org.apache.felix.fileinstall.internal

Class Scanner

java.lang.Object

org.apache.felix.fileinstall.internal.Scanner

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

WatcherScanner

public class Scanner
extends Object
implements Closeable

A Scanner object is able to detect and report new, modified and deleted files. The scanner use an internal checksum to identify the signature of a file or directory. The checksum will change if the file or any of the directory's child is modified. In addition, if the scanner detects a change on a given file, it will wait until the checksum does not change anymore before reporting the change on this file. This allows to not report the change until a big copy if complete for example.

Constructor Summary

Constructors

Constructor and Description
Scanner(File directory) Create a scanner for the specified directory
Scanner(File directory, String filterString) Create a scanner for the specified directory and file filter

Method Summary

Modifier and Type	Method and Description
void	close()
long	getChecksum(File file) Retrieve the previously computed checksum for a give file.
void	initialize(Map<File,Long> checksums) Initialize the list of known files.
Set<File>	scan(boolean reportImmediately) Report a set of new, modified or deleted files.
void	updateChecksum(File file) Update the checksum of a file if that file is already known locally.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Scanner

public Scanner(File directory)

Create a scanner for the specified directory

Parameters:

directory - the directory to scan

Scanner

public Scanner(File directory,
               String filterString)

Create a scanner for the specified directory and file filter

Parameters:

directory - the directory to scan

filterString - a filter for file names

Method Detail

initialize

public void initialize(Map<File,Long> checksums)

Initialize the list of known files. This should be called before the first scan to initialize the list of known files. The purpose is to be able to detect files that have been deleted while the scanner was inactive.

Parameters:

checksums - a map of checksums

scan

public Set<File> scan(boolean reportImmediately)

Report a set of new, modified or deleted files. Modifications are checked against a computed checksum on some file attributes to detect any modification. Upon restart, such checksums are not known so that all files will be reported as modified.

Parameters:

reportImmediately - report all files immediately without waiting for the checksum to be stable

Returns:

a list of changes on the files included in the directory

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

getChecksum

public long getChecksum(File file)

Retrieve the previously computed checksum for a give file.

Parameters:

file - the file to retrieve the checksum

Returns:

the checksum

updateChecksum

public void updateChecksum(File file)

Update the checksum of a file if that file is already known locally.