如何让log4j删除旧的旋转日志文件？我知道我可以设置自动化作业（UNIX的cron和Windows的计划任务），但我希望它跨平台，我希望它在我们的应用程序的日志配置中作为我们的应用程序的一部分，而不是在OS之外的单独代码中特定的脚本语言。我们的应用程序不是用OS脚本语言编写的，我不想在其中使用它。
答案 0 :(得分：49)
RollingFileAppender执行此操作。您只需将maxBackupIndex设置为备份文件的最高值。
答案 1 :(得分：39)
日志轮换有一个原因，因此您只能保留这么多日志文件。在log4j.xml中，您可以将其添加到您的节点：
<param name="MaxBackupIndex" value="20"/>
该值告诉log4j.xml只保留20个旋转的日志文件。如果你想要甚至1，你可以将其限制为5.如果你的应用程序没有记录那么多数据，并且你有20个日志文件跨越过去8个月，但你只需要一周的日志，那么我认为你需要调整你的log4j.xml“MaxBackupIndex”和“MaxFileSize”参数。
或者，如果您使用属性文件（而不是xml）并希望保存15个文件（例如）
log4j.appender.[appenderName].MaxBackupIndex = 15
答案 2 :(得分：8)
没有默认值来控制删除DailyRollingFileAppender创建的旧日志文件。但您可以编写自己的自定义Appender来删除旧的日志文件，其方式与为RollingFileAppender设置maxBackupIndex的方式非常相似。
发现简单说明here
来自1：
如果您尝试将Apache Log4J DailyRollingFileAppender用于日常日志文件，则可能需要指定应保留的最大文件数。就像滚动RollingFileAppender支持maxBackupIndex一样。但是，如果您使用DailyRollingFileAppender，则当前版本的Log4j（Apache log4j 1.2.16）不提供删除旧日志文件的任何机制。我试图在DailyRollingFileAppender的原始版本中进行小的修改以添加maxBackupIndex属性。因此，可以清理旧日志文件，这些日志文件可能不需要将来使用。
答案 3 :(得分：0)
您可以使用自定义log4j附加程序来实现。
MaxNumberOfDays -可以设置轮换日志文件的天数。
CompressBackups -可以存档带有zip扩展名的旧日志。
package com.example.package;
import org.apache.log4j.FileAppender;
import org.apache.log4j.Layout;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.Optional;
import java.util.TimeZone;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
public class CustomLog4jAppender extends FileAppender {
private static final int TOP_OF_TROUBLE = -1;
private static final int TOP_OF_MINUTE = 0;
private static final int TOP_OF_HOUR = 1;
private static final int HALF_DAY = 2;
private static final int TOP_OF_DAY = 3;
private static final int TOP_OF_WEEK = 4;
private static final int TOP_OF_MONTH = 5;
private String datePattern = "'.'yyyy-MM-dd";
private String compressBackups = "false";
private String maxNumberOfDays = "7";
private String scheduledFilename;
private long nextCheck = System.currentTimeMillis() - 1;
private Date now = new Date();
private SimpleDateFormat sdf;
private RollingCalendar rc = new RollingCalendar();
private static final TimeZone gmtTimeZone = TimeZone.getTimeZone("GMT");
public CustomLog4jAppender() {
}
public CustomLog4jAppender(Layout layout, String filename, String datePattern) throws IOException {
super(layout, filename, true);
this.datePattern = datePattern;
activateOptions();
}
public void setDatePattern(String pattern) {
datePattern = pattern;
}
public String getDatePattern() {
return datePattern;
}
@Override
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 + "].");
}
}
private void printPeriodicity(int type) {
String appender = "Log4J Appender: ";
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 + "].");
}
}
private int computeCheckPeriod() {
RollingCalendar rollingCalendar = new RollingCalendar(gmtTimeZone, Locale.ENGLISH);
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);
String r0 = simpleDateFormat.format(epoch);
rollingCalendar.setType(i);
Date next = new Date(rollingCalendar.getNextCheckMillis(epoch));
String r1 = simpleDateFormat.format(next);
if (!r0.equals(r1)) {
return i;
}
}
}
return TOP_OF_TROUBLE;
}
private void rollOver() throws IOException {
if (datePattern == null) {
errorHandler.error("Missing DatePattern option in rollOver().");
return;
}
String datedFilename = fileName + sdf.format(now);
if (scheduledFilename.equals(datedFilename)) {
return;
}
this.closeFile();
File target = new File(scheduledFilename);
if (target.exists()) {
Files.delete(target.toPath());
}
File file = new File(fileName);
boolean result = file.renameTo(target);
if (result) {
LogLog.debug(fileName + " -> " + scheduledFilename);
} else {
LogLog.error("Failed to rename [" + fileName + "] to [" + scheduledFilename + "].");
}
try {
this.setFile(fileName, false, this.bufferedIO, this.bufferSize);
} catch (IOException e) {
errorHandler.error("setFile(" + fileName + ", false) call failed.");
}
scheduledFilename = datedFilename;
}
@Override
protected void subAppend(LoggingEvent event) {
long n = System.currentTimeMillis();
if (n >= nextCheck) {
now.setTime(n);
nextCheck = rc.getNextCheckMillis(now);
try {
cleanupAndRollOver();
} catch (IOException ioe) {
LogLog.error("cleanupAndRollover() failed.", ioe);
}
}
super.subAppend(event);
}
public String getCompressBackups() {
return compressBackups;
}
public void setCompressBackups(String compressBackups) {
this.compressBackups = compressBackups;
}
public String getMaxNumberOfDays() {
return maxNumberOfDays;
}
public void setMaxNumberOfDays(String maxNumberOfDays) {
this.maxNumberOfDays = maxNumberOfDays;
}
protected void cleanupAndRollOver() throws IOException {
File file = new File(fileName);
Calendar cal = Calendar.getInstance();
int maxDays = 7;
try {
maxDays = Integer.parseInt(getMaxNumberOfDays());
} catch (Exception e) {
// just leave it at 7.
}
cal.add(Calendar.DATE, -maxDays);
Date cutoffDate = cal.getTime();
if (file.getParentFile().exists()) {
File[] files = file.getParentFile().listFiles(new StartsWithFileFilter(file.getName(), false));
int nameLength = file.getName().length();
for (File value : Optional.ofNullable(files).orElse(new File[0])) {
String datePart;
try {
datePart = value.getName().substring(nameLength);
Date date = sdf.parse(datePart);
if (date.before(cutoffDate)) {
Files.delete(value.toPath());
} else if (getCompressBackups().equalsIgnoreCase("YES") || getCompressBackups().equalsIgnoreCase("TRUE")) {
zipAndDelete(value);
}
} catch (Exception pe) {
// This isn't a file we should touch (it isn't named correctly)
}
}
}
rollOver();
}
private void zipAndDelete(File file) throws IOException {
if (!file.getName().endsWith(".zip")) {
File zipFile = new File(file.getParent(), file.getName() + ".zip");
try (FileInputStream fis = new FileInputStream(file);
FileOutputStream fos = new FileOutputStream(zipFile);
ZipOutputStream zos = new ZipOutputStream(fos)) {
ZipEntry zipEntry = new ZipEntry(file.getName());
zos.putNextEntry(zipEntry);
byte[] buffer = new byte[4096];
while (true) {
int bytesRead = fis.read(buffer);
if (bytesRead == -1) {
break;
} else {
zos.write(buffer, 0, bytesRead);
}
}
zos.closeEntry();
}
Files.delete(file.toPath());
}
}
class StartsWithFileFilter implements FileFilter {
private String startsWith;
private boolean inclDirs;
StartsWithFileFilter(String startsWith, boolean includeDirectories) {
super();
this.startsWith = startsWith.toUpperCase();
inclDirs = includeDirectories;
}
public boolean accept(File pathname) {
if (!inclDirs && pathname.isDirectory()) {
return false;
} else {
return pathname.getName().toUpperCase().startsWith(startsWith);
}
}
}
class RollingCalendar extends GregorianCalendar {
private static final long serialVersionUID = -3560331770601814177L;
int type = CustomLog4jAppender.TOP_OF_TROUBLE;
RollingCalendar() {
super();
}
RollingCalendar(TimeZone tz, Locale locale) {
super(tz, locale);
}
void setType(int type) {
this.type = type;
}
long getNextCheckMillis(Date now) {
return getNextCheckDate(now).getTime();
}
Date getNextCheckDate(Date now) {
this.setTime(now);
switch (type) {
case CustomLog4jAppender.TOP_OF_MINUTE:
this.set(Calendar.SECOND, 0);
this.set(Calendar.MILLISECOND, 0);
this.add(Calendar.MINUTE, 1);
break;
case CustomLog4jAppender.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 CustomLog4jAppender.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 CustomLog4jAppender.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 CustomLog4jAppender.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 CustomLog4jAppender.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();
}
}
}
并在log4j配置文件中使用以下属性：
log4j.appender.[appenderName]=com.example.package.CustomLog4jAppender
log4j.appender.[appenderName].File=/logs/app-daily.log
log4j.appender.[appenderName].Append=true
log4j.appender.[appenderName].encoding=UTF-8
log4j.appender.[appenderName].layout=org.apache.log4j.EnhancedPatternLayout
log4j.appender.[appenderName].layout.ConversionPattern=%-5.5p %d %C{1.} - %m%n
log4j.appender.[appenderName].DatePattern='.'yyyy-MM-dd
log4j.appender.[appenderName].MaxNumberOfDays=7
log4j.appender.[appenderName].CompressBackups=true