Package jodd.io

Class FileNameUtil

java.lang.Object
jodd.io.FileNameUtil
public class FileNameUtil extends Object
General filename and filepath manipulation utilities.

When dealing with filenames you can hit problems when moving from a Windows based development machine to a Unix based production machine. This class aims to help avoid those problems.

NOTE: You may be able to avoid using this class entirely simply by using JDK File objects and the two argument constructor File(File,String).

Most methods on this class are designed to work the same on both Unix and Windows. Those that don't include 'System', 'Unix' or 'Windows' in their name.

Most methods recognise both separators (forward and back), and both sets of prefixes. See the javadoc of each method for details.

This class defines six components within a filename (example C:\dev\project\file.txt):

  • the prefix - C:\
  • the path - dev\project\
  • the full path - C:\dev\project\
  • the name - file.txt
  • the base name - file
  • the extension - txt
Note that this class works best if directory filenames end with a separator. If you omit the last separator, it is impossible to determine if the filename corresponds to a file or a directory. As a result, we have chosen to say it corresponds to a file.

This class only supports Unix and Windows style names. Prefixes are matched as follows: 


 Windows:
 a\b\c.txt           --> ""          --> relative
 \a\b\c.txt          --> "\"         --> current drive absolute
 C:a\b\c.txt         --> "C:"        --> drive relative
 C:\a\b\c.txt        --> "C:\"       --> absolute
 \\server\a\b\c.txt  --> "\\server\" --> UNC

 Unix:
 a/b/c.txt           --> ""          --> relative
 /a/b/c.txt          --> "/"         --> absolute
 ~/a/b/c.txt         --> "~/"        --> current user
 ~                   --> "~/"        --> current user (slash added)
 ~user/a/b/c.txt     --> "~user/"    --> named user
 ~user               --> "~user/"    --> named user (slash added)
Both prefix styles are matched always, irrespective of the machine that you are currently running on.

  • Field Details

    • EXTENSION_SEPARATOR

      private static final char EXTENSION_SEPARATOR
      The extension separator character.
      See Also:

    • UNIX_SEPARATOR

      private static final char UNIX_SEPARATOR
      The Unix separator character.
      See Also:

    • WINDOWS_SEPARATOR

      private static final char WINDOWS_SEPARATOR
      The Windows separator character.
      See Also:

    • SYSTEM_SEPARATOR

      private static final char SYSTEM_SEPARATOR
      The system separator character.

    • OTHER_SEPARATOR

      private static final char OTHER_SEPARATOR
      The separator character that is the opposite of the system separator.

  • Constructor Details

    • FileNameUtil

      public FileNameUtil()

  • Method Details

    • isSeparator

      private static boolean isSeparator(char ch)
      Checks if the character is a separator.

    • normalize

      public static String normalize(String filename)

    • normalize

      public static String normalize(String filename, boolean unixSeparator)
      Normalizes a path, removing double and single dot path steps.

      This method normalizes a path to a standard format. The input may contain separators in either Unix or Windows format. The output will contain separators in the format of the system.

      A trailing slash will be retained. A double slash will be merged to a single slash (but UNC names are handled). A single dot path segment will be removed. A double dot will cause that path segment and the one before to be removed. If the double dot has no parent path segment to work with, null is returned.

      The output will be the same on both Unix and Windows except for the separator character. 

      
 /foo//               -->   /foo/
 /foo/./              -->   /foo/
 /foo/../bar          -->   /bar
 /foo/../bar/         -->   /bar/
 /foo/../bar/../baz   -->   /baz
 //foo//./bar         -->   /foo/bar
 /../                 -->   null
 ../foo               -->   null
 foo/bar/..           -->   foo/
 foo/../../bar        -->   null
 foo/../bar           -->   bar
 //server/foo/../bar  -->   //server/bar
 //server/../bar      -->   null
 C:\foo\..\bar        -->   C:\bar
 C:\..\bar            -->   null
 ~/foo/../bar/        -->   ~/bar/
 ~/../bar             -->   null
      (Note the file separator returned will be correct for Windows/Unix)
      Parameters:
      filename - the filename to normalize, null returns null
      Returns:
      the normalized filename, or null if invalid

    • normalizeNoEndSeparator

      public static String normalizeNoEndSeparator(String filename)

    • normalizeNoEndSeparator

      public static String normalizeNoEndSeparator(String filename, boolean unixSeparator)
      Normalizes a path, removing double and single dot path steps, and removing any final directory separator.

      This method normalizes a path to a standard format. The input may contain separators in either Unix or Windows format. The output will contain separators in the format of the system.

      A trailing slash will be removed. A double slash will be merged to a single slash (but UNC names are handled). A single dot path segment will be removed. A double dot will cause that path segment and the one before to be removed. If the double dot has no parent path segment to work with, null is returned.

      The output will be the same on both Unix and Windows except for the separator character. 

      
 /foo//               -->   /foo
 /foo/./              -->   /foo
 /foo/../bar          -->   /bar
 /foo/../bar/         -->   /bar
 /foo/../bar/../baz   -->   /baz
 /foo//./bar          -->   /foo/bar
 /../                 -->   null
 ../foo               -->   null
 foo/bar/..           -->   foo
 foo/../../bar        -->   null
 foo/../bar           -->   bar
 //server/foo/../bar  -->   //server/bar
 //server/../bar      -->   null
 C:\foo\..\bar        -->   C:\bar
 C:\..\bar            -->   null
 ~/foo/../bar/        -->   ~/bar
 ~/../bar             -->   null
      (Note the file separator returned will be correct for Windows/Unix)
      Parameters:
      filename - the filename to normalize, null returns null
      Returns:
      the normalized filename, or null if invalid

    • doNormalize

      private static String doNormalize(String filename, char separator, boolean keepSeparator)
      Internal method to perform the normalization.
      Parameters:
      filename - file name
      separator - separator character to use
      keepSeparator - true to keep the final separator
      Returns:
      normalized filename

    • concat

      public static String concat(String basePath, String fullFilenameToAdd)
      Concatenates a filename to a base path using normal command line style rules.

      The effect is equivalent to resultant directory after changing directory to the first argument, followed by changing directory to the second argument.

      The first argument is the base path, the second is the path to concatenate. The returned path is always normalized via normalize(String), thus .. is handled.

      If pathToAdd is absolute (has an absolute prefix), then it will be normalized and returned. Otherwise, the paths will be joined, normalized and returned.

      The output will be the same on both Unix and Windows except for the separator character. 

      
 /foo/ + bar          -->   /foo/bar
 /foo + bar           -->   /foo/bar
 /foo + /bar          -->   /bar
 /foo + C:/bar        -->   C:/bar
 /foo + C:bar         -->   C:bar (*)
 /foo/a/ + ../bar     -->   foo/bar
 /foo/ + ../../bar    -->   null
 /foo/ + /bar         -->   /bar
 /foo/.. + /bar       -->   /bar
 /foo + bar/c.txt     -->   /foo/bar/c.txt
 /foo/c.txt + bar     -->   /foo/c.txt/bar (!)
      (*) Note that the Windows relative drive prefix is unreliable when used with this method. (!) Note that the first parameter must be a path. If it ends with a name, then the name will be built into the concatenated path. If this might be a problem, use getFullPath(String) on the base path argument.
      Parameters:
      basePath - the base path to attach to, always treated as a path
      fullFilenameToAdd - the filename (or path) to attach to the base
      Returns:
      the concatenated path, or null if invalid

    • concat

      public static String concat(String basePath, String fullFilenameToAdd, boolean unixSeparator)

    • doConcat

      public static String doConcat(String basePath, String fullFilenameToAdd, char separator)

    • separatorsToUnix

      public static String separatorsToUnix(String path)
      Converts all separators to the Unix separator of forward slash.
      Parameters:
      path - the path to be changed, null ignored
      Returns:
      the updated path

    • separatorsToWindows

      public static String separatorsToWindows(String path)
      Converts all separators to the Windows separator of backslash.
      Parameters:
      path - the path to be changed, null ignored
      Returns:
      the updated path

    • separatorsToSystem

      public static String separatorsToSystem(String path)
      Converts all separators to the system separator.
      Parameters:
      path - the path to be changed, null ignored
      Returns:
      the updated path

    • getPrefixLength

      public static int getPrefixLength(String filename)
      Returns the length of the filename prefix, such as C:/ or ~/.

      This method will handle a file in either Unix or Windows format.

      The prefix length includes the first slash in the full filename if applicable. Thus, it is possible that the length returned is greater than the length of the input string. 

      
 Windows:
 a\b\c.txt           --> ""          --> relative
 \a\b\c.txt          --> "\"         --> current drive absolute
 C:a\b\c.txt         --> "C:"        --> drive relative
 C:\a\b\c.txt        --> "C:\"       --> absolute
 \\server\a\b\c.txt  --> "\\server\" --> UNC

 Unix:
 a/b/c.txt           --> ""          --> relative
 /a/b/c.txt          --> "/"         --> absolute
 ~/a/b/c.txt         --> "~/"        --> current user
 ~                   --> "~/"        --> current user (slash added)
 ~user/a/b/c.txt     --> "~user/"    --> named user
 ~user               --> "~user/"    --> named user (slash added)

      The output will be the same irrespective of the machine that the code is running on. ie. both Unix and Windows prefixes are matched regardless.

      Parameters:
      filename - the filename to find the prefix in, null returns -1
      Returns:
      the length of the prefix, -1 if invalid or null

    • indexOfLastSeparator

      public static int indexOfLastSeparator(String filename)
      Returns the index of the last directory separator character.

      This method will handle a file in either Unix or Windows format. The position of the last forward or backslash is returned.

      The output will be the same irrespective of the machine that the code is running on.

      Parameters:
      filename - the filename to find the last path separator in, null returns -1
      Returns:
      the index of the last separator character, or -1 if there is no such character

    • indexOfExtension

      public static int indexOfExtension(String filename)
      Returns the index of the last extension separator character, which is a dot.

      This method also checks that there is no directory separator after the last dot. To do this it uses indexOfLastSeparator(String) which will handle a file in either Unix or Windows format.

      The output will be the same irrespective of the machine that the code is running on.

      Parameters:
      filename - the filename to find the last path separator in, null returns -1
      Returns:
      the index of the last separator character, or -1 if there is no such character

    • hasExtension

      public static boolean hasExtension(String filename)
      Returns true if file has extension.

    • getPrefix

      public static String getPrefix(String filename)
      Gets the prefix from a full filename, such as C:/ or ~/.

      This method will handle a file in either Unix or Windows format. The prefix includes the first slash in the full filename where applicable. 

      
 Windows:
 a\b\c.txt           --> ""          --> relative
 \a\b\c.txt          --> "\"         --> current drive absolute
 C:a\b\c.txt         --> "C:"        --> drive relative
 C:\a\b\c.txt        --> "C:\"       --> absolute
 \\server\a\b\c.txt  --> "\\server\" --> UNC

 Unix:
 a/b/c.txt           --> ""          --> relative
 /a/b/c.txt          --> "/"         --> absolute
 ~/a/b/c.txt         --> "~/"        --> current user
 ~                   --> "~/"        --> current user (slash added)
 ~user/a/b/c.txt     --> "~user/"    --> named user
 ~user               --> "~user/"    --> named user (slash added)

      The output will be the same irrespective of the machine that the code is running on. ie. both Unix and Windows prefixes are matched regardless.

      Parameters:
      filename - the filename to query, null returns null
      Returns:
      the prefix of the file, null if invalid

    • getPath

      public static String getPath(String filename)
      Gets the path from a full filename, which excludes the prefix.

      This method will handle a file in either Unix or Windows format. The method is entirely text based, and returns the text before and including the last forward or backslash. 

      
 C:\a\b\c.txt --> a\b\
 ~/a/b/c.txt  --> a/b/
 a.txt        --> ""
 a/b/c        --> a/b/
 a/b/c/       --> a/b/c/

      The output will be the same irrespective of the machine that the code is running on.

      This method drops the prefix from the result. See getFullPath(String) for the method that retains the prefix.

      Parameters:
      filename - the filename to query, null returns null
      Returns:
      the path of the file, an empty string if none exists, null if invalid

    • getPathNoEndSeparator

      public static String getPathNoEndSeparator(String filename)
      Gets the path from a full filename, which excludes the prefix, and also excluding the final directory separator.

      This method will handle a file in either Unix or Windows format. The method is entirely text based, and returns the text before the last forward or backslash. 

      
 C:\a\b\c.txt --> a\b
 ~/a/b/c.txt  --> a/b
 a.txt        --> ""
 a/b/c        --> a/b
 a/b/c/       --> a/b/c

      The output will be the same irrespective of the machine that the code is running on.

      This method drops the prefix from the result. See getFullPathNoEndSeparator(String) for the method that retains the prefix.

      Parameters:
      filename - the filename to query, null returns null
      Returns:
      the path of the file, an empty string if none exists, null if invalid

    • doGetPath

      private static String doGetPath(String filename, int separatorAdd)
      Does the work of getting the path.
      Parameters:
      filename - the filename
      separatorAdd - 0 to omit the end separator, 1 to return it
      Returns:
      the path

    • getFullPath

      public static String getFullPath(String filename)
      Gets the full path from a full filename, which is the prefix + path.

      This method will handle a file in either Unix or Windows format. The method is entirely text based, and returns the text before and including the last forward or backslash. 

      
 C:\a\b\c.txt --> C:\a\b\
 ~/a/b/c.txt  --> ~/a/b/
 a.txt        --> ""
 a/b/c        --> a/b/
 a/b/c/       --> a/b/c/
 C:           --> C:
 C:\          --> C:\
 ~            --> ~/
 ~/           --> ~/
 ~user        --> ~user/
 ~user/       --> ~user/

      The output will be the same irrespective of the machine that the code is running on.

      Parameters:
      filename - the filename to query, null returns null
      Returns:
      the path of the file, an empty string if none exists, null if invalid

    • getFullPathNoEndSeparator

      public static String getFullPathNoEndSeparator(String filename)
      Gets the full path from a full filename, which is the prefix + path, and also excluding the final directory separator.

      This method will handle a file in either Unix or Windows format. The method is entirely text based, and returns the text before the last forward or backslash. 

      
 C:\a\b\c.txt --> C:\a\b
 ~/a/b/c.txt  --> ~/a/b
 a.txt        --> ""
 a/b/c        --> a/b
 a/b/c/       --> a/b/c
 C:           --> C:
 C:\          --> C:\
 ~            --> ~
 ~/           --> ~
 ~user        --> ~user
 ~user/       --> ~user

      The output will be the same irrespective of the machine that the code is running on.

      Parameters:
      filename - the filename to query, null returns null
      Returns:
      the path of the file, an empty string if none exists, null if invalid

    • doGetFullPath

      private static String doGetFullPath(String filename, boolean includeSeparator)
      Does the work of getting the path.
      Parameters:
      filename - the filename
      includeSeparator - true to include the end separator
      Returns:
      the path

    • getName

      public static String getName(String filename)
      Gets the name minus the path from a full filename.

      This method will handle a file in either Unix or Windows format. The text after the last forward or backslash is returned. 

      
 a/b/c.txt --> c.txt
 a.txt     --> a.txt
 a/b/c     --> c
 a/b/c/    --> ""

      The output will be the same irrespective of the machine that the code is running on.

      Parameters:
      filename - the filename to query, null returns null
      Returns:
      the name of the file without the path, or an empty string if none exists

    • getBaseName

      public static String getBaseName(String filename)
      Gets the base name, minus the full path and extension, from a full filename.

      This method will handle a file in either Unix or Windows format. The text after the last forward or backslash and before the last dot is returned. 

      
 a/b/c.txt --> c
 a.txt     --> a
 a/b/c     --> c
 a/b/c/    --> ""

      The output will be the same irrespective of the machine that the code is running on.

      Parameters:
      filename - the filename to query, null returns null
      Returns:
      the name of the file without the path, or an empty string if none exists

    • getExtension

      public static String getExtension(String filename)
      Gets the extension of a filename.

      This method returns the textual part of the filename after the last dot. There must be no directory separator after the dot. 

      
 foo.txt      --> "txt"
 a/b/c.jpg    --> "jpg"
 a/b.txt/c    --> ""
 a/b/c        --> ""

      The output will be the same irrespective of the machine that the code is running on.

      Parameters:
      filename - the filename to retrieve the extension of.
      Returns:
      the extension of the file or an empty string if none exists.

    • removeExtension

      public static String removeExtension(String filename)
      Removes the extension from a filename.

      This method returns the textual part of the filename before the last dot. There must be no directory separator after the dot. 

      
 foo.txt    --> foo
 a\b\c.jpg  --> a\b\c
 a\b\c      --> a\b\c
 a.b\c      --> a.b\c

      The output will be the same irrespective of the machine that the code is running on.

      Parameters:
      filename - the filename to query, null returns null
      Returns:
      the filename minus the extension

    • equals

      public static boolean equals(String filename1, String filename2)
      Checks whether two filenames are equal exactly.

    • equalsOnSystem

      public static boolean equalsOnSystem(String filename1, String filename2)
      Checks whether two filenames are equal using the case rules of the system.

    • equals

      private static boolean equals(String filename1, String filename2, boolean system)
      Checks whether two filenames are equal optionally using the case rules of the system.

      Parameters:
      filename1 - the first filename to query, may be null
      filename2 - the second filename to query, may be null
      system - whether to use the system (windows or unix)
      Returns:
      true if the filenames are equal, null equals null

    • split

      public static String[] split(String filename)
      Splits filename into a array of four Strings containing prefix, path, basename and extension. Path will contain ending separator.

    • resolveHome

      public static String resolveHome(String path)
      Resolve ~ in the path.

    • relativePath

      public static String relativePath(String targetPath, String basePath)
      Calculates relative path of target path on base path.