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	canExecute(File aFile) Tests whether the application can execute the file denoted by this abstract pathname.
static boolean	canRead(File aFile) Tests whether the application can read the file denoted by this abstract pathname.
static boolean	canReadAndWriteFile(File aFile) Check if the passed file can read and write.
static boolean	canWrite(File aFile) Tests whether the application can modify the file denoted by this abstract pathname.
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 Reader	getBufferedReader(File aFile, Charset aCharset)
static Reader	getBufferedReader(String sFilename, Charset aCharset)
static Writer	getBufferedWriter(File aFile, EAppend eAppend, Charset aCharset)
static Writer	getBufferedWriter(String sFilename, 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 List<File>	getDirectoryContent(File aDirectory) This is a replacement for File.listFiles() doing some additional checks on permissions.
static List<File>	getDirectoryContent(File aDirectory, FileFilter aFileFilter) This is a replacement for File.listFiles(FileFilter) doing some additional checks on permissions.
static List<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 FileChannel	getFileReadChannel(File aFile)
static FileChannel	getFileReadChannel(String sFilename)
static long	getFileSize(FileChannel aChannel)
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 FileChannel	getFileWriteChannel(File aFile)
static FileChannel	getFileWriteChannel(File aFile, EAppend eAppend)
static FileChannel	getFileWriteChannel(String sFilename)
static FileChannel	getFileWriteChannel(String sFilename, EAppend eAppend)
static InputStream	getInputStream(File aFile)
static InputStream	getInputStream(String sFilename)
static InputStream	getMappedInputStream(File aFile) Get an input stream to the specified file, using memory mapping.
static OutputStream	getMappedOutputStream(File aFile)
static OutputStream	getMappedOutputStream(File aFile, EAppend eAppend)
static OutputStream	getMappedOutputStream(String sFilename)
static OutputStream	getMappedOutputStream(String sFilename, EAppend eAppend)
static OutputStream	getOutputStream(File aFile) Get an output stream for writing to a file.
static OutputStream	getOutputStream(File aFile, EAppend eAppend) Get an output stream for writing to a file.
static OutputStream	getOutputStream(String sFilename) Get an output stream for writing to a file.
static OutputStream	getOutputStream(String sFilename, EAppend eAppend) Get an output stream for writing to a file.
static RandomAccessFile	getRandomAccessFile(File aFile, ERandomAccessFileMode eMode)
static RandomAccessFile	getRandomAccessFile(String sFilename, ERandomAccessFileMode eMode)
static Reader	getReader(File aFile, Charset aCharset)
static Reader	getReader(String sFilename, Charset aCharset)
static File	getSecureFile(File aFile) Get a secure File object based on the passed file object.
static Writer	getWriter(File aFile, EAppend eAppend, Charset aCharset)
static Writer	getWriter(String sFilename, 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.

canRead

public static boolean canRead(@Nullable
                              File aFile)

Tests whether the application can read the file denoted by this abstract pathname.

Parameters:

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

Returns:

true if and only if the file specified by this abstract pathname is not null, exists and can be read by the application; false otherwise

canWrite

public static boolean canWrite(@Nullable
                               File aFile)

Tests whether the application can modify the file denoted by this abstract pathname.

Parameters:

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

Returns:

true if and only if the parameter is not null, the file system actually contains a file denoted by this abstract pathname and the application is allowed to write to the file; false otherwise.

canExecute

public static boolean canExecute(@Nullable
                                 File aFile)

Tests whether the application can execute the file denoted by this abstract pathname.

Parameters:

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

Returns:

true if and only if the abstract pathname is not null, exists and the application is allowed to execute the file

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)

getFileReadChannel

@Nullable
public static FileChannel getFileReadChannel(@Nonnull
                                                        String sFilename)

getFileReadChannel

@Nullable
public static FileChannel getFileReadChannel(@Nonnull
                                                        File aFile)

getFileSize

@CheckForSigned
public static long getFileSize(@Nonnull @WillNotClose
                                                FileChannel aChannel)

getInputStream

@Nullable
public static InputStream getInputStream(@Nonnull
                                                    String sFilename)

getInputStream

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

getReader

@Nullable
public static Reader getReader(@Nonnull
                                          String sFilename,
                                          @Nonnull
                                          Charset aCharset)

getReader

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

getBufferedReader

@Nullable
public static Reader getBufferedReader(@Nonnull
                                                  String sFilename,
                                                  @Nonnull
                                                  Charset aCharset)

getBufferedReader

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

getMappedInputStream

@Nullable
public static InputStream getMappedInputStream(@Nonnull
                                                          File aFile)

Get an input stream to the specified file, using memory mapping. If memory mapping fails, a regular FileInputStream is returned.

Parameters:

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

Returns:

The Input stream to use.

getFileWriteChannel

@Nullable
public static FileChannel getFileWriteChannel(@Nonnull
                                                         String sFilename)

getFileWriteChannel

@Nullable
public static FileChannel getFileWriteChannel(@Nonnull
                                                         String sFilename,
                                                         @Nonnull
                                                         EAppend eAppend)

getFileWriteChannel

@Nullable
public static FileChannel getFileWriteChannel(@Nonnull
                                                         File aFile)

getFileWriteChannel

@Nullable
public static FileChannel getFileWriteChannel(@Nonnull
                                                         File aFile,
                                                         @Nonnull
                                                         EAppend eAppend)

getOutputStream

@Nullable
public static OutputStream getOutputStream(@Nonnull
                                                      String sFilename)

Get an output stream for writing to a file. Any existing file is overwritten.

Parameters:

sFilename - The name of the file to write to. May not be null.

Returns:

null if the file could not be opened

getOutputStream

@Nullable
public static OutputStream getOutputStream(@Nonnull
                                                      String sFilename,
                                                      @Nonnull
                                                      EAppend eAppend)

Get an output stream for writing to a file.

Parameters:

sFilename - The name of 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

getOutputStream

@Nullable
public static OutputStream 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

getWriter

@Nullable
public static Writer getWriter(@Nonnull
                                          String sFilename,
                                          @Nonnull
                                          EAppend eAppend,
                                          @Nonnull
                                          Charset aCharset)

getWriter

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

getBufferedWriter

@Nullable
public static Writer getBufferedWriter(@Nonnull
                                                  String sFilename,
                                                  @Nonnull
                                                  EAppend eAppend,
                                                  @Nonnull
                                                  Charset aCharset)

getBufferedWriter

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

getOutputStream

@Nullable
public static OutputStream 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

getMappedOutputStream

@Nullable
public static OutputStream getMappedOutputStream(@Nonnull
                                                            String sFilename)

getMappedOutputStream

@Nullable
public static OutputStream getMappedOutputStream(@Nonnull
                                                            String sFilename,
                                                            @Nonnull
                                                            EAppend eAppend)

getMappedOutputStream

@Nullable
public static OutputStream getMappedOutputStream(@Nonnull
                                                            File aFile)

getMappedOutputStream

@Nullable
public static OutputStream getMappedOutputStream(@Nonnull
                                                            File aFile,
                                                            @Nonnull
                                                            EAppend eAppend)

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 List<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 List<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 List<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)