Package org.codehaus.plexus.util

Class DirectoryScanner

java.lang.Object
org.codehaus.plexus.util.AbstractScanner
org.codehaus.plexus.util.DirectoryScanner
All Implemented Interfaces:
Scanner
public class DirectoryScanner extends AbstractScanner

Class for scanning a directory for files/directories which match certain criteria.

These criteria consist of selectors and patterns which have been specified. With the selectors you can select which files you want to have included. Files which are not selected are excluded. With patterns you can include or exclude files based on their filename.

The idea is simple. A given directory is recursively scanned for all files and directories. Each file/directory is matched against a set of selectors, including special support for matching against filenames with include and and exclude patterns. Only files/directories which match at least one pattern of the include pattern list or other file selector, and don't match any pattern of the exclude pattern list or fail to match against a required selector will be placed in the list of files/directories found.

When no list of include patterns is supplied, "**" will be used, which means that everything will be matched. When no list of exclude patterns is supplied, an empty list is used, such that nothing will be excluded. When no selectors are supplied, none are applied.

The filename pattern matching is done as follows: The name to be matched is split up in path segments. A path segment is the name of a directory or file, which is bounded by File.separator ('/' under UNIX, '\' under Windows). For example, "abc/def/ghi/xyz.java" is split up in the segments "abc", "def","ghi" and "xyz.java". The same is done for the pattern against which should be matched.

The segments of the name and the pattern are then matched against each other. When '**' is used for a path segment in the pattern, it matches zero or more path segments of the name.

There is a special case regarding the use of File.separators at the beginning of the pattern and the string to match:
When a pattern starts with a File.separator, the string to match must also start with a File.separator. When a pattern does not start with a File.separator, the string to match may not start with a File.separator. When one of these rules is not obeyed, the string will not match.

When a name path segment is matched against a pattern path segment, the following special characters can be used:
'*' matches zero or more characters
'?' matches one character.

Examples:
  • "**\*.class" matches all .class files/dirs in a directory tree.
  • "test\a??.java" matches all files/dirs which start with an 'a', then two more characters and then ".java", in a directory called test.
  • "**" matches everything in a directory tree.
  • "**\test\**\XYZ*" matches all files/dirs which start with "XYZ" and where there is a parent directory called test (e.g. "abc\test\def\ghi\XYZ123").

Case sensitivity may be turned off if necessary. By default, it is turned on.

Example of usage: 
 String[] includes = { "**\\*.class" };
 String[] excludes = { "modules\\*\\**" };
 ds.setIncludes( includes );
 ds.setExcludes( excludes );
 ds.setBasedir( new File( "test" ) );
 ds.setCaseSensitive( true );
 ds.scan();

 System.out.println( "FILES:" );
 String[] files = ds.getIncludedFiles();
 for ( int i = 0; i < files.length; i++ )
 {
     System.out.println( files[i] );
 }

This will scan a directory called test for .class files, but excludes all files in all proper subdirectories of a directory called "modules"

Author:
Arnout J. Kuiper ajkuiper@wxs.nl, Magesh Umasankar, Bruce Atherton, Antoine Levy-Lambert