Re: Deleting files modified before a specified number of days using Java.
- From: Lew <lew@xxxxxxxxxxxxx>
- Date: Thu, 27 Dec 2007 05:27:33 -0500
Sameer wrote:
We have one server (FTP). One drive of which stores scanned documents.
Users usually upload documents (.JPG files). Currently that drive is
of about 27 GB containing more that 1,50,000 files.
We have to keep data of 45 days only and have to remove other files
regularly. Currently we use the AWK like utility for the same. It has
some limitations and it do not accept command line parameters and
therefore can not be scheduled as a program.
Now i have written one Java program for the same.
The java file as a Google document:
http://docs.google.com/View?docid=dfvj6k7q_3x4pr28gf
This program wont help. I am running the program from the server.
But it just got hanged after
ile = new File(dirPath);
fileArray = file.listFiles(this);
Not even able to create the fileArray object....
Do increasing memory of server will help or how to change the program?
It's not a memory problem, it's a bug in the way you wrote the program.
I don't think multi-threading like concepts will help as the file
number is big.
Plus, multi-threaded programs are harder to get correct. Get the single-threaded one right first.
What should i do to make it work or any other suggstions to carry out
the server files deletion task.
Start with the little things - class names really should start with an upper-case letter, by widespread convention. You really should indent your code appropriately. Violation of those two conventions made it very difficult to read the listing.
A good way to name a class is in two parts representing a noun phrase, e.g., FileDeleter.
Now the reason for your bug. The class is doing too much work in the constructor - the constructor should only construct, nothing more. You have it placing an incomplete object as the FileFilter for the listFiles() call. No wonder you have trouble.
Build the FileFilter in the constructor, but use it from another method; I suggest deleteFiles() (which you could rename to, say, run()). That would let you take the variable 'fileArray' and 'dirPath' out of the member attributes and make them local variables only. ('dirPath' would be local to the constructor, and 'fileArray' to the method.)
Speaking of deleteFiles(), variables should not have underscores in their names, "no_of_files". Use camelCase, where each word part except the first is capitalized, "noOfFiles".
public class FileDeleter implements Runnable
{
// members should be private!
private final File file;
private final int daysKeep;
// notice the 'public' visibility of the constructor
public FileDeleter( String path, int days )
{
file = new File( path );
if ( file == null || ! file.isDirectory() )
{
String err = dirPath +" not a directory.";
System.err.println( err );
throw new IllegalArgumentException( err );
}
daysKeep = days;
}
@Override public void run()
{
File [] files = file.listFiles( new FileFilter()
{
@Override public boolean accept( File p )
{
return ( ! f.isDirectory() && daysSince( f ) > daysKeep );
}
} );
if ( files != null && files.length > 0 )
{
delete( files );
}
}
private void delete( File [] files )
{
for ( File f : files )
{
f.delete();
}
}
private static final int PERDIEM = 86400000;
private int daysSince( File f )
{
return (int) ( (new Date().getTime() - f.lastModified()) / PERDIEM);
}
}
Throw in some imports and a test client and Bob's your uncle.
--
Lew
.
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