DocumentInputStreampublic class DocumentInputStream extends InputStream | This class provides methods to read a DocumentEntry managed by a
Filesystem instance. |
| Fields Summary |
|---|
| private int | _current_offset | | private int | _marked_offset | | private int | _document_size | | private boolean | _closed | | private POIFSDocument | _document | | private byte[] | _tiny_buffer | | private static final int | EOD |
| Constructors Summary |
|---|
public DocumentInputStream(DocumentEntry document)Create an InputStream from the specified DocumentEntry
_current_offset = 0;
_marked_offset = 0;
_document_size = document.getSize();
_closed = false;
_tiny_buffer = null;
if (document instanceof DocumentNode)
{
_document = (( DocumentNode ) document).getDocument();
}
else
{
throw new IOException("Cannot open internal document storage");
}
| public DocumentInputStream(POIFSDocument document)Create an InputStream from the specified Document
_current_offset = 0;
_marked_offset = 0;
_document_size = document.getSize();
_closed = false;
_tiny_buffer = null;
_document = document;
|
| Methods Summary |
|---|
| private boolean | atEOD()
return _current_offset == _document_size;
| | public int | available()Returns the number of bytes that can be read (or skipped over)
from this input stream without blocking by the next caller of a
method for this input stream. The next caller might be the same
thread or or another thread.
dieIfClosed();
return _document_size - _current_offset;
| | public void | close()Closes this input stream and releases any system resources
associated with the stream.
_closed = true;
| | private void | dieIfClosed()
if (_closed)
{
throw new IOException(
"cannot perform requested operation on a closed stream");
}
| | public void | mark(int ignoredReadlimit)Marks the current position in this input stream. A subsequent
call to the reset method repositions this stream at the last
marked position so that subsequent reads re-read the same
bytes.
The readlimit arguments tells this input stream to allow that
many bytes to be read before the mark position gets
invalidated. This implementation, however, does not care.
The general contract of mark is that, if the method
markSupported returns true, the stream somehow remembers all
the bytes read after the call to mark and stands ready to
supply those same bytes again if and whenever the method reset
is called. However, the stream is not required to remember any
data at all if more than readlimit bytes are read from the
stream before reset is called. But this stream will.
_marked_offset = _current_offset;
| | public boolean | markSupported()Tests if this input stream supports the mark and reset methods.
return true;
| | public int | read()Reads the next byte of data from the input stream. The value
byte is returned as an int in the range 0 to 255. If no byte is
available because the end of the stream has been reached, the
value -1 is returned. The definition of this method in
java.io.InputStream allows this method to block, but it won't.
dieIfClosed();
if (atEOD())
{
return EOD;
}
if (_tiny_buffer == null)
{
_tiny_buffer = new byte[ 1 ];
}
_document.read(_tiny_buffer, _current_offset++);
return ((int)_tiny_buffer[ 0 ]) & 0x000000FF;
| | public int | read(byte[] b)Reads some number of bytes from the input stream and stores
them into the buffer array b. The number of bytes actually read
is returned as an integer. The definition of this method in
java.io.InputStream allows this method to block, but it won't.
If b is null, a NullPointerException is thrown. If the length
of b is zero, then no bytes are read and 0 is returned;
otherwise, there is an attempt to read at least one byte. If no
byte is available because the stream is at end of file, the
value -1 is returned; otherwise, at least one byte is read and
stored into b.
The first byte read is stored into element b[0], the next one
into b[1], and so on. The number of bytes read is, at most,
equal to the length of b. Let k be the number of bytes actually
read; these bytes will be stored in elements b[0] through
b[k-1], leaving elements b[k] through b[b.length-1] unaffected.
If the first byte cannot be read for any reason other than end
of file, then an IOException is thrown. In particular, an
IOException is thrown if the input stream has been closed.
The read(b) method for class InputStream has the same effect as:
read(b, 0, b.length)
return read(b, 0, b.length);
| | public int | read(byte[] b, int off, int len)Reads up to len bytes of data from the input stream into an
array of bytes. An attempt is made to read as many as len
bytes, but a smaller number may be read, possibly zero. The
number of bytes actually read is returned as an integer.
The definition of this method in java.io.InputStream allows it
to block, but it won't.
If b is null, a NullPointerException is thrown.
If off is negative, or len is negative, or off+len is greater
than the length of the array b, then an
IndexOutOfBoundsException is thrown.
If len is zero, then no bytes are read and 0 is returned;
otherwise, there is an attempt to read at least one byte. If no
byte is available because the stream is at end of file, the
value -1 is returned; otherwise, at least one byte is read and
stored into b.
The first byte read is stored into element b[off], the next one
into b[off+1], and so on. The number of bytes read is, at most,
equal to len. Let k be the number of bytes actually read; these
bytes will be stored in elements b[off] through b[off+k-1],
leaving elements b[off+k] through b[off+len-1] unaffected.
In every case, elements b[0] through b[off] and elements
b[off+len] through b[b.length-1] are unaffected.
If the first byte cannot be read for any reason other than end
of file, then an IOException is thrown. In particular, an
IOException is thrown if the input stream has been closed.
dieIfClosed();
if (b == null)
{
throw new NullPointerException("buffer is null");
}
if ((off < 0) || (len < 0) || (b.length < (off + len)))
{
throw new IndexOutOfBoundsException(
"can't read past buffer boundaries");
}
if (len == 0)
{
return 0;
}
if (atEOD())
{
return EOD;
}
int limit = Math.min(available(), len);
if ((off == 0) && (limit == b.length))
{
_document.read(b, _current_offset);
}
else
{
byte[] buffer = new byte[ limit ];
_document.read(buffer, _current_offset);
System.arraycopy(buffer, 0, b, off, limit);
}
_current_offset += limit;
return limit;
| | public void | reset()Repositions this stream to the position at the time the mark
method was last called on this input stream.
The general contract of reset is:
-
If the method markSupported returns true, then:
-
If the method mark has not been called since the
stream was created, or the number of bytes read
from the stream since mark was last called is
larger than the argument to mark at that last
call, then an IOException might be thrown.
-
If such an IOException is not thrown, then the
stream is reset to a state such that all the
bytes read since the most recent call to mark
(or since the start of the file, if mark has not
been called) will be resupplied to subsequent
callers of the read method, followed by any
bytes that otherwise would have been the next
input data as of the time of the call to reset.
-
If the method markSupported returns false, then:
-
The call to reset may throw an IOException.
-
If an IOException is not thrown, then the
stream is reset to a fixed state that depends
on the particular type of the input and how it
was created. The bytes that will be supplied to
subsequent callers of the read method depend on
the particular type of the input stream.
All well and good ... this class's markSupported method returns
true and this method does not care whether you've called mark
at all, or whether you've exceeded the number of bytes
specified in the last call to mark. We're basically walking a
byte array ... mark and reset to your heart's content.
_current_offset = _marked_offset;
| | public long | skip(long n)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.
dieIfClosed();
if (n < 0)
{
return 0;
}
int new_offset = _current_offset + ( int ) n;
if (new_offset < _current_offset)
{
// wrap around in converting a VERY large long to an int
new_offset = _document_size;
}
else if (new_offset > _document_size)
{
new_offset = _document_size;
}
long rval = new_offset - _current_offset;
_current_offset = new_offset;
return rval;
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