY);
				if (hour < 12)
				{
					this.set(Calendar.HOUR_OF_DAY, 12);
				}
				else
				{
					this.set(Calendar.HOUR_OF_DAY, 0);
					this.add(Calendar.DAY_OF_MONTH, 1);
				}
				break;
			case TOP_OF_DAY:
				this.set(Calendar.HOUR_OF_DAY, 0);
				this.set(Calendar.MINUTE, 0);
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				this.add(Calendar.DATE, 1);
				break;
			case TOP_OF_WEEK:
				this.set(Calendar.DAY_OF_WEEK, getFirstDayOfWeek());
				this.set(Calendar.HOUR_OF_DAY, 0);
				this.set(Calendar.MINUTE, 0);
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				this.add(Calendar.WEEK_OF_YEAR, 1);
				break;
			case TOP_OF_MONTH:
				this.set(Calendar.DATE, 1);
				this.set(Calendar.HOUR_OF_DAY, 0);
				this.set(Calendar.MINUTE, 0);
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				this.add(Calendar.MONTH, 1);
				break;
			default:
				throw new IllegalStateException("Unknown periodicity type.");
		}
		return getTime();
	}

	void setType(int type)
	{
		this.type = type;
	}
}

?使用时在appender配置的地方增加MaxBackupIndex配置即可。