ca.uqac.lif.labpal

Class FileHelper

java.lang.Object

ca.uqac.lif.labpal.FileHelper

public class FileHelper
extends java.lang.Object

A number of helpful utilities to read, write and manage files

Author:

Sylvain Hallé

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	CRLF The system-dependent carriage return symbol
static java.lang.String	SLASH The system-dependent symbol for separating paths

Constructor Summary

Constructors

Constructor and Description
FileHelper()

Method Summary

Modifier and Type	Method and Description
static boolean	commandExists(java.lang.String command) Checks if a command exists in the system by attempting to run it
static void	createIfNotExists(java.io.File f) Creates a file and its parent directory if they do not exist
static boolean	deleteFile(java.lang.String filename) Deletes a file
static boolean	fileExists(java.lang.String filename) Checks whether a file exists in the filesystem
static java.util.List<java.lang.String>	getResourceListing(java.lang.Class<?> clazz, java.lang.String path, java.lang.String glob) List directory contents for a resource folder.
static java.util.List<java.lang.String>	getResourceListing(java.lang.Class<?> clazz, java.lang.String path, java.lang.String glob, java.lang.String exclude_glob) List directory contents for a resource folder.
static boolean	internalFileExists(java.lang.Class<?> c, java.lang.String path) Checks if an internal file exists
static byte[]	internalFileToBytes(java.lang.Class<?> c, java.lang.String path) Gets an array of bytes from an internal file
static java.io.InputStream	internalFileToStream(java.lang.Class<?> c, java.lang.String path) Gets an input stream on an internal file
static java.lang.String	internalFileToString(java.lang.Class<?> c, java.lang.String path) Gets a string from an internal file
static java.lang.String	internalFileToString(java.lang.Object o, java.lang.String filename) Gets a string from an internal file
static java.util.List<java.lang.String>	listAllFiles(java.net.URL url, java.lang.String glob) List all files in a folder whose filename matches a regex pattern
static java.util.List<java.lang.String>	listAllInternalFiles(java.lang.Class<?> clazz, java.lang.String directory, java.lang.String glob) List all files in a folder whose filename matches a regex pattern
static byte[]	mergePdf(java.lang.String dest, java.lang.String... paths) Merges multiple PDF files into a single file
static byte[]	readToBytes(java.io.File f) Reads the contents of a file and puts it into an array of bytes.
static java.lang.String	readToString(java.io.File f) Reads the contents of a file and puts it into a string.
static java.lang.String	readToString(java.io.InputStream is) Reads an input stream and puts its contents into a string
static java.lang.String	replaceExtension(java.lang.String filename, java.lang.String extension) Replace the extension of a filename with another.
static java.lang.String	streamToString(java.io.InputStream in) Reads a file and puts its contents in a string
static java.lang.String	trimExtension(java.lang.String filename) Trims the extension of a filename.
static void	writeFromBytes(java.io.File f, byte[] bFile) Writes to a file from an array of bytes
static void	writeFromString(java.io.File f, java.lang.String content) Writes the content of a string to a file

Methods inherited from class java.lang.Object

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

Field Detail

CRLF

public static final transient java.lang.String CRLF

The system-dependent carriage return symbol

SLASH

public static final transient java.lang.String SLASH

The system-dependent symbol for separating paths

Constructor Detail

FileHelper

public FileHelper()

Method Detail

readToString

public static java.lang.String readToString(java.io.File f)

Reads the contents of a file and puts it into a string.

Parameters:

f - The file to read

Returns:

The string with the file's contents, or the empty string if an error occurred.

readToString

public static java.lang.String readToString(java.io.InputStream is)

Reads an input stream and puts its contents into a string

Parameters:

is - The input stream

Returns:

The contents

readToBytes

public static byte[] readToBytes(java.io.File f)

Reads the contents of a file and puts it into an array of bytes.

Parameters:

f - The file to read

Returns:

The array with the file's contents

writeFromString

public static void writeFromString(java.io.File f,
                                   java.lang.String content)

Writes the content of a string to a file

Parameters:

f - The file to write to. If the file does not exist, it will be created

content - The content to write

createIfNotExists

public static void createIfNotExists(java.io.File f)

Creates a file and its parent directory if they do not exist

Parameters:

f - The file to create

writeFromBytes

public static void writeFromBytes(java.io.File f,
                                  byte[] bFile)

Writes to a file from an array of bytes

Parameters:

f - The file to write to. If the file does not exist, it will be created

bFile - The content to write

deleteFile

public static boolean deleteFile(java.lang.String filename)

Deletes a file

Parameters:

filename - The filename

Returns:

true if the file could be deleted, false otherwise

fileExists

public static boolean fileExists(java.lang.String filename)

Checks whether a file exists in the filesystem

Parameters:

filename - The filename to look for

Returns:

true if file exists, false otherwise

replaceExtension

public static java.lang.String replaceExtension(java.lang.String filename,
                                                java.lang.String extension)

Replace the extension of a filename with another. For example, one can replace /my/path/foo.bar with /my/path/foo.baz.

Parameters:

filename - The original filename

extension - The extension to replace with

Returns:

The modified filename

trimExtension

public static java.lang.String trimExtension(java.lang.String filename)

Trims the extension of a filename. For example, with /my/path/foo.bar, would return /my/path/foo

Parameters:

filename - The filename

Returns:

The filename without the extension

internalFileToString

public static java.lang.String internalFileToString(java.lang.Class<?> c,
                                                    java.lang.String path)

Gets a string from an internal file

Parameters:

c - The class used as reference. The path is expressed relative to the location of this class in the project.

path - The path

Returns:

The string, or null if the path does not correspond to a resource

internalFileToBytes

public static byte[] internalFileToBytes(java.lang.Class<?> c,
                                         java.lang.String path)

Gets an array of bytes from an internal file

Parameters:

c - The class used as reference. The path is expressed relative to the location of this class in the project.

path - The path

Returns:

The array of bytes, or null if the path does not correspond to a resource

internalFileToStream

public static java.io.InputStream internalFileToStream(java.lang.Class<?> c,
                                                       java.lang.String path)

Gets an input stream on an internal file

Parameters:

c - The class used as reference. The path is expressed relative to the location of this class in the project.

path - The path

Returns:

An input stream, or null if the path does not correspond to a resource

internalFileExists

public static boolean internalFileExists(java.lang.Class<?> c,
                                         java.lang.String path)

Checks if an internal file exists

Parameters:

c - The reference class

path - The path of the file

Returns:

true if the file exists, false otherwise

streamToString

public static java.lang.String streamToString(java.io.InputStream in)
                                       throws java.io.IOException

Reads a file and puts its contents in a string

Parameters:

in - The input stream to read

Returns:

The file's contents, and empty string if the file does not exist

Throws:

java.io.IOException - If something bad occurs

commandExists

public static boolean commandExists(java.lang.String command)

Checks if a command exists in the system by attempting to run it

Parameters:

command - The command's name

Returns:

true if the command could execute, false otherwise

listAllFiles

public static java.util.List<java.lang.String> listAllFiles(java.net.URL url,
                                                            java.lang.String glob)

List all files in a folder whose filename matches a regex pattern

Parameters:

url - The source folder

glob - The pattern to match

Returns:

The list of file names

listAllInternalFiles

public static java.util.List<java.lang.String> listAllInternalFiles(java.lang.Class<?> clazz,
                                                                    java.lang.String directory,
                                                                    java.lang.String glob)

List all files in a folder whose filename matches a regex pattern

Parameters:

clazz - A class reference

directory - The source folder

glob - The pattern to match

Returns:

The list of file names

getResourceListing

public static java.util.List<java.lang.String> getResourceListing(java.lang.Class<?> clazz,
                                                                  java.lang.String path,
                                                                  java.lang.String glob)

List directory contents for a resource folder. Not recursive. This is basically a brute-force implementation. Works for regular files and also JARs. Original code by Greg Briggs.

Parameters:

clazz - Any java class that lives in the same place as the resources you want.

path - Should end with "/", but not start with one.

glob - The pattern to match

Returns:

Just the name of each member item, not the full paths.

getResourceListing

public static java.util.List<java.lang.String> getResourceListing(java.lang.Class<?> clazz,
                                                                  java.lang.String path,
                                                                  java.lang.String glob,
                                                                  java.lang.String exclude_glob)

List directory contents for a resource folder. Not recursive. This is basically a brute-force implementation. Works for regular files and also JARs. Original code by Greg Briggs.

Parameters:

clazz - Any java class that lives in the same place as the resources you want.

path - Should end with "/", but not start with one.

glob - The pattern to match

exclude_glob - The pattern to exclude files

Returns:

Just the name of each member item, not the full paths.

internalFileToString

public static java.lang.String internalFileToString(java.lang.Object o,
                                                    java.lang.String filename)

Gets a string from an internal file

Parameters:

o - The object used as reference. The path is expressed relative to the location of the object's declaring class in the project.

filename - The path

Returns:

The string, or null if the path does not correspond to a resource or if o is null

mergePdf

public static byte[] mergePdf(java.lang.String dest,
                              java.lang.String... paths)

Merges multiple PDF files into a single file

Parameters:

dest - The destination filename

paths - The input files

Returns:

The array of bytes containing the merged PDF