解决log4j不能rename的问题

项目中使用到了log4j包，之前是一天生成一个log文件。之后需要改为一小时生成一个，于是乎，测试的时候发现出现了不能rename的问题，查找原因，发现原来是文件正在被java虚拟机使用。之后就到网上搜了一下，发现大家都出现过这种问题，于是看到了大家的各种解决办法，但都是一种思路，那就是将将文件copy之后再进行rename。具体的做法就是新建一个DailyRollingFileAppender类，当然包名仍然是org.apache.log4j，其具体内容如下：

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.File;
import java.io.InputStream;
import java.io.OutputStream;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Calendar;
import java.util.TimeZone;
import java.util.Locale;

import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;

/**
 * DailyRollingFileAppender extends {@link FileAppender} so that the underlying
 * file is rolled over at a user chosen frequency.
 * 
 * <p>
 * The rolling schedule is specified by the <b>DatePattern</b> option. This
 * pattern should follow the {@link SimpleDateFormat} conventions. In
 * particular, you <em>must</em> escape literal text within a pair of single
 * quotes. A formatted version of the date pattern is used as the suffix for the
 * rolled file name.
 * 
 * <p>
 * For example, if the <b>File</b> option is set to <code>/foo/bar.log</code>
 * and the <b>DatePattern</b> set to <code>'.'yyyy-MM-dd</code>, on
 * 2001-02-16 at midnight, the logging file <code>/foo/bar.log</code> will be
 * copied to <code>/foo/bar.log.2001-02-16</code> and logging for 2001-02-17
 * will continue in <code>/foo/bar.log</code> until it rolls over the next
 * day.
 * 
 * <p>
 * Is is possible to specify monthly, weekly, half-daily, daily, hourly, or
 * minutely rollover schedules.
 * 
 * <p>
 * <table border="1" cellpadding="2">
 * <tr>
 * <th>DatePattern</th>
 * <th>Rollover schedule</th>
 * <th>Example</th>
 * 
 * <tr>
 * <td><code>'.'yyyy-MM</code>
 * <td>Rollover at the beginning of each month</td>
 * 
 * <td>At midnight of May 31st, 2002 <code>/foo/bar.log</code> will be copied
 * to <code>/foo/bar.log.2002-05</code>. Logging for the month of June will
 * be output to <code>/foo/bar.log</code> until it is also rolled over the
 * next month.
 * 
 * <tr>
 * <td><code>'.'yyyy-ww</code>
 * 
 * <td>Rollover at the first day of each week. The first day of the week
 * depends on the locale.</td>
 * 
 * <td>Assuming the first day of the week is Sunday, on Saturday midnight, June
 * 9th 2002, the file <i>/foo/bar.log</i> will be copied to
 * <i>/foo/bar.log.2002-23</i>. Logging for the 24th week of 2002 will be
 * output to <code>/foo/bar.log</code> until it is rolled over the next week.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd</code>
 * 
 * <td>Rollover at midnight each day.</td>
 * 
 * <td>At midnight, on March 8th, 2002, <code>/foo/bar.log</code> will be
 * copied to <code>/foo/bar.log.2002-03-08</code>. Logging for the 9th day of
 * March will be output to <code>/foo/bar.log</code> until it is rolled over
 * the next day.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-a</code>
 * 
 * <td>Rollover at midnight and midday of each day.</td>
 * 
 * <td>At noon, on March 9th, 2002, <code>/foo/bar.log</code> will be copied
 * to <code>/foo/bar.log.2002-03-09-AM</code>. Logging for the afternoon of
 * the 9th will be output to <code>/foo/bar.log</code> until it is rolled over
 * at midnight.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-HH</code>
 * 
 * <td>Rollover at the top of every hour.</td>
 * 
 * <td>At approximately 11:00.000 o'clock on March 9th, 2002,
 * <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2002-03-09-10</code>. Logging for the 11th hour of the
 * 9th of March will be output to <code>/foo/bar.log</code> until it is rolled
 * over at the beginning of the next hour.
 * 
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-HH-mm</code>
 * 
 * <td>Rollover at the beginning of every minute.</td>
 * 
 * <td>At approximately 11:23,000, on March 9th, 2001,
 * <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2001-03-09-10-22</code>. Logging for the minute of
 * 11:23 (9th of March) will be output to <code>/foo/bar.log</code> until it
 * is rolled over the next minute.
 * 
 * </table>
 * 
 * <p>
 * Do not use the colon ":" character in anywhere in the <b>DatePattern</b>
 * option. The text before the colon is interpeted as the protocol specificaion
 * of a URL which is probably not what you want.
 * 
 * 
 * @author Eirik Lygre
 * @author Ceki G&uuml;lc&uuml;
 */
public class DailyRollingFileAppender 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 date pattern. By default, the pattern is set to "'.'yyyy-MM-dd"
     * meaning daily rollover.
     */
    private String datePattern = "'.'yyyy-MM-dd";

    /**
     * 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;

    Date now = new Date();

    SimpleDateFormat sdf;

    RollingCalendar rc = new RollingCalendar();

    int checkPeriod = TOP_OF_TROUBLE;

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

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

    /**
     * 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 DailyRollingFileAppender(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;
    }

    public void activateOptions() {
        super.activateOptions();
        if (datePattern != null && fileName != null) {
            now.setTime(System.currentTimeMillis());
            sdf = new SimpleDateFormat(datePattern);
            int type = computeCheckPeriod();
            printPeriodicity(type);
            rc.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 + "].");
        }
    }

    // This method computes the roll over period by looping over the
    // periods, starting with the shortest, and stopping when the r0 is
    // different from from r1, where r0 is the epoch formatted according
    // the datePattern (supplied by the user) and r1 is the
    // epoch+nextMillis(i) formatted according to datePattern. All date
    // formatting is done in GMT and not local format because the test
    // logic is based on comparisons relative to 1970-01-01 00:00:00
    // GMT (the epoch).

    int computeCheckPeriod() {
        RollingCalendar rollingCalendar = new RollingCalendar(gmtTimeZone,
                Locale.ENGLISH);
        // set sate to 1970-01-01 00:00:00 GMT
        Date epoch = new Date(0);
        if (datePattern != null) {
            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);
                rollingCalendar.setType(i);
                Date next = new Date(rollingCalendar.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 = copy(file, target);
        if (result) {
            LogLog.debug(fileName + " -> " + scheduledFilename);
        } 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;
    }

    /**
     * Copies src file to dst file. If the dst file does not exist, it is
     * created.8KB cache
     * 
     * @param src
     * @param dst
     * @throws IOException
     */
    boolean copy(File src, File dst) throws IOException {
        try {
            InputStream in = new FileInputStream(src);

            OutputStream out = new FileOutputStream(dst);

            // Transfer bytes from in to out
            byte[] buf = new byte[8192];
            int len;
            while ((len = in.read(buf)) > 0) {
                out.write(buf, 0, len);
            }
            in.close();
            out.close();
            return true;
        } catch (FileNotFoundException e) {
            LogLog.error("源文件不存在,或者目标文件无法被识别." + e);
            return false;
        } catch (IOException e) {
            LogLog.error("文件读写错误." + e);
            return false;
        }
    }

    /**
     * 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) {
        long n = System.currentTimeMillis();
        if (n >= nextCheck) {
            now.setTime(n);
            nextCheck = rc.getNextCheckMillis(now);
            try {
                rollOver();
            } catch (IOException ioe) {
                LogLog.error("rollOver() failed.", ioe);
            }
        }
        super.subAppend(event);
    }
}

/**
 * RollingCalendar is a helper class to DailyRollingFileAppender. Given a
 * periodicity type and the current time, it computes the start of the next
 * interval.
 */
class RollingCalendar extends GregorianCalendar {
    private static final long serialVersionUID = -3560331770601814177L;

    int type = DailyRollingFileAppender.TOP_OF_TROUBLE;

    RollingCalendar() {
        super();
    }

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

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

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

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

        switch (type) {
        case DailyRollingFileAppender.TOP_OF_MINUTE:
            this.set(Calendar.SECOND, 0);
            this.set(Calendar.MILLISECOND, 0);
            this.add(Calendar.MINUTE, 1);
            break;
        case DailyRollingFileAppender.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 DailyRollingFileAppender.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 DailyRollingFileAppender.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 DailyRollingFileAppender.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 DailyRollingFileAppender.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();
    }
}

之后就可以啦！当然还有一种方案就是将原文件中的该类修改之后重新打包，把原来的包替换为修改之后的就OK了。