org.opentrafficsim.base.compressedfiles

Class Reader

java.lang.Object

org.opentrafficsim.base.compressedfiles.Reader

public final class Reader
extends Object

Reader for compressed files.

Copyright (c) 2013-2019 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved.
BSD-style license. See OpenTrafficSim License.

Version:

$Revision$, $LastChangedDate$, by $Author$, initial version Oct 25, 2018

Author:

Alexander Verbraeck, Peter Knoppers, Wouter Schakel

Method Summary

Modifier and Type	Method and Description
static CompressionType	autoDetectCompressionType(String fileName) Determine the type of compression used in a file.
static InputStream	createInputStream(String fileName) Construct a InputStream for a compressed data file.
static InputStream	createInputStream(String fileName, CompressionType compressionType) Construct a InputStream for a compressed data file.
static boolean	isGZipCompressed(byte[] bytes) Determine if bytes match the GZip compression signature.

Methods inherited from class java.lang.Object

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

Method Detail

createInputStream

public static InputStream createInputStream(String fileName,
                                            CompressionType compressionType)
                                     throws IOException

Construct a InputStream for a compressed data file.

Parameters:

fileName - String; the name of the file

compressionType - CompressionType; the expected type of the data compression in the file

Returns:

InputStream that can yield the expanded content of the file.

Throws:

IOException - when the file could not be read

createInputStream

public static InputStream createInputStream(String fileName)
                                     throws IOException

Construct a InputStream for a compressed data file. The type of compression is auto-detected.

Parameters:

fileName - String; the name of the file

Returns:

InputStream that can yield the expanded content of the file.

Throws:

IOException - when the file can not be opened or read

autoDetectCompressionType

public static CompressionType autoDetectCompressionType(String fileName)
                                                 throws IOException

Determine the type of compression used in a file.

Derived from http://stackoverflow.com/questions/4818468/how-to-check-if-inputstream-is-gzipped.
Gzip inflate an inputStream (if it is indeed gzip compressed), otherwise return an InputStream that yields the same data as the input argument.

Parameters:

fileName - String; the name of the file to check

Returns:

InputStream yielding the inflated data

Throws:

IOException - when errors occur reading the signature bytes

isGZipCompressed

public static boolean isGZipCompressed(byte[] bytes)
                                throws IOException

Determine if bytes match the GZip compression signature. Derived from http://stackoverflow.com/questions/4818468/how-to-check-if-inputstream-is-gzipped.
Determines if a byte array is compressed. The java.util.zip GZip implementation does not expose the GZip header so it is difficult to determine if a string is compressed.

Parameters:

bytes - byte[]; at least 2 bytes from the start of the stream to determine compression type

Returns:

boolean; true if the data appears to be GZip compressed; false otherwise

Throws:

IOException - if the byte array couldn't be read