com.helger.commons.io.file

Class FileHelper

java.lang.Object

com.helger.commons.io.file.FileHelper

@Immutable
public final class FileHelper
extends Object

Miscellaneous file utility methods.

Author:

Philip Helger

Method Summary

Modifier and Type	Method and Description
static boolean	canReadAndWriteFile(File aFile) Check if the passed file can read and write.
static EChange	ensureParentDirectoryIsPresent(File aFile)
static boolean	existsDir(File aDir) Check if the passed directory exists.
static boolean	existsFile(File aFile) Check if the passed file exists.
static URL	getAsURL(File aFile)
static String	getAsURLString(File aFile)
static NonBlockingBufferedInputStream	getBufferedInputStream(File aFile)
static NonBlockingBufferedOutputStream	getBufferedOutputStream(File aFile)
static NonBlockingBufferedOutputStream	getBufferedOutputStream(File aFile, EAppend eAppend)
static NonBlockingBufferedReader	getBufferedReader(File aFile, Charset aCharset)
static NonBlockingBufferedWriter	getBufferedWriter(File aFile, Charset aCharset)
static NonBlockingBufferedWriter	getBufferedWriter(File aFile, EAppend eAppend, Charset aCharset)
static File	getCanonicalFile(File aFile) Get the canonical file of the passed file, if the file is not null.
static File	getCanonicalFileOrNull(File aFile) Get the canonical file of the passed file, if the file is not null.
static String	getCanonicalPath(File aFile) Get the canonical path of the passed file, if the file is not null.
static String	getCanonicalPathOrNull(File aFile) Get the canonical path of the passed file, if the file is not null.
static ICommonsList<File>	getDirectoryContent(File aDirectory) This is a replacement for File.listFiles() doing some additional checks on permissions.
static ICommonsList<File>	getDirectoryContent(File aDirectory, FileFilter aFileFilter) This is a replacement for File.listFiles(FileFilter) doing some additional checks on permissions.
static ICommonsList<File>	getDirectoryContent(File aDirectory, FilenameFilter aFilenameFilter) This is a replacement for File.listFiles(FilenameFilter) doing some additional checks on permissions.
static int	getDirectoryObjectCount(File aDirectory) Returns the number of files and directories contained in the passed directory excluding the system internal directories.
static String	getFileSizeDisplay(File aFile)
static String	getFileSizeDisplay(File aFile, int nDecimals)
static String	getFileSizeDisplay(long nFileSize)
static String	getFileSizeDisplay(long nFileSize, int nDecimals)
static FileInputStream	getInputStream(File aFile)
static FileOutputStream	getOutputStream(File aFile) Get an output stream for writing to a file.
static FileOutputStream	getOutputStream(File aFile, EAppend eAppend) Get an output stream for writing to a file.
static PrintWriter	getPrintWriter(File aFile, Charset aCharset)
static PrintWriter	getPrintWriter(File aFile, EAppend eAppend, Charset aCharset)
static RandomAccessFile	getRandomAccessFile(File aFile, ERandomAccessFileMode eMode)
static RandomAccessFile	getRandomAccessFile(String sFilename, ERandomAccessFileMode eMode)
static InputStreamReader	getReader(File aFile, Charset aCharset)
static File	getSecureFile(File aFile) Get a secure File object based on the passed file object.
static OutputStreamWriter	getWriter(File aFile, Charset aCharset)
static OutputStreamWriter	getWriter(File aFile, EAppend eAppend, Charset aCharset)
static boolean	isFileNewer(File aFile1, File aFile2) Returns true if the first file is newer than the second file.
static boolean	isParentDirectory(File aSearchDirectory, File aStartDirectory) Check if the searched directory is a parent object of the start directory

Methods inherited from class java.lang.Object

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

Method Detail

existsFile

public static boolean existsFile(@Nullable
                                 File aFile)

Check if the passed file exists. Must be existing and a file.

Parameters:

aFile - The file to be checked for existence. May be null .

Returns:

true if the passed file is non-null, is a file and exists, false otherwise.

existsDir

public static boolean existsDir(@Nullable
                                File aDir)

Check if the passed directory exists. Must be existing and must be a directory!

Parameters:

aDir - The directory to be checked for existence. May be null.

Returns:

true if the passed directory is not null, is a directory and exists, false otherwise.

canReadAndWriteFile

public static boolean canReadAndWriteFile(@Nullable
                                          File aFile)

Check if the passed file can read and write. If the file already exists, the file itself is checked. If the file does not exist, the parent directory

Parameters:

aFile - The file to be checked. May be null.

Returns:

true if the file can be read and written

ensureParentDirectoryIsPresent

@Nonnull
public static EChange ensureParentDirectoryIsPresent(@Nonnull
                                                               File aFile)

getCanonicalFile

@Nullable
public static File getCanonicalFile(@Nullable
                                               File aFile)
                                        throws IOException

Get the canonical file of the passed file, if the file is not null.

Parameters:

aFile - The file to get the canonical path from. May be null.

Returns:

null if the passed file is null.

Throws:

IOException - If an I/O error occurs, which is possible because the construction of the canonical pathname may require filesystem queries

getCanonicalFileOrNull

@Nullable
public static File getCanonicalFileOrNull(@Nullable
                                                     File aFile)

Get the canonical file of the passed file, if the file is not null. In case of an IOException, null is returned.

Parameters:

aFile - The file to get the canonical path from. May be null.

Returns:

null if the passed file is null or an exception occurred.

getCanonicalPath

@Nullable
public static String getCanonicalPath(@Nullable
                                                 File aFile)
                                          throws IOException

Get the canonical path of the passed file, if the file is not null.

Parameters:

aFile - The file to get the canonical path from. May be null.

Returns:

null if the passed file is null.

Throws:

IOException - If an I/O error occurs, which is possible because the construction of the canonical pathname may require filesystem queries

getCanonicalPathOrNull

@Nullable
public static String getCanonicalPathOrNull(@Nullable
                                                       File aFile)

Get the canonical path of the passed file, if the file is not null. In case of an IOException, null is returned.

Parameters:

aFile - The file to get the canonical path from. May be null.

Returns:

null if the passed file is null.

isParentDirectory

public static boolean isParentDirectory(@Nonnull
                                        File aSearchDirectory,
                                        @Nonnull
                                        File aStartDirectory)

Check if the searched directory is a parent object of the start directory

Parameters:

aSearchDirectory - The directory to be searched. May not be null.

aStartDirectory - The directory where the search starts. May not be null.

Returns:

true if the search directory is a parent of the start directory, false otherwise.

See Also:

getCanonicalFile(File)

getInputStream

@Nullable
public static FileInputStream getInputStream(@Nonnull
                                                        File aFile)

getBufferedInputStream

@Nullable
public static NonBlockingBufferedInputStream getBufferedInputStream(@Nonnull
                                                                               File aFile)

getReader

@Nullable
public static InputStreamReader getReader(@Nonnull
                                                     File aFile,
                                                     @Nonnull
                                                     Charset aCharset)

getBufferedReader

@Nullable
public static NonBlockingBufferedReader getBufferedReader(@Nonnull
                                                                     File aFile,
                                                                     @Nonnull
                                                                     Charset aCharset)

getOutputStream

@Nullable
public static FileOutputStream getOutputStream(@Nonnull
                                                          File aFile)

Get an output stream for writing to a file.

Parameters:

aFile - The file to write to. May not be null.

Returns:

null if the file could not be opened

getOutputStream

@Nullable
public static FileOutputStream getOutputStream(@Nonnull
                                                          File aFile,
                                                          @Nonnull
                                                          EAppend eAppend)

Get an output stream for writing to a file.

Parameters:

aFile - The file to write to. May not be null.

eAppend - Appending mode. May not be null.

Returns:

null if the file could not be opened

getBufferedOutputStream

@Nullable
public static NonBlockingBufferedOutputStream getBufferedOutputStream(@Nonnull
                                                                                 File aFile)

getBufferedOutputStream

@Nullable
public static NonBlockingBufferedOutputStream getBufferedOutputStream(@Nonnull
                                                                                 File aFile,
                                                                                 @Nonnull
                                                                                 EAppend eAppend)

getWriter

@Nullable
public static OutputStreamWriter getWriter(@Nonnull
                                                      File aFile,
                                                      @Nonnull
                                                      Charset aCharset)

getWriter

@Nullable
public static OutputStreamWriter getWriter(@Nonnull
                                                      File aFile,
                                                      @Nonnull
                                                      EAppend eAppend,
                                                      @Nonnull
                                                      Charset aCharset)

getBufferedWriter

@Nullable
public static NonBlockingBufferedWriter getBufferedWriter(@Nonnull
                                                                     File aFile,
                                                                     @Nonnull
                                                                     Charset aCharset)

getBufferedWriter

@Nullable
public static NonBlockingBufferedWriter getBufferedWriter(@Nonnull
                                                                     File aFile,
                                                                     @Nonnull
                                                                     EAppend eAppend,
                                                                     @Nonnull
                                                                     Charset aCharset)

getPrintWriter

@Nullable
public static PrintWriter getPrintWriter(@Nonnull
                                                    File aFile,
                                                    @Nonnull
                                                    Charset aCharset)

getPrintWriter

@Nullable
public static PrintWriter getPrintWriter(@Nonnull
                                                    File aFile,
                                                    @Nonnull
                                                    EAppend eAppend,
                                                    @Nonnull
                                                    Charset aCharset)

getRandomAccessFile

@Nullable
public static RandomAccessFile getRandomAccessFile(@Nonnull
                                                              String sFilename,
                                                              @Nonnull
                                                              ERandomAccessFileMode eMode)

getRandomAccessFile

@Nullable
public static RandomAccessFile getRandomAccessFile(@Nonnull
                                                              File aFile,
                                                              @Nonnull
                                                              ERandomAccessFileMode eMode)

isFileNewer

public static boolean isFileNewer(@Nonnull
                                  File aFile1,
                                  @Nonnull
                                  File aFile2)

Returns true if the first file is newer than the second file. Returns true if the first file exists and the second file does not exist. Returns false if the first file is older than the second file. Returns false if the first file does not exists but the second does. Returns false if none of the files exist.

Parameters:

aFile1 - First file. May not be null.

aFile2 - Second file. May not be null.

Returns:

true if the first file is newer than the second file, false otherwise.

getFileSizeDisplay

@Nonnull
public static String getFileSizeDisplay(@Nullable
                                                  File aFile)

getFileSizeDisplay

@Nonnull
public static String getFileSizeDisplay(@Nullable
                                                  File aFile,
                                                  @Nonnegative
                                                  int nDecimals)

getFileSizeDisplay

@Nonnull
public static String getFileSizeDisplay(long nFileSize)

getFileSizeDisplay

@Nonnull
public static String getFileSizeDisplay(@Nonnegative
                                                  long nFileSize,
                                                  @Nonnegative
                                                  int nDecimals)

getSecureFile

@Nullable
public static File getSecureFile(@Nullable
                                            File aFile)

Get a secure File object based on the passed file object. First all relative paths ("." and "..") are resolved and all eventually contained '\0' characters are eliminated. Than all file names are checked for validity (so that no special characters are contained).

Parameters:

aFile - The file to be secured.

Returns:

null if the passed file is null.

getDirectoryObjectCount

@Nonnegative
public static int getDirectoryObjectCount(@Nonnull
                                                        File aDirectory)

Returns the number of files and directories contained in the passed directory excluding the system internal directories.

Parameters:

aDirectory - The directory to check. May not be null and must be a directory.

Returns:

A non-negative number of objects in that directory.

See Also:

FilenameHelper.isSystemInternalDirectory(CharSequence)

getDirectoryContent

@Nonnull
 @ReturnsMutableCopy
public static ICommonsList<File> getDirectoryContent(@Nonnull
                                                                                     File aDirectory)

This is a replacement for File.listFiles() doing some additional checks on permissions. The order of the returned files is defined by the underlying File.listFiles() method.

Parameters:

aDirectory - The directory to be listed. May not be null.

Returns:

Never null.

getDirectoryContent

@Nonnull
 @ReturnsMutableCopy
public static ICommonsList<File> getDirectoryContent(@Nonnull
                                                                                     File aDirectory,
                                                                                     @Nonnull
                                                                                     FilenameFilter aFilenameFilter)

This is a replacement for File.listFiles(FilenameFilter) doing some additional checks on permissions. The order of the returned files is defined by the underlying File.listFiles(FilenameFilter) method.

Parameters:

aDirectory - The directory to be listed. May not be null.

aFilenameFilter - The filename filter to be used. May not be null.

Returns:

Never null.

getDirectoryContent

@Nonnull
 @ReturnsMutableCopy
public static ICommonsList<File> getDirectoryContent(@Nonnull
                                                                                     File aDirectory,
                                                                                     @Nonnull
                                                                                     FileFilter aFileFilter)

This is a replacement for File.listFiles(FileFilter) doing some additional checks on permissions. The order of the returned files is defined by the underlying File.listFiles(FileFilter) method.

Parameters:

aDirectory - The directory to be listed. May not be null.

aFileFilter - The file filter to be used. May not be null.

Returns:

Never null.

getAsURL

@Nullable
public static URL getAsURL(@Nonnull
                                      File aFile)

getAsURLString

@Nullable
public static String getAsURLString(@Nonnull
                                               File aFile)