Package org.apache.poi.util

Class IOUtils

java.lang.Object
org.apache.poi.util.IOUtils
@Internal public final class IOUtils extends Object

  • Method Details

    • 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(InputStream stream) throws 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
      IOException

    • peekFirstNBytes

      public static byte[] peekFirstNBytes(InputStream stream, int limit) throws 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
      IOException

    • toByteArray

      public static byte[] toByteArray(InputStream stream) throws 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:
      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(InputStream stream, int length) throws 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:
      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(InputStream stream, int length, int maxLength) throws 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:
      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(InputStream stream, int maxLength) throws 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:
      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(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(InputStream in, byte[] b) throws 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:
      IOException - if reading from the stream fails

    • readFully

      public static int readFully(InputStream in, byte[] b, int off, int len) throws 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:
      IOException - if reading from the stream fails

    • readFully

      public static int readFully(ReadableByteChannel channel, ByteBuffer b) throws 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:
      IOException - if reading from the stream fails

    • copy

      public static long copy(InputStream inp, OutputStream out) throws 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:
      IOException - If copying the data fails.

    • copy

      public static long copy(InputStream inp, OutputStream out, long limit) throws 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:
      IOException - If copying the data fails.

    • copy

      public static long copy(InputStream srcStream, File destFile) throws 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:
      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(InputStream stream) throws 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:
      IOException

    • closeQuietly

      public static void closeQuietly(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(InputStream input, long toSkip) throws 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:
      IOException - if there is a problem reading the file
      IllegalArgumentException - if toSkip is negative
      See Also:

    • 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(InputStream is) throws 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:
      IOException - on IOException or EOF if -1 is read