org.apache.poi.util

Class IOUtils

java.lang.Object

org.apache.poi.util.IOUtils

@Internal
public final class IOUtils
extends java.lang.Object

Method Summary

Modifier and Type	Method and Description
static long	calculateChecksum(byte[] data) Calculate checksum on input data
static long	calculateChecksum(java.io.InputStream stream) Calculate checksum on all the data read from input stream.
static void	closeQuietly(java.io.Closeable closeable) Quietly (no exceptions) close Closable resource.
static long	copy(java.io.InputStream srcStream, java.io.File destFile) Copy the contents of the stream to a new file.
static long	copy(java.io.InputStream inp, java.io.OutputStream out) Copies all the data from the given InputStream to the OutputStream.
static long	copy(java.io.InputStream inp, java.io.OutputStream out, long limit) Copies all the data from the given InputStream to the OutputStream.
static int	getMaxByteArrayInitSize()
static byte[]	peekFirst8Bytes(java.io.InputStream stream) Peeks at the first 8 bytes of the stream.
static byte[]	peekFirstNBytes(java.io.InputStream stream, int limit) Peeks at the first N bytes of the stream.
static int	readByte(java.io.InputStream is) Simple utility function to check that you haven't hit EOF when reading a byte.
static int	readFully(java.io.InputStream in, byte[] b) Helper method, just calls readFully(in, b, 0, b.length)
static int	readFully(java.io.InputStream in, byte[] b, int off, int len) Same as the normal InputStream.read(byte[], int, int), but tries to ensure that the entire len number of bytes is read.
static int	readFully(java.nio.channels.ReadableByteChannel channel, java.nio.ByteBuffer b) Same as the normal channel.read(b), but tries to ensure that the buffer is filled completely if possible, i.e.
static byte[]	safelyAllocate(long length, int maxLength)
static void	safelyAllocateCheck(long length, int maxLength)
static byte[]	safelyClone(byte[] src, int offset, int length, int maxLength)
static void	setByteArrayMaxOverride(int maxOverride) If this value is set to > 0, safelyAllocate(long, int) will ignore the maximum record length parameter.
static void	setMaxByteArrayInitSize(int maxOverride)
static long	skipFully(java.io.InputStream input, long toSkip) Skips bytes from an input byte stream.
static byte[]	toByteArray(java.nio.ByteBuffer buffer, int length) Returns an array (that shouldn't be written to!) of the ByteBuffer.
static byte[]	toByteArray(java.io.InputStream stream) Reads all the data from the input stream, and returns the bytes read.
static byte[]	toByteArray(java.io.InputStream stream, int length) Reads up to length bytes from the input stream, and returns the bytes read.
static byte[]	toByteArray(java.io.InputStream stream, int length, int maxLength) Reads up to length bytes from the input stream, and returns the bytes read.
static byte[]	toByteArrayWithMaxLength(java.io.InputStream stream, int maxLength) Reads the input stream, and returns the bytes read.

Methods inherited from class java.lang.Object

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

Method Detail

setMaxByteArrayInitSize

public static void setMaxByteArrayInitSize(int maxOverride)

Parameters:

maxOverride - the max init size of ByteArrayOutputStream. -1 (the default) means init size of ByteArrayOutputStream could be up to Integer.MAX_VALUE

Since:

POI 5.2.2

getMaxByteArrayInitSize

public static int getMaxByteArrayInitSize()

Returns:

the max init size of ByteArrayOutputStream. -1 (the default) means init size of ByteArrayOutputStream could be up to Integer.MAX_VALUE

Since:

POI 5.2.2

setByteArrayMaxOverride

public static void setByteArrayMaxOverride(int maxOverride)

If this value is set to > 0, safelyAllocate(long, int) will ignore the maximum record length parameter. This is designed to allow users to bypass the hard-coded maximum record lengths if they are willing to accept the risk of allocating memory up to the size specified. It also allows to impose a lower limit than used for very memory constrained systems. Note: This is a per-allocation limit and does not allow you to limit the overall sum of allocations! Use -1 for using the limits specified per record-type.

Parameters:

maxOverride - The maximum number of bytes that should be possible to be allocated in one step.

Since:

4.0.0

peekFirst8Bytes

public static byte[] peekFirst8Bytes(java.io.InputStream stream)
                              throws java.io.IOException,
                                     EmptyFileException

Peeks at the first 8 bytes of the stream. Returns those bytes, but with the stream unaffected. Requires a stream that supports mark/reset, or a PushbackInputStream. If the stream has >0 but <8 bytes, remaining bytes will be zero.

Throws:

EmptyFileException - if the stream is empty

java.io.IOException

peekFirstNBytes

public static byte[] peekFirstNBytes(java.io.InputStream stream,
                                     int limit)
                              throws java.io.IOException,
                                     EmptyFileException

Peeks at the first N bytes of the stream. Returns those bytes, but with the stream unaffected. Requires a stream that supports mark/reset, or a PushbackInputStream. If the stream has >0 but <N bytes, remaining bytes will be zero.

Throws:

EmptyFileException - if the stream is empty

java.io.IOException

toByteArray

public static byte[] toByteArray(java.io.InputStream stream)
                          throws java.io.IOException

Reads all the data from the input stream, and returns the bytes read.

Parameters:

stream - The byte stream of data to read.

Returns:

A byte array with the read bytes.

Throws:

java.io.IOException - If reading data fails or EOF is encountered too early for the given length.

RecordFormatException - If the requested length is invalid.

toByteArray

public static byte[] toByteArray(java.io.InputStream stream,
                                 int length)
                          throws java.io.IOException

Reads up to length bytes from the input stream, and returns the bytes read.

Parameters:

stream - The byte stream of data to read.

length - The maximum length to read, use Integer.MAX_VALUE to read the stream until EOF.

Returns:

A byte array with the read bytes.

Throws:

java.io.IOException - If reading data fails or EOF is encountered too early for the given length.

RecordFormatException - If the requested length is invalid.

toByteArray

public static byte[] toByteArray(java.io.InputStream stream,
                                 int length,
                                 int maxLength)
                          throws java.io.IOException

Reads up to length bytes from the input stream, and returns the bytes read.

Parameters:

stream - The byte stream of data to read.

length - The maximum length to read, use Integer.MAX_VALUE to read the stream until EOF

maxLength - if the input is equal to/longer than maxLength bytes, then throw an IOException complaining about the length. use Integer.MAX_VALUE to disable the check - if setByteArrayMaxOverride(int) is set then that max of that value and this maxLength is used

Returns:

A byte array with the read bytes.

Throws:

java.io.IOException - If reading data fails or EOF is encountered too early for the given length.

RecordFormatException - If the requested length is invalid.

toByteArrayWithMaxLength

public static byte[] toByteArrayWithMaxLength(java.io.InputStream stream,
                                              int maxLength)
                                       throws java.io.IOException

Reads the input stream, and returns the bytes read.

Parameters:

stream - The byte stream of data to read.

maxLength - if the input is equal to/longer than maxLength bytes, then throw an IOException complaining about the length. use Integer.MAX_VALUE to disable the check - if setByteArrayMaxOverride(int) is set then that max of that value and this maxLength is used

Returns:

A byte array with the read bytes.

Throws:

java.io.IOException - If reading data fails or EOF is encountered too early for the given length.

RecordFormatException - If the requested length is invalid.

Since:

POI 5.2.1

toByteArray

public static byte[] toByteArray(java.nio.ByteBuffer buffer,
                                 int length)

Returns an array (that shouldn't be written to!) of the ByteBuffer. Will be of the requested length, or possibly longer if that's easier.

readFully

public static int readFully(java.io.InputStream in,
                            byte[] b)
                     throws java.io.IOException

Helper method, just calls readFully(in, b, 0, b.length)

Parameters:

in - the stream from which the data is read.

b - the buffer into which the data is read.

Returns:

the number of bytes read or -1 if no bytes were read

Throws:

java.io.IOException - if reading from the stream fails

readFully

public static int readFully(java.io.InputStream in,
                            byte[] b,
                            int off,
                            int len)
                     throws java.io.IOException

Same as the normal InputStream.read(byte[], int, int), but tries to ensure that the entire len number of bytes is read.

If the end of file is reached before any bytes are read, returns -1. If the end of the file is reached after some bytes are read, returns the number of bytes read. If the end of the file isn't reached before len bytes have been read, will return len bytes.

Parameters:

in - the stream from which the data is read.

b - the buffer into which the data is read.

off - the start offset in array b at which the data is written.

len - the maximum number of bytes to read.

Returns:

the number of bytes read or -1 if no bytes were read

Throws:

java.io.IOException - if reading from the stream fails

readFully

public static int readFully(java.nio.channels.ReadableByteChannel channel,
                            java.nio.ByteBuffer b)
                     throws java.io.IOException

Same as the normal channel.read(b), but tries to ensure that the buffer is filled completely if possible, i.e. b.remaining() returns 0.

If the end of file is reached before any bytes are read, returns -1. If the end of the file is reached after some bytes are read, returns the number of bytes read. If the end of the file isn't reached before the buffer has no more remaining capacity, will return the number of bytes that were read.

Parameters:

channel - The byte-channel to read data from

b - the buffer into which the data is read.

Returns:

the number of bytes read or -1 if no bytes were read

Throws:

java.io.IOException - if reading from the stream fails

copy

public static long copy(java.io.InputStream inp,
                        java.io.OutputStream out)
                 throws java.io.IOException

Copies all the data from the given InputStream to the OutputStream. It leaves both streams open, so you will still need to close them once done.

Parameters:

inp - The InputStream which provides the data

out - The OutputStream to write the data to

Returns:

the amount of bytes copied

Throws:

java.io.IOException - If copying the data fails.

copy

public static long copy(java.io.InputStream inp,
                        java.io.OutputStream out,
                        long limit)
                 throws java.io.IOException

Copies all the data from the given InputStream to the OutputStream. It leaves both streams open, so you will still need to close them once done.

Parameters:

inp - The InputStream which provides the data

out - The OutputStream to write the data to

limit - limit the copied bytes - use -1 for no limit

Returns:

the amount of bytes copied

Throws:

java.io.IOException - If copying the data fails.

copy

public static long copy(java.io.InputStream srcStream,
                        java.io.File destFile)
                 throws java.io.IOException

Copy the contents of the stream to a new file.

Parameters:

srcStream - The InputStream which provides the data

destFile - The file where the data should be stored

Returns:

the amount of bytes copied

Throws:

java.io.IOException - If the target directory does not exist and cannot be created or if copying the data fails.

calculateChecksum

public static long calculateChecksum(byte[] data)

Calculate checksum on input data

calculateChecksum

public static long calculateChecksum(java.io.InputStream stream)
                              throws java.io.IOException

Calculate checksum on all the data read from input stream. This should be more efficient than the equivalent code IOUtils.calculateChecksum(IOUtils.toByteArray(stream))

Throws:

java.io.IOException

closeQuietly

public static void closeQuietly(java.io.Closeable closeable)

Quietly (no exceptions) close Closable resource. In case of error it will be printed to IOUtils class logger.

Parameters:

closeable - resource to close

skipFully

public static long skipFully(java.io.InputStream input,
                             long toSkip)
                      throws java.io.IOException

Skips bytes from an input byte stream. This implementation guarantees that it will read as many bytes as possible before giving up; this may not always be the case for skip() implementations in subclasses of InputStream.

Note that the implementation uses InputStream.read(byte[], int, int) rather than delegating to InputStream.skip(long). This means that the method may be considerably less efficient than using the actual skip implementation, this is done to guarantee that the correct number of bytes are skipped.

This mimics POI's readFully(InputStream, byte[]). If the end of file is reached before any bytes are read, returns -1. If the end of the file is reached after some bytes are read, returns the number of bytes read. If the end of the file isn't reached before len bytes have been read, will return len bytes.

Copied nearly verbatim from commons-io 41a3e9c

Parameters:

input - byte stream to skip

toSkip - number of bytes to skip.

Returns:

number of bytes actually skipped.

Throws:

java.io.IOException - if there is a problem reading the file

java.lang.IllegalArgumentException - if toSkip is negative

See Also:

InputStream.skip(long)

safelyAllocate

public static byte[] safelyAllocate(long length,
                                    int maxLength)

safelyAllocateCheck

public static void safelyAllocateCheck(long length,
                                       int maxLength)

safelyClone

public static byte[] safelyClone(byte[] src,
                                 int offset,
                                 int length,
                                 int maxLength)

readByte

public static int readByte(java.io.InputStream is)
                    throws java.io.IOException

Simple utility function to check that you haven't hit EOF when reading a byte.

Parameters:

is - input stream to read

Returns:

byte read, unless

Throws:

java.io.IOException - on IOException or EOF if -1 is read