org.apache.poi.util
Class IOUtils

java.lang.Object
  org.apache.poi.util.IOUtils

public final class IOUtils
extends java.lang.Object

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.

Throws:

java.io.IOException

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.

Throws:

java.io.IOException

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)

Throws:

java.io.IOException

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.

Throws:

java.io.IOException

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.

Throws:

java.io.IOException

write

public static void write(POIDocument doc,
                         java.io.OutputStream out)
                  throws java.io.IOException

Write a POI Document (Workbook, SlideShow, etc) to an output stream and close the output stream. This will attempt to close the output stream at the end even if there was a problem writing the document to the stream. If you are using Java 7 or higher, you may prefer to use a try-with-resources statement instead. This function exists for Java 6 code.

Parameters:

doc - a writeable document to write to the output stream

out - the output stream that the document is written to

Throws:

java.io.IOException - thrown on errors writing to the stream

write

public static void write(Workbook doc,
                         java.io.OutputStream out)
                  throws java.io.IOException

Write a (Workbook) to an output stream and close the output stream. This will attempt to close the output stream at the end even if there was a problem writing the document to the stream. If you are using Java 7 or higher, you may prefer to use a try-with-resources statement instead. This function exists for Java 6 code.

Parameters:

doc - a writeable document to write to the output stream

out - the output stream that the document is written to

Throws:

java.io.IOException - thrown on errors writing to the stream

writeAndClose

public static void writeAndClose(POIDocument doc,
                                 java.io.OutputStream out)
                          throws java.io.IOException

Write a POI Document (Workbook, SlideShow, etc) to an output stream and close the output stream. This will attempt to close the output stream at the end even if there was a problem writing the document to the stream. This will also attempt to close the document, even if an error occurred while writing the document or closing the output stream. If you are using Java 7 or higher, you may prefer to use a try-with-resources statement instead. This function exists for Java 6 code.

Parameters:

doc - a writeable and closeable document to write to the output stream, then close

out - the output stream that the document is written to

Throws:

java.io.IOException - thrown on errors writing to the stream

writeAndClose

public static void writeAndClose(POIDocument doc,
                                 java.io.File out)
                          throws java.io.IOException

Like writeAndClose(POIDocument, OutputStream), but for writing to a File instead of an OutputStream. This will attempt to close the document, even if an error occurred while writing the document. If you are using Java 7 or higher, you may prefer to use a try-with-resources statement instead. This function exists for Java 6 code.

Parameters:

doc - a writeable and closeable document to write to the output file, then close

out - the output file that the document is written to

Throws:

java.io.IOException - thrown on errors writing to the stream

writeAndClose

public static void writeAndClose(POIDocument doc)
                          throws java.io.IOException

Like writeAndClose(POIDocument, File), but for writing a POI Document in place (to the same file that it was opened from). This will attempt to close the document, even if an error occurred while writing the document. If you are using Java 7 or higher, you may prefer to use a try-with-resources statement instead. This function exists for Java 6 code.

Parameters:

doc - a writeable document to write in-place

Throws:

java.io.IOException - thrown on errors writing to the file

writeAndClose

public static void writeAndClose(Workbook doc,
                                 java.io.OutputStream out)
                          throws java.io.IOException

Throws:

java.io.IOException

copy

public static void 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.

Throws:

java.io.IOException

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)