Log4j created file not able to delete while testing my application??

[j.gohel]

Hi,

1)
In my web-based application i am using log4j for debugging my application.But the problem i m facing is that whenever i have to delete the logs generated while the Tomcat Server is on that is i am testing my application, i am able to delete the logs but not able to save the file so all the logs i deleted diplays again plus the new one generated.The system
says the file is in use?? So i have to shutdown my tomcat & then the file gets saved .So how to get rid of this problem .

Also how can i generate different files whenever i start my application so that i dont have to refer my old file for the logs.Does it need any extra configuration in my properties file i m using for log4j??

My properties file is like this.....

#
# Log for Java configuration don't change unless you know what you doing
# The possible values here are debug, info, warn, error, fatal
#
#log4j.rootCategory=info, R

log4j.rootCategory=debug, R


#
# Dont change this
#
log4j.appender.R=org.apache.log4j.RollingFileAppender

#
# This is the file that becomes the log file. Older log files are renamed as fileName1 fileName2 etc.
#
#log4j.appender.R.File=C:\\jakarta-tomcat-4.0.1\\webapps\\FileXDMS\\WEB-INF\\fileXDMS.log
log4j.appender.R.File=C:/JIGNESH/gmg.log


#
# The maximum size of the log file, good idea to keep the size small.
#
log4j.appender.R.MaxFileSize=100KB


#
# This defines the no of log files to keep. Since this is a rolling file system, after the number of
# files reaches this number, the oldest file is rewritten
# 
log4j.appender.R.MaxBackupIndex=10

#
# Dont change this
#
log4j.appender.R.layout=org.apache.log4j.PatternLayout

#
# This defines the way comments are written to the log file, for e.g. %d tells the logger to write the date
# for a full list see the log4j manual. %p is the priority (debug, info etc as defined above)
#
log4j.appender.R.layout.ConversionPattern=%d{dd MMM yyyy HH:mm:ss} -- %p -- %m%n

2)
One more thing i am generating some csv files from my application but they doesn't get deleted while my server remains ON. This should not happen as my application will be used by many users through web..

What i want to do is create the csv files actually they are a form of reports so each individual user should be able to generate report in the file system of their own PC.Currently my files are getting generated on the fileSystem where i m developing my application, ie on server's file system...

So help me sort out these two queries...

Thanks,
Jignesh

[Belisarius]

This is taking place on a Windows machine?

[j.gohel]

yes it on the Windows machine....

[Belisarius]

If you have a file open for writing in Windows, Windows will put a lock on it. This is different from Unix, where you can delete just about anything. You'll have trouble deleteing files until whatever program is accessing them gives up the lock.

[j.gohel]

And what about creating different log4j file whenever my application starts newly everytime???

Also i am generating some report files through my application & this application would be used by many users across web..

So each individual user who would be using the application should be able to get that generated reports or rather generate in the file system of their own PC.Currently my files are getting generated on the fileSystem where i m developing & testing my application, ie on server's file system...So how can i make it possible to generate the files on user's local PC & not on server??

If its very difficult then suggest some alternatives regarding the same....

Thanks,
Jignesh

[Belisarius]

I'm honestly not familiar enough with log4j to know how to customize logfile creation, sorry.

As for sending the user a file, the best way to do it is using ServletResponse (it's an implicit variable available to JSPs, the "response" variable).

What you do is you send the client a MIME type, letting them know what kind of file it is, and then stream the data to them. This is secure because you're controlling access to the stream (based on a users session, I assume). You also don't need to take up diskspace, as you can generate the reports on the fly. However, the tradeoff is in CPU and memory utilization, so you might want to store them locally and then stream the files (as opposed to offer them up for download).

Originally Posted by j.gohel

And what about creating different log4j file whenever my application starts newly everytime???

Also i am generating some report files through my application & this application would be used by many users across web..

So each individual user who would be using the application should be able to get that generated reports or rather generate in the file system of their own PC.Currently my files are getting generated on the fileSystem where i m developing & testing my application, ie on server's file system...So how can i make it possible to generate the files on user's local PC & not on server??

If its very difficult then suggest some alternatives regarding the same....

Thanks,
Jignesh

[j.gohel]

Thanks Belisarius for all your support.

If u dont mind can you please tell me the general steps like a sort of algorithm or some pseudocode to achieve this thing : generating the reports on the fly & sending it in response.My report type is .xls.& the design pattern i am using is MVC so all my work goes through a single controller.

Regards,
Jignesh

[Belisarius]

I've never done this, so I can't vouch for the efficiency or correctness of this. Also, I'm not really used to working with Streams, so that's another thing you'll have to test and work out.

FileInputStream fis = new FileInputStream(<file location>);
int fileLength = fis.available();
byte[] bytes = new byte[fileLength];
fis.read(bytes);

response.setContentType(<XLS content flag>);
response.getOutputStream().write(bytes);
response.getOutputStream().flush();
response.getOutputStream().close();
fis.close();

Alternately, you could do it this way:

FileInputStream fis = new FileInputStream(<file location>);
int fileLength = fis.available();
response.setContentType(<XLS content flag>);
for(int i =0; i < fileLength; i++){
  byte current = fis.read();
  response.getOutputStream().write(current);
}

response.getOutputStream().flush();
response.getOutputStream().close();
fis.close();

That may or may not be more efficient/use a smaller footprint. You'll have to experiment to find out.

[j.gohel]

Thank u very much Belisarius for all ur cooperation.
Thanks once again.

Regards,
jignesh

[j.gohel]

Hi Belisarius,

response.getOutputStream().write(current);

Like this i will write the raw bytes to the response.
But on the user's file system i want to save this written bytes to a particular location so for that i will ahve to create some files in the user file system dynamically .So how to do that???

Thanks,
Jignesh

[Belisarius]

I'm not sure I follow what you want to do, but the end user should simply see this as an incoming file and save it as they would any other file.

[j.gohel]

Hi,

Now, I am able to download & save the files as excel files.
But one problem:
When i have a single file i am able to download & save it easily.

But in some cases i have mutiple files to be downloaded & saved so how can i do this thing of downloading & saving multiple files coming in the response.

Also i am not able to delete my file on the server after downloading it

Here is my code for downloading my reports:

 public boolean downloadReport(String dirPath,HttpServletResponse response)
  {
	    FileInputStream fis = null;

		boolean flag = false;
		File f = new File(dirPath);
		ArrayList tempFileArrList = new ArrayList();
					
		if(f.isDirectory())
		{
			File[] fArray = f.listFiles();

			for(int i = 0; i < fArray.length; i++)
			{							
				log.debug("File Names Array Content : fArray [" + i + "]" + fArray[i]);
				
				if(fArray[i].exists())
				{
					try
					{
						fis = new FileInputStream(fArray[i]);
						int fileLength = fis.available();
						byte[] bytes = new byte[fileLength];
						fis.read(bytes);
						response.setContentType("application/vnd.ms-excel");
						response.setHeader("Content-Disposition","attachment; filename = \"myxlfile.xls\" ");
						response.getOutputStream().write(bytes);
						response.getOutputStream().flush();
						//response.getOutputStream().close();
						//fis.close();
						tempFileArrList.add(fArray[i]);
						//fArray[i].delete();
						log.debug("DEBUG 10");
						flag = true;
					}
					catch(IOException ioe)
					{
						log.debug("IOException in GMGController while download "+ioe);
						flag = false;
					}
					catch(Exception e)
					{
						log.debug("Exception in GMGController while download "+e);
						flag = false;
					}	

				}
				else
				{
					continue;
				}
											
			}

			try
			{
				response.getOutputStream().close();
				fis.close();
				flag = true;
			}
			catch(IOException ioe)
			{
				log.debug("IOException in GMGController while closing "+ioe);
				flag = false;
			}
			catch(Exception e)
			{
				log.debug("Exception in GMGController while closing "+e);
				flag = false;
			}	

		}

	  for(int i = 0; i < tempFileArrList.size(); i++ )
	  {
			File file = (File)tempFileArrList.get(i);

			if(file.exists())
			{
				log.info("Deleting file "+ (i+1) + "  "+ file.getName());
				file.delete();
			}
	  }

	  return flag;
  }

Help me sorting out this...
Jignesh

[Belisarius]

You can't send multiple files for download - it's just not possible over existing protocols. You'll need to initiate several transfers. You could simply zip up the multiple files and send them through.

As for deleting, does the user running Tomcat have write permissions to those files?