| java.lang.Object
 java.io.InputStream
org.apache.xmlgraphics.image.codec.util.SeekableStream
All known Subclasses: org.apache.xmlgraphics.image.codec.util.ForwardSeekableStream, org.apache.xmlgraphics.image.codec.util.FileCacheSeekableStream, org.apache.xmlgraphics.image.codec.util.MemoryCacheSeekableStream,
| SeekableStream | | abstract public class SeekableStream extends InputStream implements DataInput(Code) | | An abstract subclass of java.io.InputStream that allows seeking
within the input, similar to the RandomAccessFile class.
Additionally, the DataInput interface is supported and extended
to include support for little-endian representations of fundamental data
types.
In addition to the familiar methods from InputStream, the
methods getFilePointer(), seek(), are defined as in
the RandomAccessFile class. The canSeekBackwards()
method will return true if it is permissible to seek to a
position earlier in the stream than the current value of
getFilePointer(). Some subclasses of
SeekableStream guarantee the ability to seek backwards while
others may not offer this feature in the interest of providing greater
efficiency for those users who do not require it.
The DataInput interface is supported as well. This included
the skipBytes() and readFully() methods and a
variety of read methods for various data types.
A number of concrete subclasses of SeekableStream are
supplied in the com.sun.media.jai.codec package.
Three classes are provided for the purpose of adapting a standard
InputStream to the SeekableStream interface.
ForwardSeekableStream does not allows seeking backwards, but is
inexpensive to use. FileCacheSeekableStream maintains a copy of
all of the data read from the input in a temporary file; this file will be
discarded automatically when the FileSeekableStream is
finalized, or when the JVM exits normally.
FileCacheSeekableStream is intended to be reasonably efficient
apart from the unavoidable use of disk space. In circumstances where the
creation of a temporary file is not possible,
MemoryCacheSeekableStream may be used.
MemoryCacheSeekableStream creates a potentially large in-memory
buffer to store the stream data and so should be avoided when possible.
The FileSeekableStream class wraps a File or
RandomAccessFile. It forwards requests to the real underlying
file. It performs a limited amount of caching in order to avoid excessive
I/O costs.
The SegmentedSeekableStream class performs a different sort
of function. It creates a SeekableStream from another
SeekableStream by selecting a series of portions or "segments".
Each segment starts at a specified location within the source
SeekableStream and extends for a specified number of bytes. The
StreamSegmentMapper interface and StreamSegment
class may be used to compute the segment positions dynamically.
A convenience methods, wrapInputStream is provided to
construct a suitable SeekableStream instance whose data is
supplied by a given InputStream. The caller, by means of the
canSeekBackwards parameter, determines whether support for
seeking backwards is required.
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| Field Summary | |
| protected long | markPos
|
| Method Summary | |
| public boolean | canSeekBackwards()
Returns true if this object supports calls to
seek(pos) with an offset pos smaller
than the current offset, as returned by getFilePointer. | | protected void | finalize()
Releases any system resources associated with this stream
by calling the close() method. | | abstract public long | getFilePointer()
Returns the current offset in this stream. | | public synchronized void | mark(int readLimit)
Marks the current file position for later return using
the reset() method. | | public boolean | markSupported()
Returns true if marking is supported.
Marking is automatically supported for SeekableStream
subclasses that support seeking backeards. | | abstract public int | read()
Reads the next byte of data from the input stream. | | abstract 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. | | final public boolean | readBoolean()
Reads a boolean from this stream. | | final public byte | readByte()
Reads a signed eight-bit value from this stream. | | final public char | readChar()
Reads a Unicode character from this stream. | | final public char | readCharLE()
Reads a Unicode character from this stream in little-endian order.
This method reads two
bytes from the stream, starting at the current stream pointer. | | final public double | readDouble()
Reads a double from this stream. | | final public double | readDoubleLE()
Reads a double from this stream in little-endian order.
This method reads a
long value, starting at the current stream pointer,
as if by the readLong method
and then converts that long to a double
using the longBitsToDouble method in
class Double.
This method blocks until the eight bytes are read, the end of the
stream is detected, or an exception is thrown. | | final public float | readFloat()
Reads a float from this stream. | | final public float | readFloatLE()
Reads a float from this stream in little-endian order.
This method reads an
int value, starting at the current stream pointer,
as if by the readInt method
and then converts that int to a float
using the intBitsToFloat method in class
Float. | | final public void | readFully(byte[] b)
Reads b.length bytes from this stream into the byte
array, starting at the current stream pointer. | | final public void | readFully(byte[] b, int off, int len)
Reads exactly len bytes from this stream into the byte
array, starting at the current stream pointer. | | final public int | readInt()
Reads a signed 32-bit integer from this stream. | | final public int | readIntLE()
Reads a signed 32-bit integer from this stream in little-endian order.
This method reads 4
bytes from the stream, starting at the current stream pointer. | | final public String | readLine()
Reads the next line of text from this stream. | | final public long | readLong()
Reads a signed 64-bit integer from this stream. | | final public long | readLongLE()
Reads a signed 64-bit integer from this stream in little-endian
order. | | final public short | readShort()
Reads a signed 16-bit number from this stream.
The method reads two
bytes from this stream, starting at the current stream pointer. | | final public short | readShortLE()
Reads a signed 16-bit number from this stream in little-endian order.
The method reads two
bytes from this stream, starting at the current stream pointer. | | final public String | readUTF()
Reads in a string from this stream. | | final public int | readUnsignedByte()
Reads an unsigned eight-bit number from this stream. | | final public long | readUnsignedInt()
Reads an unsigned 32-bit integer from this stream. | | final public long | readUnsignedIntLE()
Reads an unsigned 32-bit integer from this stream in little-endian
order. | | final public int | readUnsignedShort()
Reads an unsigned 16-bit number from this stream. | | final public int | readUnsignedShortLE()
Reads an unsigned 16-bit number from this stream in little-endian order.
This method reads
two bytes from the stream, starting at the current stream pointer. | | public synchronized void | reset()
Returns the file position to its position at the time of
the immediately previous call to the mark()
method. | | abstract public void | seek(long pos)
Sets the offset, measured from the beginning of this
stream, at which the next read occurs. | | public int | skipBytes(int n)
Attempts to skip over n bytes of input discarding the
skipped bytes. | | public static SeekableStream | wrapInputStream(InputStream is, boolean canSeekBackwards)
Returns a SeekableStream that will read from a
given InputStream, optionally including support
for seeking backwards. |
| markPos | | protected long markPos(Code) | | Marked position
|
| canSeekBackwards | | public boolean canSeekBackwards()(Code) | | Returns true if this object supports calls to
seek(pos) with an offset pos smaller
than the current offset, as returned by getFilePointer.
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| finalize | | protected void finalize() throws Throwable(Code) | | Releases any system resources associated with this stream
by calling the close() method.
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| getFilePointer | | abstract public long getFilePointer() throws IOException(Code) | | Returns the current offset in this stream.
the offset from the beginning of the stream, in bytes,at which the next read occurs.
exception:
IOException - if an I/O error occurs. |
| mark | | public synchronized void mark(int readLimit)(Code) | | Marks the current file position for later return using
the reset() method.
|
| markSupported | | public boolean markSupported()(Code) | | Returns true if marking is supported.
Marking is automatically supported for SeekableStream
subclasses that support seeking backeards. Subclasses that do
not support seeking backwards but do support marking must override
this method.
|
| read | | abstract public int read() throws IOException(Code) | | 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. This method
blocks until input data is available, the end of the stream is detected,
or an exception is thrown.
A subclass must provide an implementation of this method.
the next byte of data, or -1 if the end of thestream is reached.
exception:
IOException - if an I/O error occurs. |
| read | | abstract public int read(byte[] b, int off, int len) throws IOException(Code) | | 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.
This method blocks until input data is available, end of stream is
detected, or an exception is thrown.
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
stream, 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
stream, then an IOException is thrown. In particular, an
IOException is thrown if the input stream has been closed.
A subclass must provide an implementation of this method.
Parameters:
b - the buffer into which the data is read.
Parameters:
off - the start offset in array bat which the data is written.
Parameters:
len - the maximum number of bytes to read. the total number of bytes read into the buffer, or-1 if there is no more data because the end ofthe stream has been reached.
exception:
IOException - if an I/O error occurs. |
| readBoolean | | final public boolean readBoolean() throws IOException(Code) | | Reads a boolean from this stream. This method reads a
single byte from the stream, starting at the current stream pointer.
A value of 0 represents
false. Any other value represents true.
This method blocks until the byte is read, the end of the stream
is detected, or an exception is thrown.
the boolean value read.
exception:
EOFException - if this stream has reached the end.
exception:
IOException - if an I/O error occurs. |
| readByte | | final public byte readByte() throws IOException(Code) | | Reads a signed eight-bit value from this stream. This method reads a
byte from the stream, starting from the current stream pointer.
If the byte read is b, where
0 <= b <= 255,
then the result is:
(byte)(b)
This method blocks until the byte is read, the end of the stream
is detected, or an exception is thrown.
the next byte of this stream as a signed eight-bitbyte.
exception:
EOFException - if this stream has reached the end.
exception:
IOException - if an I/O error occurs. |
| readChar | | final public char readChar() throws IOException(Code) | | Reads a Unicode character from this stream. This method reads two
bytes from the stream, starting at the current stream pointer.
If the bytes read, in order, are
b1 and b2, where
0 <= b1, b2 <= 255,
then the result is equal to:
(char)((b1 << 8) | b2)
This method blocks until the two bytes are read, the end of the
stream is detected, or an exception is thrown.
the next two bytes of this stream as a Unicode character.
exception:
EOFException - if this stream reaches the end before readingtwo bytes.
exception:
IOException - if an I/O error occurs. |
| readCharLE | | final public char readCharLE() throws IOException(Code) | | Reads a Unicode character from this stream in little-endian order.
This method reads two
bytes from the stream, starting at the current stream pointer.
If the bytes read, in order, are
b1 and b2, where
0 <= b1, b2 <= 255,
then the result is equal to:
(char)((b2 << 8) | b1)
This method blocks until the two bytes are read, the end of the
stream is detected, or an exception is thrown.
the next two bytes of this stream as a Unicode character.
exception:
EOFException - if this stream reaches the end before readingtwo bytes.
exception:
IOException - if an I/O error occurs. |
| readDouble | | final public double readDouble() throws IOException(Code) | | Reads a double from this stream. This method reads a
long value, starting at the current stream pointer,
as if by the readLong method
and then converts that long to a double
using the longBitsToDouble method in
class Double.
This method blocks until the eight bytes are read, the end of the
stream is detected, or an exception is thrown.
the next eight bytes of this stream, interpreted as adouble.
exception:
EOFException - if this stream reaches the end before readingeight bytes.
exception:
IOException - if an I/O error occurs. |
| readDoubleLE | | final public double readDoubleLE() throws IOException(Code) | | Reads a double from this stream in little-endian order.
This method reads a
long value, starting at the current stream pointer,
as if by the readLong method
and then converts that long to a double
using the longBitsToDouble method in
class Double.
This method blocks until the eight bytes are read, the end of the
stream is detected, or an exception is thrown.
the next eight bytes of this stream, interpreted as adouble.
exception:
EOFException - if this stream reaches the end before readingeight bytes.
exception:
IOException - if an I/O error occurs. |
| readFloat | | final public float readFloat() throws IOException(Code) | | Reads a float from this stream. This method reads an
int value, starting at the current stream pointer,
as if by the readInt method
and then converts that int to a float
using the intBitsToFloat method in class
Float.
This method blocks until the four bytes are read, the end of the
stream is detected, or an exception is thrown.
the next four bytes of this stream, interpreted as afloat.
exception:
EOFException - if this stream reaches the end before readingfour bytes.
exception:
IOException - if an I/O error occurs. |
| readFloatLE | | final public float readFloatLE() throws IOException(Code) | | Reads a float from this stream in little-endian order.
This method reads an
int value, starting at the current stream pointer,
as if by the readInt method
and then converts that int to a float
using the intBitsToFloat method in class
Float.
This method blocks until the four bytes are read, the end of the
stream is detected, or an exception is thrown.
the next four bytes of this stream, interpreted as afloat.
exception:
EOFException - if this stream reaches the end before readingfour bytes.
exception:
IOException - if an I/O error occurs. |
| readFully | | final public void readFully(byte[] b) throws IOException(Code) | | Reads b.length bytes from this stream into the byte
array, starting at the current stream pointer. This method reads
repeatedly from the stream until the requested number of bytes are
read. This method blocks until the requested number of bytes are
read, the end of the stream is detected, or an exception is thrown.
Parameters:
b - the buffer into which the data is read.
exception:
EOFException - if this stream reaches the end before readingall the bytes.
exception:
IOException - if an I/O error occurs. |
| readFully | | final public void readFully(byte[] b, int off, int len) throws IOException(Code) | | Reads exactly len bytes from this stream into the byte
array, starting at the current stream pointer. This method reads
repeatedly from the stream until the requested number of bytes are
read. This method blocks until the requested number of bytes are
read, the end of the stream is detected, or an exception is thrown.
Parameters:
b - the buffer into which the data is read.
Parameters:
off - the start offset of the data.
Parameters:
len - the number of bytes to read.
exception:
EOFException - if this stream reaches the end before readingall the bytes.
exception:
IOException - if an I/O error occurs. |
| readInt | | final public int readInt() throws IOException(Code) | | Reads a signed 32-bit integer from this stream. This method reads 4
bytes from the stream, starting at the current stream pointer.
If the bytes read, in order, are b1,
b2, b3, and b4, where
0 <= b1, b2, b3, b4 <= 255,
then the result is equal to:
(b1 << 24) | (b2 << 16) + (b3 << 8) + b4
This method blocks until the four bytes are read, the end of the
stream is detected, or an exception is thrown.
the next four bytes of this stream, interpreted as anint.
exception:
EOFException - if this stream reaches the end before readingfour bytes.
exception:
IOException - if an I/O error occurs. |
| readIntLE | | final public int readIntLE() throws IOException(Code) | | Reads a signed 32-bit integer from this stream in little-endian order.
This method reads 4
bytes from the stream, starting at the current stream pointer.
If the bytes read, in order, are b1,
b2, b3, and b4, where
0 <= b1, b2, b3, b4 <= 255,
then the result is equal to:
(b4 << 24) | (b3 << 16) + (b2 << 8) + b1
This method blocks until the four bytes are read, the end of the
stream is detected, or an exception is thrown.
the next four bytes of this stream, interpreted as anint.
exception:
EOFException - if this stream reaches the end before readingfour bytes.
exception:
IOException - if an I/O error occurs. |
| readLine | | final public String readLine() throws IOException(Code) | | Reads the next line of text from this stream. This method successively
reads bytes from the stream, starting at the current stream pointer,
until it reaches a line terminator or the end
of the stream. Each byte is converted into a character by taking the
byte's value for the lower eight bits of the character and setting the
high eight bits of the character to zero. This method does not,
therefore, support the full Unicode character set.
A line of text is terminated by a carriage-return character
('\r'), a newline character ('\n'), a
carriage-return character immediately followed by a newline character,
or the end of the stream. Line-terminating characters are discarded and
are not included as part of the string returned.
This method blocks until a newline character is read, a carriage
return and the byte following it are read (to see if it is a newline),
the end of the stream is reached, or an exception is thrown.
the next line of text from this stream, or null if endof stream is encountered before even one byte is read.
exception:
IOException - if an I/O error occurs. |
| readLong | | final public long readLong() throws IOException(Code) | | Reads a signed 64-bit integer from this stream. This method reads eight
bytes from the stream, starting at the current stream pointer.
If the bytes read, in order, are
b1, b2, b3,
b4, b5, b6,
b7, and b8, where:
0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
then the result is equal to:
((long)b1 << 56) + ((long)b2 << 48)
+ ((long)b3 << 40) + ((long)b4 << 32)
+ ((long)b5 << 24) + ((long)b6 << 16)
+ ((long)b7 << 8) + b8
This method blocks until the eight bytes are read, the end of the
stream is detected, or an exception is thrown.
the next eight bytes of this stream, interpreted as along.
exception:
EOFException - if this stream reaches the end before readingeight bytes.
exception:
IOException - if an I/O error occurs. |
| readLongLE | | final public long readLongLE() throws IOException(Code) | | Reads a signed 64-bit integer from this stream in little-endian
order. This method reads eight
bytes from the stream, starting at the current stream pointer.
If the bytes read, in order, are
b1, b2, b3,
b4, b5, b6,
b7, and b8, where:
0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
then the result is equal to:
((long)b1 << 56) + ((long)b2 << 48)
+ ((long)b3 << 40) + ((long)b4 << 32)
+ ((long)b5 << 24) + ((long)b6 << 16)
+ ((long)b7 << 8) + b8
This method blocks until the eight bytes are read, the end of the
stream is detected, or an exception is thrown.
the next eight bytes of this stream, interpreted as along.
exception:
EOFException - if this stream reaches the end before readingeight bytes.
exception:
IOException - if an I/O error occurs. |
| readShort | | final public short readShort() throws IOException(Code) | | Reads a signed 16-bit number from this stream.
The method reads two
bytes from this stream, starting at the current stream pointer.
If the two bytes read, in order, are
b1 and b2, where each of the two values is
between 0 and 255, inclusive, then the
result is equal to:
(short)((b1 << 8) | b2)
This method blocks until the two bytes are read, the end of the
stream is detected, or an exception is thrown.
the next two bytes of this stream, interpreted as a signed16-bit number.
exception:
EOFException - if this stream reaches the end before readingtwo bytes.
exception:
IOException - if an I/O error occurs. |
| readShortLE | | final public short readShortLE() throws IOException(Code) | | Reads a signed 16-bit number from this stream in little-endian order.
The method reads two
bytes from this stream, starting at the current stream pointer.
If the two bytes read, in order, are
b1 and b2, where each of the two values is
between 0 and 255, inclusive, then the
result is equal to:
(short)((b2 << 8) | b1)
This method blocks until the two bytes are read, the end of the
stream is detected, or an exception is thrown.
the next two bytes of this stream, interpreted as a signed16-bit number.
exception:
EOFException - if this stream reaches the end before readingtwo bytes.
exception:
IOException - if an I/O error occurs. |
| readUTF | | final public String readUTF() throws IOException(Code) | | Reads in a string from this stream. The string has been encoded
using a modified UTF-8 format.
The first two bytes are read, starting from the current stream
pointer, as if by
readUnsignedShort. This value gives the number of
following bytes that are in the encoded string, not
the length of the resulting string. The following bytes are then
interpreted as bytes encoding characters in the UTF-8 format
and are converted into characters.
This method blocks until all the bytes are read, the end of the
stream is detected, or an exception is thrown.
a Unicode string.
exception:
EOFException - if this stream reaches the end beforereading all the bytes.
exception:
IOException - if an I/O error occurs.
exception:
UTFDataFormatException - if the bytes do not represent valid UTF-8 encoding of a Unicode string. |
| readUnsignedByte | | final public int readUnsignedByte() throws IOException(Code) | | Reads an unsigned eight-bit number from this stream. This method reads
a byte from this stream, starting at the current stream pointer,
and returns that byte.
This method blocks until the byte is read, the end of the stream
is detected, or an exception is thrown.
the next byte of this stream, interpreted as an unsignedeight-bit number.
exception:
EOFException - if this stream has reached the end.
exception:
IOException - if an I/O error occurs. |
| readUnsignedInt | | final public long readUnsignedInt() throws IOException(Code) | | Reads an unsigned 32-bit integer from this stream. This method reads 4
bytes from the stream, starting at the current stream pointer.
If the bytes read, in order, are b1,
b2, b3, and b4, where
0 <= b1, b2, b3, b4 <= 255,
then the result is equal to:
(b1 << 24) | (b2 << 16) + (b3 << 8) + b4
This method blocks until the four bytes are read, the end of the
stream is detected, or an exception is thrown.
the next four bytes of this stream, interpreted as along.
exception:
EOFException - if this stream reaches the end before readingfour bytes.
exception:
IOException - if an I/O error occurs. |
| readUnsignedIntLE | | final public long readUnsignedIntLE() throws IOException(Code) | | Reads an unsigned 32-bit integer from this stream in little-endian
order. This method reads 4
bytes from the stream, starting at the current stream pointer.
If the bytes read, in order, are b1,
b2, b3, and b4, where
0 <= b1, b2, b3, b4 <= 255,
then the result is equal to:
(b4 << 24) | (b3 << 16) + (b2 << 8) + b1
This method blocks until the four bytes are read, the end of the
stream is detected, or an exception is thrown.
the next four bytes of this stream, interpreted as along.
exception:
EOFException - if this stream reaches the end before readingfour bytes.
exception:
IOException - if an I/O error occurs. |
| readUnsignedShort | | final public int readUnsignedShort() throws IOException(Code) | | Reads an unsigned 16-bit number from this stream. This method reads
two bytes from the stream, starting at the current stream pointer.
If the bytes read, in order, are
b1 and b2, where
0 <= b1, b2 <= 255,
then the result is equal to:
(b1 << 8) | b2
This method blocks until the two bytes are read, the end of the
stream is detected, or an exception is thrown.
the next two bytes of this stream, interpreted as anunsigned 16-bit integer.
exception:
EOFException - if this stream reaches the end before readingtwo bytes.
exception:
IOException - if an I/O error occurs. |
| readUnsignedShortLE | | final public int readUnsignedShortLE() throws IOException(Code) | | Reads an unsigned 16-bit number from this stream in little-endian order.
This method reads
two bytes from the stream, starting at the current stream pointer.
If the bytes read, in order, are
b1 and b2, where
0 <= b1, b2 <= 255,
then the result is equal to:
(b2 << 8) | b1
This method blocks until the two bytes are read, the end of the
stream is detected, or an exception is thrown.
the next two bytes of this stream, interpreted as anunsigned 16-bit integer.
exception:
EOFException - if this stream reaches the end before readingtwo bytes.
exception:
IOException - if an I/O error occurs. |
| reset | | public synchronized void reset() throws IOException(Code) | | Returns the file position to its position at the time of
the immediately previous call to the mark()
method.
|
| seek | | abstract public void seek(long pos) throws IOException(Code) | | Sets the offset, measured from the beginning of this
stream, at which the next read occurs.
If canSeekBackwards() returns false,
then setting pos to an offset smaller than
the current value of getFilePointer() will have
no effect.
Parameters:
pos - the offset position, measured in bytes from the beginning of the stream, at which to set the stream pointer.
exception:
IOException - if pos is less than 0 or if an I/O error occurs. |
| skipBytes | | public int skipBytes(int n) throws IOException(Code) | | Attempts to skip over n bytes of input discarding the
skipped bytes.
This method may skip over some smaller number of bytes, possibly zero.
This may result from any of a number of conditions; reaching end of
stream before n bytes have been skipped is only one
possibility. This method never throws an EOFException.
The actual number of bytes skipped is returned. If n
is negative, no bytes are skipped.
Parameters:
n - the number of bytes to be skipped. the actual number of bytes skipped.
exception:
IOException - if an I/O error occurs. |
| wrapInputStream | | public static SeekableStream wrapInputStream(InputStream is, boolean canSeekBackwards)(Code) | | Returns a SeekableStream that will read from a
given InputStream, optionally including support
for seeking backwards. This is a convenience method that
avoids the need to instantiate specific subclasses of
SeekableStream depending on the current security
model.
Parameters:
is - An InputStream.
Parameters:
canSeekBackwards - true if the ability to seekbackwards in the output is required. An instance of SeekableStream. |
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