IOUtils (POI API Documentation)

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

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

Method Summary

All Methods Static Methods Concrete Methods
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 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 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.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - 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 an per-allocation limit and does not allow to limit 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.
  - 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.
  - 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
    
    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.
  - 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
  - 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 - inputstream to read
    
    Returns:
    
    byte read, unless
    
    Throws:
    
    java.io.IOException - on IOException or EOF if -1 is read

Class IOUtils

Method Summary

Methods inherited from class java.lang.Object

Method Detail

setByteArrayMaxOverride

peekFirst8Bytes

peekFirstNBytes

toByteArray

toByteArray

toByteArray

toByteArray

readFully

readFully

readFully

copy

copy

copy

calculateChecksum

calculateChecksum

closeQuietly

skipFully

safelyAllocate

safelyAllocateCheck

safelyClone

readByte