org.pdfbox.io

Class ByteArrayPushBackInputStream


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)

Constructor Summary

ByteArrayPushBackInputStream(byte[] input)
Constructor.

Method Summary

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.pdfbox.io.PushBackInputStream

fillBuffer, isEOF, peek

Constructor Details

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.

Method Details

available

public int available()
Available bytes.
Returns:
Available bytes.
See Also:
InputStream.available()

isEOF

public boolean isEOF()
A simple test to see if we are at the end of the stream.
Overrides:
isEOF in interface PushBackInputStream
Returns:
true if we are at the end of the stream.

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)

mark

public void mark(int readlimit)
Save the state of this stream.
Parameters:
readlimit - Has no effect.
See Also:
InputStream.mark(int)

markSupported

public boolean markSupported()
Check if mark is supported.
Returns:
Always true.
See Also:
InputStream.markSupported()

peek

public int peek()
This will peek at the next byte.
Overrides:
peek in interface PushBackInputStream
Returns:
The next byte on the stream, leaving it as available to read.

read

public int read()
Read a byte.
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.
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.
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)

reset

public void reset()
Restore the state of this stream to the last saveState call.
See Also:
InputStream.reset()

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.

size

public int size()
Totally available bytes in the underlying array.
Returns:
Available bytes.

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.
Parameters:
num - the number of bytes to be skipped.
Returns:
the actual number of bytes skipped.
See Also:
InputStream.skip(long)

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.
Parameters:
buffer - the byte array to push back.
See Also:
java.io.PushbackInputStream.unread(byte[])

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.
Parameters:
buffer - the byte array to push back.
off - the start offset of the data.
len - the number of bytes to push back.
See Also:
java.io.PushbackInputStream.unread(byte[], int, int)

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.
Parameters:
by - the int value whose low-order byte is to be pushed back.
See Also:
java.io.PushbackInputStream.unread(int)