org.apache.pdfbox.io

Class ByteArrayPushBackInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

java.io.PushbackInputStream

org.apache.pdfbox.io.PushBackInputStream

org.apache.pdfbox.io.ByteArrayPushBackInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class ByteArrayPushBackInputStream
extends PushBackInputStream

PushBackInputStream for byte arrays. The inheritance from PushBackInputStream is only to avoid the introduction of an interface with all PushBackInputStream methods. The parent PushBackInputStream is not used in any way and all methods are overridden. (Thus when adding new methods to PushBackInputStream override them in this class as well!) unread() is limited to the number of bytes already read from this stream (i.e. the current position in the array). This limitation usually poses no problem to a parser, but allows for some optimization since only one array has to be dealt with. Note: This class is not thread safe. Clients must provide synchronization if needed. Note: Calling unread() after mark() will cause (part of) the unread data to be read again after reset(). Thus do not call unread() between mark() and reset().

Version:

$Revision: 1.2 $

Author:

Andreas Weiss (andreas.weiss@switzerland.org)

Field Summary

Fields inherited from class java.io.PushbackInputStream

buf, pos

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor and Description
ByteArrayPushBackInputStream(byte[] input) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
int	available() Available bytes.
boolean	isEOF() A simple test to see if we are at the end of the stream.
int	localRead(byte[] buffer, int off, int len) Read a number of bytes.
void	mark(int readlimit) Save the state of this stream.
boolean	markSupported() Check if mark is supported.
int	peek() This will peek at the next byte.
int	read() Read a byte.
int	read(byte[] buffer) Read a number of bytes.
int	read(byte[] buffer, int off, int len) Read a number of bytes.
void	reset() Restore the state of this stream to the last saveState call.
int	seek(int newpos) Position the stream at a given index.
int	size() Totally available bytes in the underlying array.
long	skip(long num) Skips over and discards n bytes of data from this input stream.
void	unread(byte[] buffer) Pushes back a portion of an array of bytes by copying it to the front of the pushback buffer.
void	unread(byte[] buffer, int off, int len) Pushes back a portion of an array of bytes by copying it to the front of the pushback buffer.
void	unread(int by) Pushes back a byte.

Methods inherited from class org.apache.pdfbox.io.PushBackInputStream

fillBuffer, getOffset, readFully, seek

Methods inherited from class java.io.PushbackInputStream

close

Methods inherited from class java.lang.Object

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

Constructor Detail

ByteArrayPushBackInputStream

public ByteArrayPushBackInputStream(byte[] input)
                             throws IOException

Constructor.

Parameters:

input - Data to read from. Note that calls to unread() will modify this array! If this is not desired, pass a copy.

Throws:

IOException - If there is an IO error.

Method Detail

peek

public int peek()

This will peek at the next byte.

Overrides:

peek in class PushBackInputStream

Returns:

The next byte on the stream, leaving it as available to read.

isEOF

public boolean isEOF()

A simple test to see if we are at the end of the stream.

Overrides:

isEOF in class PushBackInputStream

Returns:

true if we are at the end of the stream.

mark

public void mark(int readlimit)

Save the state of this stream.

Overrides:

mark in class PushbackInputStream

Parameters:

readlimit - Has no effect.

See Also:

InputStream.mark(int)

markSupported

public boolean markSupported()

Check if mark is supported.

Overrides:

markSupported in class PushbackInputStream

Returns:

Always true.

See Also:

InputStream.markSupported()

reset

public void reset()

Restore the state of this stream to the last saveState call.

Overrides:

reset in class PushbackInputStream

See Also:

InputStream.reset()

available

public int available()

Available bytes.

Overrides:

available in class PushbackInputStream

Returns:

Available bytes.

See Also:

InputStream.available()

size

public int size()

Totally available bytes in the underlying array.

Returns:

Available bytes.

unread

public void unread(int by)
            throws IOException

Pushes back a byte. After this method returns, the next byte to be read will have the value (byte)by.

Overrides:

unread in class PushBackInputStream

Parameters:

by - the int value whose low-order byte is to be pushed back.

Throws:

IOException - - If there is not enough room in the buffer for the byte.

See Also:

PushbackInputStream.unread(int)

unread

public void unread(byte[] buffer,
          int off,
          int len)
            throws IOException

Pushes back a portion of an array of bytes by copying it to the front of the pushback buffer. After this method returns, the next byte to be read will have the value b[off], the byte after that will have the value b[off+1], and so forth.

Overrides:

unread in class PushBackInputStream

Parameters:

buffer - the byte array to push back.

off - the start offset of the data.

len - the number of bytes to push back.

Throws:

IOException - If there is not enough room in the pushback buffer for the specified number of bytes.

See Also:

PushbackInputStream.unread(byte[], int, int)

unread

public void unread(byte[] buffer)
            throws IOException

Pushes back a portion of an array of bytes by copying it to the front of the pushback buffer. After this method returns, the next byte to be read will have the value buffer[0], the byte after that will have the value buffer[1], and so forth.

Overrides:

unread in class PushBackInputStream

Parameters:

buffer - the byte array to push back.

Throws:

IOException - If there is not enough room in the pushback buffer for the specified number of bytes.

See Also:

PushbackInputStream.unread(byte[])

read

public int read()

Read a byte.

Overrides:

read in class PushBackInputStream

Returns:

Byte read or -1 if no more bytes are available.

See Also:

InputStream.read()

read

public int read(byte[] buffer)

Read a number of bytes.

Overrides:

read in class PushBackInputStream

Parameters:

buffer - the buffer into which the data is read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

See Also:

InputStream.read(byte[])

read

public int read(byte[] buffer,
       int off,
       int len)

Read a number of bytes.

Overrides:

read in class PushBackInputStream

Parameters:

buffer - the buffer into which the data is read.

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

len - the maximum number of bytes to read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

See Also:

InputStream.read(byte[], int, int)

localRead

public int localRead(byte[] buffer,
            int off,
            int len)

Read a number of bytes. Internal method that assumes off and len to be valid.

Parameters:

buffer - the buffer into which the data is read.

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

len - the maximum number of bytes to read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

See Also:

InputStream.read(byte[], int, int)

skip

public long skip(long num)

Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.

Overrides:

skip in class PushbackInputStream

Parameters:

num - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

See Also:

InputStream.skip(long)

seek

public int seek(int newpos)

Position the stream at a given index. Positioning the stream at position size() will cause the next call to read() to return -1.

Parameters:

newpos - Position in the underlying array. A negative value will be interpreted as 0, a value greater than size() as size().

Returns:

old position.