Class DirectoryScanner

  • Direct Known Subclasses:
    SftpPathDirectoryScanner

    public class DirectoryScanner
    extends PathScanningMatcher

    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".

    • Field Detail

      • basedir

        protected java.nio.file.Path basedir
        The base directory to be scanned.
    • Constructor Detail

      • DirectoryScanner

        public DirectoryScanner()
      • DirectoryScanner

        public DirectoryScanner​(java.nio.file.Path dir)
      • DirectoryScanner

        public DirectoryScanner​(java.nio.file.Path dir,
                                java.lang.String... includes)
      • DirectoryScanner

        public DirectoryScanner​(java.nio.file.Path dir,
                                java.util.Collection<java.lang.String> includes)
    • Method Detail

      • setBasedir

        public void setBasedir​(java.nio.file.Path basedir)
        Sets the base directory to be scanned. This is the directory which is scanned recursively.
        Parameters:
        basedir - The base directory for scanning. Should not be null.
      • getBasedir

        public java.nio.file.Path getBasedir()
        Returns the base directory to be scanned. This is the directory which is scanned recursively.
        Returns:
        the base directory to be scanned
      • scan

        public java.util.Collection<java.nio.file.Path> scan()
                                                      throws java.io.IOException,
                                                             java.lang.IllegalStateException
        Scans the base directory for files which match at least one include pattern and don't match any exclude patterns. If there are selectors then the files must pass muster there, as well.
        Returns:
        the matching files
        Throws:
        java.lang.IllegalStateException - if the base directory was set incorrectly (i.e. if it is null, doesn't exist, or isn't a directory).
        java.io.IOException - if failed to scan the directory (e.g., access denied)
      • scan

        public <C extends java.util.Collection<java.nio.file.Path>> C scan​(java.util.function.Supplier<? extends C> factory)
                                                                    throws java.io.IOException,
                                                                           java.lang.IllegalStateException
        Throws:
        java.io.IOException
        java.lang.IllegalStateException
      • scandir

        protected <C extends java.util.Collection<java.nio.file.Path>> C scandir​(java.nio.file.Path rootDir,
                                                                                 java.nio.file.Path dir,
                                                                                 C filesList)
                                                                          throws java.io.IOException
        Scans the given directory for files and directories. Found files and directories are placed in their respective collections, based on the matching of includes, excludes, and the selectors. When a directory is found, it is scanned recursively.
        Type Parameters:
        C - Target matches collection type
        Parameters:
        rootDir - The directory to scan. Must not be null.
        dir - The path relative to the root directory (needed to prevent problems with an absolute path when using dir). Must not be null.
        filesList - Target Collection to accumulate the relative path matches
        Returns:
        Updated files list
        Throws:
        java.io.IOException - if failed to scan the directory