Package org.openjdk.jmc.common.io

Class IOToolkit

java.lang.Object

org.openjdk.jmc.common.io.IOToolkit

public final class IOToolkit
extends Object

Common functionality you might want when you're working with I/O.

Method Summary

Modifier and Type	Method	Description
static String	calculateFileHash(File file)	Calculates an MD5 hash on ten evenly distributed 1kB blocks from the file.
static void	closeSilently(Closeable closeable)	Closes a closeable.
static void	copy(InputStream is, OutputStream os)	Copy all data from an input stream to an output stream.
static void	copy(InputStream is, OutputStream os, int bufferSize)	Copy all data from an input stream to an output stream.
static void	copyFile(File srcFile, File targetFile)	Copies srcFile to targetFile.
static int[]	getGzipMagic()	Returns the magic bytes for identifying Gzip.
static int[]	getLz4Magic()	Returns the magic bytes for identifying LZ4.
static int[]	getZipMagic()	Returns the magic bytes for identifying Zip.
static boolean	hasMagic(File file, int[] magic)	Checks if a file begins with a specified array of bytes.
static boolean	hasMagic(InputStream is, int[] magic)	Checks if an input stream begins with a specified array of bytes.
static boolean	isCompressedFile(File file)	Checks if the file is compressed in a way compatible with openUncompressedStream(File).
static boolean	isGZipFile(File file)	Returns true if the file is GZip file.
static boolean	isLZ4File(File file)	Returns true if the file is LZ4 compressed.
static boolean	isZipFile(File file)	Checks if the file is a ZIP archive.
static List<String>	loadFromFile(File file)	Read lines from a text file.
static List<String>	loadFromStream(InputStream is)	Read lines from an input stream.
static InputStream	openUncompressedStream(File file)	Get an input stream for a optionally compressed file.
static InputStream	openUncompressedStream(InputStream stream)	Get an input stream for a optionally compressed input stream.
static void	saveToFile(File file, List<String> lines)	Write lines to a text file.
static void	write(InputStream in, File toOutput, boolean append)	Copy all data from an input stream to a file.

Methods inherited from class java.lang.Object

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

Method Detail

closeSilently

public static void closeSilently(Closeable closeable)

Closes a closeable. Typically you call this in a final statement so the method also ignores if the closeable is null.

Parameters:

closeable - object to close, may be null

openUncompressedStream

public static InputStream openUncompressedStream(File file)
                                          throws IOException

Get an input stream for a optionally compressed file. If the file is compressed using GZip, ZIP or LZ4, then an appropriate unpacking will be done.

Parameters:

file - file to read from

Returns:

input stream for the unpacked file content

Throws:

IOException - on I/O error

openUncompressedStream

public static InputStream openUncompressedStream(InputStream stream)
                                          throws IOException

Get an input stream for a optionally compressed input stream. If the file is compressed using GZip, ZIP or LZ4, then an appropriate unpacking will be done.

Parameters:

stream - input stream to read from

Returns:

input stream for the unpacked content

Throws:

IOException - on I/O error

hasMagic

public static boolean hasMagic(File file,
                               int[] magic)
                        throws IOException

Checks if a file begins with a specified array of bytes.

Parameters:

file - the file to examine

magic - the magic data, an array with values between 0 and 255

Returns:

true if the file begins with the magic, false otherwise

Throws:

IOException - if an error occurred when trying to read from the file

hasMagic

public static boolean hasMagic(InputStream is,
                               int[] magic)
                        throws IOException

Checks if an input stream begins with a specified array of bytes. The input stream will be positioned at the first byte after the magic data after this call.

Parameters:

is - the input stream to examine

magic - the magic data, an array with values between 0 and 255

Returns:

true if the input stream begins with the magic, false otherwise

Throws:

IOException - if an error occurred when trying to read from the stream

isGZipFile

public static boolean isGZipFile(File file)
                          throws IOException

Returns true if the file is GZip file.

Parameters:

file - the file to examine

Returns:

true if it is a GZip file, false otherwise

Throws:

IOException - if an error occurred when trying to read from the file

isLZ4File

public static boolean isLZ4File(File file)
                         throws IOException

Returns true if the file is LZ4 compressed.

Parameters:

file - the file to examine

Returns:

true if it is an LZ4 compressed file, false otherwise

Throws:

IOException - if an error occurred when trying to read from the file

isZipFile

public static boolean isZipFile(File file)
                         throws IOException

Checks if the file is a ZIP archive.

Parameters:

file - the file to examine

Returns:

true if it's a ZIP archive, false otherwise

Throws:

IOException - if an error occurred when trying to read from the file

getGzipMagic

public static int[] getGzipMagic()

Returns the magic bytes for identifying Gzip. This is a defensive copy. It's up to the user to cache this to avoid excessive allocations.

Returns:

a copy of the magic bytes for Gzip.

getZipMagic

public static int[] getZipMagic()

Returns the magic bytes for identifying Zip. This is a defensive copy. It's up to the user to cache this to avoid excessive allocations.

Returns:

a copy of the magic bytes for Zip.

getLz4Magic

public static int[] getLz4Magic()

Returns the magic bytes for identifying LZ4. This is a defensive copy. It's up to the user to cache this to avoid excessive allocations.

Returns:

a copy of the magic bytes for LZ4.

isCompressedFile

public static boolean isCompressedFile(File file)
                                throws IOException

Checks if the file is compressed in a way compatible with openUncompressedStream(File).

Parameters:

file - the file to examine

Returns:

true if the file is compressed in a manner which can be uncompressed by openUncompressedStream(File), false otherwise

Throws:

IOException - if an error occurred when trying to read from the file

loadFromFile

public static List<String> loadFromFile(File file)
                                 throws IOException

Read lines from a text file.

Parameters:

file - file to read lines from

Returns:

a list of strings, one for each line in the file

Throws:

IOException - on I/O error

See Also:

saveToFile(File, List)

saveToFile

public static void saveToFile(File file,
                              List<String> lines)
                       throws IOException

Write lines to a text file. If the file already exists, it will be overwritten.

Parameters:

file - file to write lines to

lines - a list of strings that will be written on one line each

Throws:

IOException - on I/O error

See Also:

loadFromFile(File)

loadFromStream

public static List<String> loadFromStream(InputStream is)
                                   throws IOException

Read lines from an input stream.

Parameters:

is - input stream to read lines from

Returns:

a list of strings, one for each line in the stream

Throws:

IOException - on I/O error

See Also:

saveToFile(File, List)

write

public static void write(InputStream in,
                         File toOutput,
                         boolean append)
                  throws IOException

Copy all data from an input stream to a file.

Parameters:

in - input stream to read from

toOutput - file to write to

append - true if the file should be appended to, false if it should be overwritten

Throws:

IOException - on I/O error

copy

public static void copy(InputStream is,
                        OutputStream os)
                 throws IOException

Copy all data from an input stream to an output stream.

Parameters:

is - input stream to read from

os - output stream to write to

Throws:

IOException - on I/O error

copy

public static void copy(InputStream is,
                        OutputStream os,
                        int bufferSize)
                 throws IOException

Copy all data from an input stream to an output stream.

Parameters:

is - input stream to read from

os - output stream to write to

bufferSize - size of the buffer used when copying data

Throws:

IOException - on I/O error

copyFile

public static void copyFile(File srcFile,
                            File targetFile)
                     throws IOException

Copies srcFile to targetFile. Will do nothing if srcFile and targetFile are the same file. Will copy file attributes.

Parameters:

srcFile - source file to copy data from

targetFile - target file to copy data to

Throws:

IOException - if something goes wrong during the copy

calculateFileHash

public static String calculateFileHash(File file)
                                throws IOException

Calculates an MD5 hash on ten evenly distributed 1kB blocks from the file.

Parameters:

file - file to calculate hash for

Returns:

MD5 hash string

Throws:

IOException - if something goes wrong when reading file data