Changing Timestamp of HtmlLayout of log4j

Hi All,

I am using HTMLLayout for logging using log4j.

I want to change the default timestamp that comes with HTMLLayout.
something like this 2008-01-28 17:13:02,057 .

Please let me know how can we do that.

Thanks in advance

Yes this can be done in the log4j.properties (or lg4j.xml) file, it's called a conversion pattern. See here for details.

Hint: It takes Java SimpleDateFormat compatible formats

Hope that helps!

Trying conversion pattern like below is not working, as HTML layout donot extend pattern layout.

log4j.appender.MY_FILE=org.apache.log4j.RollingFileAppender
log4j.appender.MY_FILE_FILE.File=logs/myfile/MyLog.html
log4j.appender.MY_FILE_FILE.MaxFileSize=2500KB
log4j.appender.MY_FILE_FILE.MaxBackupIndex=5
log4j.appender.MY_FILE_FILE.Append=true
log4j.appender.MY_FILE_FILE.layout=org.apache.log4j.HTMLLayout
#log4j.appender.MY_FILE_FILE.layout.ConversionPattern=[%d{MMM dd HH:mm:ss}] %-5p (%F:%L) - %m%n

Hi Esha,

Hmm, you seem to be quite right. In that case I'm not sure of any option but to write a custom class that extends HTMLLayout, see here for a guide.

I had this same desire: to alter the format of the timestamp in log records produced by Log4J's HTMLLayout. After some extensive Googling, it appeared that there were only 3 options:

Re-invent the wheel and write a custom HTMLLayout class

Extend the Log4J HTMLLayout class and replace the format() method

Modify the source code for the Log4J HTMLLayout class

Unfortunately, none of these were very appealing options; all I needed was to change the format of the timestamp!

Then it hit me: there's another option that involves overriding the format() method, but not rewriting it in its entirety. What I decided to do was write a custom HTML layout class and intercept the log record (by overriding the format() method) and use RegEx to locate and replace the timestamp with one having the desired format. And the beauty of it is that the format can be specified externally as a property in the log4j configuration file!

Sample code for my layout class is shown below.

package com.mypackage;
 
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
import org.apache.log4j.spi.LoggingEvent;
 
/**
 * This HTML Log Formatter is a simple replacement for the standard Log4J HTMLLayout formatter and
 * replaces the default timestamp (milliseconds, relative to the start of the log) with a more readable
 * timestamp (an example of the default format is 2008-11-21-18:35:21.472-0800).
 * */
 
public class   MyLayout
       extends org.apache.log4j.HTMLLayout
 
{
// RegEx pattern looks for <tr> <td> nnn...nnn </td> (all whitespace ignored)

private static final String rxTimestamp = "\\s*<\\s*tr\\s*>\\s*<\\s*td\\s*>\\s*(\\d*)\\s*<\\s*/td\\s*>";

//* The timestamp format. The format can be overriden by including the following 
  * property in the Log4J configuration file:
  *
  * log4j.appender.<category>.layout.TimestampFormat
  *
  * using the same format string as would be specified with SimpleDateFormat.
  *
  */

private String timestampFormat = "yyyy-MM-dd-HH:mm:ss.SZ"; // Default format. Example: 2008-11-21-18:35:21.472-0800

private SimpleDateFormat sdf = new SimpleDateFormat(timestampFormat);

public MyLayout()
{
super();
}

/** Override HTMLLayout's format() method */

public String format(LoggingEvent event)
{
String record = super.format(event); // Get the log record in the default HTMLLayout format.

Pattern pattern = Pattern.compile(rxTimestamp);  // RegEx to find the default timestamp
Matcher matcher = pattern.matcher(record);

if (!matcher.find()) // If default timestamp cannot be found,
{
return record; // Just return the unmodified log record.
}

StringBuffer buffer = new StringBuffer(record);

buffer.replace(matcher.start(1), // Replace the default timestamp with one formatted as desired.
       matcher.end(1),
       sdf.format(new Date(event.timeStamp)));

return buffer.toString(); // Return the log record with the desired timestamp format.
}

/** Setter for timestamp format. Called if log4j.appender.<category>.layout.TimestampFormat property is specfied */

public void setTimestampFormat(String format) 
{
    this.timestampFormat = format;
this.sdf = new SimpleDateFormat(format); // Use the format specified by the TimestampFormat property
}

/** Getter for timestamp format being used. */

public String getTimestampFormat()
{
return this.timestampFormat;
}
 
}

Hey John,

Nice solution, I like the creativity there! I'm blatantly ripping off your code for future personal use

No problem, Martijn. Glad I could help. I just hate it when I can't do something that should be simple. Fortunately, this one yielded without too much trouble -- once I finally hit on the solution!

hi.. i too faced same html layout date/time problem.. i created custom layout but how can i import this custom class into log4j API?? or how will Jboss take this class?? please help??

thanks in advance...

Hi Veera and welcome to Javaranch!

Note the

So you can simply add this class to the log4j package or (probably better), just make sure it's in the CLASSPATH that your log4j.jar is in.

Sweet...brute force.

Hi Brent and welcome to Javaranch! I'm not sure what your Brute force comment alludes to?

Hi John,

I tried to run the solution that you had provided above i.e. overriding of format method. But i failed to run that. Please can you provide me solution how to run that? I mean to run that class i must have main method inside that class. So, in that main method how to call format()?
If we write main method in that class and call format method then What would be the parameter for format method?
Or is there any method to call that class from log4j.properties?

Please reply me with solution as soon as possible.

Thanks & Regard,
Iti Garg