log4j如何设置只保留N天日志呢?
下文笔者讲述log4j设置只保留指定天数日志的方法分享,如下所示
log4j保留指定天数的实现思路:
只需重写的org.apache.log4j.DailyRollingFileAppender源码
即可实现保留指定天数的日志
例:编写相应的实现代码
public class CustomDailyRollingFileAppender extends FileAppender {
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;
/**
* 默认设置："'.'yyyy-MM-dd"
* 设置说明：按天循环打印日志
*/
private String datePattern = "'.'yyyy-MM-dd";
private int maxBackupIndex = 1;
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;
/**
* 获取当前环境所处的时区
* 仅供computeCheckPeriod方法使用
*/
static final TimeZone gmtTimeZone = TimeZone.getTimeZone("GMT");
public CustomDailyRollingFileAppender() {}
public CustomDailyRollingFileAppender(Layout layout, String filename, String datePattern) throws IOException {
super(layout, filename, true);
this.datePattern = datePattern;
activateOptions();
}
public void setDatePattern(String pattern) {
this.datePattern = pattern;
}
public String getDatePattern() {
return datePattern;
}
public int getMaxBackupIndex() {
return maxBackupIndex;
}
public void setMaxBackupIndex(int maxBackupIndex) {
this.maxBackupIndex = maxBackupIndex;
}
/**
* activateOptions译名为激活操作
* 意思是按照配置的参数进行初始化
* scheduledFilename为log的最后一次修改时间
*/
@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+"].");
}
}
/**
* 根据type打印做出日志打印
* @param type
*/
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.getDefault());
//设置初始时间为格林尼治时间：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++) {
//将所示的时间格式化为当前时区
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);
//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...
}
/**
* 按照周期将当前日志文件转存为日期文件
*
* @throws IOException
*/
void rollOver() throws IOException {
if (datePattern == null) {
errorHandler.error("Missing DatePattern option in rollOver().");
return;
}
String datedFilename = fileName+sdf.format(now);
//如果最后一次的修改时间为当前时间 ，则不做任何任何操作
if (scheduledFilename.equals(datedFilename)) {
return;
}
// 关闭当前文件，重命名为日期文件
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);
} else {
LogLog.error("Failed to rename ["+fileName+"] to ["+scheduledFilename+"].");
}
//获取日志文件列表，控制数量，实现清理策略
if (file.getParentFile().exists()){
File[] files = file.getParentFile().listFiles(new LogFileFilter(file.getName()));
Long[] dateArray = new Long[files.length];
for (int i = 0; i < files.length; i++) {
File fileItem = files[i];
String fileDateStr = fileItem.getName().replace(file.getName(), "");
Date filedate = null;
try {
filedate = sdf.parse(fileDateStr);
long fileDateLong = filedate.getTime();
dateArray[i] = fileDateLong;
} catch (ParseException e) {
LogLog.error("Parse File Date Throw Exception : " + e.getMessage());
}
}
Arrays.sort(dateArray);
if (dateArray.length > maxBackupIndex) {
for (int i = 0; i < dateArray.length - maxBackupIndex; i++) {
String dateFileName = file.getPath() + sdf.format(dateArray[i]);
File dateFile = new File(dateFileName);
if (datefile.exists()) {
dateFile.delete();
}
}
}
}
try {
// This will also close the file. This is OK since multiple close operations are safe.
this.setFile(fileName, true, this.bufferedIO, this.bufferSize);
}
catch(IOException e) {
errorHandler.error("setFile("+fileName+", true) call failed.");
}
scheduledFilename = datedFilename;
}
/**
* 写入日志之前判断是否需要新起一个日志来记录
*/
@Override
protected void subAppend(LoggingEvent event) {
long n = System.currentTimeMillis();
if (n >= nextCheck) {
now.setTime(n);
nextCheck = rc.getNextCheckMillis(now);
try {
rollOver();
} catch(IOException ioe) {
if (ioe instanceof InterruptedIOException) {
Thread.currentThread().interrupt();
}
LogLog.error("rollOver() failed.", ioe);
}
}
super.subAppend(event);
}
}
/**
* 文件过滤器
*/
class LogFileFilter implements FileFilter {
private String logName;
public LogFileFilter(String logName) {
this.logName = logName;
}
@Override
public boolean accept(File file) {
if (logName == null || file.isDirectory()) {
return false;
} else {
LogLog.debug(file.getName());
return file.getName().startsWith(logName);
}
}
}
/**
* CustomDailyRollingFileAppender的内部类
* 提供周期类型和当前时间 ，计算并返回下一个周期的开始时间
*/
class RollingCalendar extends GregorianCalendar {
private static final long serialVersionUID = -3560331770601814177L;
int type = CustomDailyRollingFileAppender.TOP_OF_TROUBLE;
/**
* RollingCalendar默认构造器
*/
RollingCalendar() {
super();
}
/**
* RollingCalendar构造器
* 根据地点时区 ，获取对应的日历Calendar
* @param tz
* @param locale
*/
RollingCalendar(TimeZone tz, Locale locale) {
super(tz, locale);
}
void setType(int type) {
this.type = type;
}
public long getNextCheckMillis(Date now) {
return getNextCheckDate(now).getTime();
}
/**
* 根据所传入的时间以及时间类型获取下一个时间
* @param now
* @return
*/
public Date getNextCheckDate(Date now) {
this.setTime(now);
switch(type) {
case CustomDailyRollingFileAppender.TOP_OF_MINUTE:
this.set(Calendar.SECOND, 0);
this.set(Calendar.MILLISECOND, 0);
this.add(Calendar.MINUTE, 1);
break;
case CustomDailyRollingFileAppender.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 CustomDailyRollingFileAppender.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 CustomDailyRollingFileAppender.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 CustomDailyRollingFileAppender.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 CustomDailyRollingFileAppender.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();
}
}
//配置相应的循环周期
log4j.properties文件
log4j.rootLogger=DEBUG,D,consol
log4j.appender.consol=org.apache.log4j.ConsoleAppender
log4j.appender.consol.layout=org.apache.log4j.PatternLayout
log4j.appender.consol.Threshold = debug
log4j.appender.consol.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss} - [ %p ] %m%n
# com.java265.util.CustomDailyRollingFileAppender
# org.apache.log4j.DailyRollingFileAppender
log4j.appender.D = com.java265.util.CustomDailyRollingFileAppender
log4j.appender.D.File =${user.dir}/../logs/ctg_applog_.log
log4j.appender.D.datePattern = yyyy-MM-dd-HH'.'
log4j.appender.D.maxBackupIndex=48
log4j.appender.D.Append = true
log4j.appender.D.Threshold = info
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern =%-d{yyyyMMddHHmmss:S}%m%n
log4j.logger.org.springframework=WARN
log4j.logger.com.ctg=info
log4j.logger.org.apache=WARN
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG
maxBackupIndex就是保留多少个文件,
//我是按照每小时进行生成一个文件
//48 小时则对应4天--保留4天日志
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