log4j按照日期或时间格式生成备份日志文件
1.写在前面：
log4j使用的是log4j 1.2.x。
配置文件使用的是log4j.xml配置文件格式，没有使用log4j.properties文件形式，但是基本差不多。
2.需求
多线程，多节点，每天一个模块要产生2-3GB的日志，分散到8个节点，每个节点差不多400-500MB。打开和查询非常麻烦，而且不能够使用ctrl+f全文搜索，每次使用全文搜索，CPU占用率都会达到85+%。所以需要将日志文件按照小时切割。
3.遇到的坑
坑1
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
<appender name="ConsoleAppender" class="org.apache.log4j.ConsoleAppender">
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss.SSS} [%t] [%-5p] %c - %m%n" />
layout>
<filter class="org.apache.log4j.varia.LevelRangeFilter">
<param name="levelMin" value="INFO" />
<param name="levelMax" value="ERROR" />
<param name="AcceptOnMatch" value="true" />
filter>
appender>
<appender name="RollingFileAppender" class="org.apache.log4j.DailyRollingFileAppender">
<param name="DatePattern" value="'.'yyyy-MM-dd-HH'.log'" />
<param name="Encoding" value="UTF-8" />
<param name="File" value="${catalina.home}/logs/txbd.log" />
<param name="Append" value="true" />
<param name="Threshold" value="DEBUG" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss.SSS} [%t] [%-5p] %c - %m%n" />
layout>
appender>
<root>
<priority value ="DEBUG" />
<appender-ref ref="ConsoleAppender" />
<appender-ref ref="RollingFileAppender" />
root>
log4j:configuration>理论上产生的结果：当前的日志名为txbd.log，等到下一个小时后会产生一个备份的日志文件txbd.log2018-01-01.log文件。
出现了LOG4J:ERROR Failed to rename的错误。
查看源码后发现源码的内容：
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{
setFile(fileName, true, bufferedIO, bufferSize);
}catch(IOException e){
errorHandler.error("setFile(" + fileName + ", true) call failed.");
}这个原因在于日志文件被线程占用，rename操作服务进行，所以会提示这个错误
解决办法：看了网上的解决办法，清一色的是将rename改成copy方法。新创建一个文件，然后将上一小时的日志拷贝到这个文件中？试一下。
坑2
自定义DailyRollingFileAppender类，将rename方法改成copy方法
/**
* log4j日志拓展类
* 将新文件写入到txbd.log
* 旧文件写入到txbd.logyyyy-MM-dd-HH.log文件中
* 修复无法rename的bug，但是出现了写入后又被清理掉的问题（待解决）
* @author T
*/
public class DailyRollingFileAppenderX1 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;
private String datePattern = "'.'yyyy-MM-dd";
private String scheduledFilename;
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");
public DailyRollingFileAppenderX1() {
}
public DailyRollingFileAppenderX1 (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;
}
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+"].");
}
}
int computeCheckPeriod() {
RollingCalendar rollingCalendar = new RollingCalendar(gmtTimeZone, Locale.getDefault());
// 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...
}
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()) {
target.delete();
}
File file = new File(fileName);
boolean result = copy(file, target);
System.out.println("=====>进行日志文件拆分："+fileName);
if (result) {
//增加清空日志的方法，在复制成功后，清空原来的日志
FileWriter fw = new FileWriter(file);
fw.write("");
fw.flush();
fw.close();
LogLog.debug(fileName + " -> " + scheduledFilename);
} else {
System.out.println("=====>日志文件拆分失败");
LogLog.error("Failed to rename [" + fileName + "] to [" + scheduledFilename + "].");
}
try {
this.setFile(fileName, true, this.bufferedIO, this.bufferSize);
}
catch(IOException e) {
errorHandler.error("setFile("+fileName+", true) call failed.");
}
scheduledFilename = datedFilename;
}
/**
* 日志文件复制
* @param src 源文件名
* @param dst 新文件名
* @return
* @throws IOException
*/
private 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." );
return false;
} catch (IOException e) {
LogLog.error("文件读写错误.");
return false;
}
}
private boolean copy2(File file1, File file2) throws IOException{
// 3.将创建的节点流的对象作为形参传递给缓冲流的构造器中
BufferedInputStream bis = null;
BufferedOutputStream bos = null;
try{
// 2.创建相应的节点流
FileInputStream fis = new FileInputStream(file1);
FileOutputStream fos = new FileOutputStream(file2);
bis = new BufferedInputStream(fis);
bos = new BufferedOutputStream(fos);
// 4.实现文件的复制
byte[] b = new byte[4096];// 每次运20个，可按照实际文件大小调整
int len;
while ((len = bis.read(b)) != -1){
bos.write(b, 0, len);
}
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
} finally {
// 关闭相应的流
if (bos != null) {
try {
bos.close();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (bis != null){
try {
bis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
}
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);
}
}
class RollingCalendar1 extends GregorianCalendar {
private static final long serialVersionUID = -3560331770601814177L;
int type = DailyRollingFileAppenderX1.TOP_OF_TROUBLE;
RollingCalendar1() {
super();
}
RollingCalendar1(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 DailyRollingFileAppenderX1.TOP_OF_MINUTE:
this.set(Calendar.SECOND, 0);
this.set(Calendar.MILLISECOND, 0);
this.add(Calendar.MINUTE, 1);
break;
case DailyRollingFileAppenderX1.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 DailyRollingFileAppenderX1.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 DailyRollingFileAppenderX1.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 DailyRollingFileAppenderX1.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 DailyRollingFileAppenderX1.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();
}
}写了两个copy方法，效果是一样的。
感觉应该没问题哈！
结果一测试，发现文件都生成了，但是备份的日志文件不完整，确切说就是只备份了一点点的日志信息。
经过观察发现，日志确实是全部写入到了备份的日志文件中。但是，写完之后，备份文件立马就被清理掉了！
这个问题是很奇怪，怀疑是：
//增加清空日志的方法，在复制成功后，清空原来的日志
FileWriter fw = new FileWriter(file);
fw.write("");
fw.flush();
fw.close();这段程序有问题，导致日志被清理掉。
后来将这部分注释掉，确实日志都备份的比较完整。但是又引入了一个新的问题：日志重复。
所以这段肯定是不能注释的。
猜测应该是流没有刷新的问题，未进行下去
对于网上那些不经过实验，就乱转发文章的作者表示无奈
4.找到了自己想要的方案
前面遇到了问题，都行不通，那么可不可以换一个角度想想呢：
创建新文件，将日志写入到新文件中
/**
* 日志拓展类，按照小时为单位，每小时会生成一个新文件，并将接下来的一小时的日志写入到改文件中
* @author T
*/
public class DailyRollingFileAppenderX extends RollingFileAppender {
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;
private String datePattern = "'.'yyyy-MM-dd-HH";
private String scheduledFilename;
private long nextCheck = System.currentTimeMillis() - 1L;
private String val;
Date now = new Date();
SimpleDateFormat sdf;
RollingCalendar rc = new RollingCalendar();
int checkPeriod = -1;
static final TimeZone gmtTimeZone = TimeZone.getTimeZone("GMT");
public DailyRollingFileAppenderX() {
}
public DailyRollingFileAppenderX(Layout layout, String filename) throws IOException {
super(layout, filename);
//System.out.println("------------------");
}
public DailyRollingFileAppenderX(Layout layout, String filename, String datePattern) throws IOException {
super(layout, filename, true);
// System.out.println(new SimpleDateFormat("'"+filename+"'yyyy-MM-dd'.log'").format(new Date()));
this.datePattern = datePattern;
activateOptions();
}
public void setDatePattern(String pattern) {
this.datePattern = pattern;
}
public String getDatePattern() {
return this.datePattern;
}
public void setFile(String file) {
// Trim spaces from both ends. The users probably does not want
// trailing spaces in file names.
this.val = file.trim();
SimpleDateFormat formats = new SimpleDateFormat("'" + val + "'yyyy-MM-dd-HH'.log'");
String fileNameNew = formats.format(new Date());
fileName = fileNameNew;
}
public void activateOptions() {
super.activateOptions();
if ((this.datePattern != null) && (this.fileName != null)) {
this.now.setTime(System.currentTimeMillis());
this.sdf = new SimpleDateFormat(this.datePattern);
int type = computeCheckPeriod();
printPeriodicity(type);
this.rc.setType(type);
File file = new File(fileName);
this.scheduledFilename = (this.fileName + this.sdf.format(new Date(file.lastModified())));
} else {
LogLog.error("Either File or DatePattern options are not set for appender [" + this.name + "].");
}
}
void printPeriodicity(int type) {
switch (type) {
case 0:
LogLog.debug("Appender [" + this.name + "] to be rolled every minute.");
break;
case 1:
LogLog.debug("Appender [" + this.name + "] to be rolled on top of every hour.");
break;
case 2:
LogLog.debug("Appender [" + this.name + "] to be rolled at midday and midnight.");
break;
case 3:
LogLog.debug("Appender [" + this.name + "] to be rolled at midnight.");
break;
case 4:
LogLog.debug("Appender [" + this.name + "] to be rolled at start of week.");
break;
case 5:
LogLog.debug("Appender [" + this.name + "] to be rolled at start of every month.");
break;
default:
LogLog.warn("Unknown periodicity for appender [" + this.name + "].");
}
}
int computeCheckPeriod() {
RollingCalendar rollingCalendar = new RollingCalendar(gmtTimeZone,Locale.getDefault());
Date epoch = new Date(0L);
if (this.datePattern != null) {
for (int i = 0; i <= 5; i++) {
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(this.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 != null) && (r1 != null) && (!r0.equals(r1))) {
return i;
}
}
}
return -1;
}
public void rollOver() {
if (this.datePattern == null) {
this.errorHandler.error("Missing DatePattern option in rollOver().");
return;
}
// System.out.println("rollOver() 1111");
String datedFilename = this.fileName + this.sdf.format(this.now);
if (this.scheduledFilename.equals(datedFilename)) {
return;
}
closeFile();
File target = new File(this.scheduledFilename);
if (target.exists()) {
target.delete();
}
File file = new File(this.fileName);
// 重命名文件。
/*
* boolean result = file.renameTo(target); if (result)
* LogLog.debug(this.fileName + " -> " + this.scheduledFilename); else {
* LogLog.error("Failed to rename [" + this.fileName + "] to [" +
* this.scheduledFilename + "]."); }
*/
// 新建文件
try {
SimpleDateFormat formats = new SimpleDateFormat("'" + this.val + "'yyyy-MM-dd-HH'.log'");
this.fileName = formats.format(new Date());
setFile(this.fileName, true, this.bufferedIO, this.bufferSize);
} catch (IOException e) {
this.errorHandler.error("setFile(" + this.fileName + ", true) call failed.");
}
this.scheduledFilename = datedFilename;
}
protected void subAppend(LoggingEvent event) {
long n = System.currentTimeMillis();
if (n >= this.nextCheck) {
this.now.setTime(n);
this.nextCheck = this.rc.getNextCheckMillis(this.now);
rollOver();
}
super.subAppend(event);
}
}
class RollingCalendar extends GregorianCalendar {
private static final long serialVersionUID = -3560331770601814177L;
int type = -1;
RollingCalendar() {
}
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) {
setTime(now);
switch (this.type) {
case 0:
set(13, 0);
set(14, 0);
add(12, 1);
break;
case 1:
set(12, 0);
set(13, 0);
set(14, 0);
add(11, 1);
break;
case 2:
set(12, 0);
set(13, 0);
set(14, 0);
int hour = get(11);
if (hour < 12) {
set(11, 12);
} else {
set(11, 0);
add(5, 1);
}
break;
case 3:
set(11, 0);
set(12, 0);
set(13, 0);
set(14, 0);
add(5, 1);
break;
case 4:
set(7, getFirstDayOfWeek());
set(11, 0);
set(12, 0);
set(13, 0);
set(14, 0);
add(3, 1);
break;
case 5:
set(5, 1);
set(11, 0);
set(12, 0);
set(13, 0);
set(14, 0);
add(2, 1);
break;
default:
throw new IllegalStateException("Unknown periodicity type.");
}
return getTime();
}
}将原来的rename和copy都舍弃掉，然后将文件改成yyyy-MM-dd-HH。
配置文件引入自定义的日志类：
<appender name="RollingFileAppender" class="com.uitis.util.DailyRollingFileAppenderX">结果：好了
这里的日志文件格式尽量与配置文件保持一致。不然可能生成的文件名会有问题。但是即使文件名有问题，也不会丢失日志。