AutoCloseable
, Closeable
, DataInput
ImageOutputStream
FileCacheImageInputStream
, FileCacheImageOutputStream
, FileImageInputStream
, FileImageOutputStream
, ImageInputStreamImpl
, ImageOutputStreamImpl
, MemoryCacheImageInputStream
, MemoryCacheImageOutputStream
public interface ImageInputStream extends DataInput, Closeable
ImageReader
s. Various input sources, such as InputStream
s and File
s, as well as future fast I/O sources may be "wrapped" by a suitable implementation of this interface for use by the Image I/O API.Modifier and Type | Method | Description |
---|---|---|
void |
close() |
Closes the stream. |
void |
flush() |
Discards the initial position of the stream prior to the current stream position. |
void |
flushBefore |
Discards the initial portion of the stream prior to the indicated position. |
int |
getBitOffset() |
Returns the current bit offset, as an integer between 0 and 7, inclusive. |
ByteOrder |
getByteOrder() |
Returns the byte order with which data values will be read from this stream as an instance of the java.nio.ByteOrder enumeration. |
long |
getFlushedPosition() |
Returns the earliest position in the stream to which seeking may be performed. |
long |
getStreamPosition() |
Returns the current byte position of the stream. |
boolean |
isCached() |
Returns true if this ImageInputStream caches data itself in order to allow seeking backwards. |
boolean |
isCachedFile() |
Returns true if this ImageInputStream caches data itself in order to allow seeking backwards, and the cache is kept in a temporary file. |
boolean |
isCachedMemory() |
Returns true if this ImageInputStream caches data itself in order to allow seeking backwards, and the cache is kept in main memory. |
long |
length() |
Returns the total length of the stream, if known. |
void |
mark() |
Marks a position in the stream to be returned to by a subsequent call to reset . |
int |
read() |
Reads a single byte from the stream and returns it as an integer between 0 and 255. |
int |
read |
Reads up to b.length bytes from the stream, and stores them into b starting at index 0. |
int |
read |
Reads up to len bytes from the stream, and stores them into b starting at index off . |
int |
readBit() |
Reads a single bit from the stream and returns it as an int with the value 0 or 1 . |
long |
readBits |
Reads a bitstring from the stream and returns it as a long , with the first bit read becoming the most significant bit of the output. |
boolean |
readBoolean() |
Reads a byte from the stream and returns a boolean value of true if it is nonzero, false if it is zero. |
byte |
readByte() |
Reads a byte from the stream and returns it as a byte value. |
void |
readBytes |
Reads up to len bytes from the stream, and modifies the supplied IIOByteBuffer to indicate the byte array, offset, and length where the data may be found. |
char |
readChar() |
Equivalent to readUnsignedShort , except that the result is returned using the char datatype. |
double |
readDouble() |
Reads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as a double . |
float |
readFloat() |
Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as a float . |
void |
readFully |
Reads b.length bytes from the stream, and stores them into b starting at index 0 . |
void |
readFully |
Reads len bytes from the stream, and stores them into b starting at index off . |
void |
readFully |
Reads len chars (unsigned 16-bit integers) from the stream according to the current byte order, and stores them into c starting at index off . |
void |
readFully |
Reads len doubles (64-bit IEEE double-precision floats) from the stream according to the current byte order, and stores them into d starting at index off . |
void |
readFully |
Reads len floats (32-bit IEEE single-precision floats) from the stream according to the current byte order, and stores them into f starting at index off . |
void |
readFully |
Reads len ints (signed 32-bit integers) from the stream according to the current byte order, and stores them into i starting at index off . |
void |
readFully |
Reads len longs (signed 64-bit integers) from the stream according to the current byte order, and stores them into l starting at index off . |
void |
readFully |
Reads len shorts (signed 16-bit integers) from the stream according to the current byte order, and stores them into s starting at index off . |
int |
readInt() |
Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as an int . |
String |
readLine() |
Reads the next line of text from the input stream. |
long |
readLong() |
Reads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as a long . |
short |
readShort() |
Reads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, and returns the result as a short value. |
int |
readUnsignedByte() |
Reads a byte from the stream, and (conceptually) converts it to an int, masks it with 0xff in order to strip off any sign-extension bits, and returns it as a byte value. |
long |
readUnsignedInt() |
Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the result to a long, masks it with 0xffffffffL in order to strip off any sign-extension bits, and returns the result as an unsigned long value. |
int |
readUnsignedShort() |
Reads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the resulting value to an int , masks it with 0xffff in order to strip off any sign-extension buts, and returns the result as an unsigned int value. |
String |
readUTF() |
Reads in a string that has been encoded using a modified UTF-8 format. |
void |
reset() |
Returns the stream pointer to its previous position, including the bit offset, at the time of the most recent unmatched call to mark . |
void |
seek |
Sets the current stream position to the desired location. |
void |
setBitOffset |
Sets the bit offset to an integer between 0 and 7, inclusive. |
void |
setByteOrder |
Sets the desired byte order for future reads of data values from this stream. |
int |
skipBytes |
Moves the stream position forward by a given number of bytes. |
long |
skipBytes |
Moves the stream position forward by a given number of bytes. |
void setByteOrder(ByteOrder byteOrder)
The enumeration class java.nio.ByteOrder
is used to specify the byte order. A value of ByteOrder.BIG_ENDIAN
specifies so-called big-endian or network byte order, in which the high-order byte comes first. Motorola and Sparc processors store data in this format, while Intel processors store data in the reverse ByteOrder.LITTLE_ENDIAN
order.
The byte order has no effect on the results returned from the readBits
method (or the value written by ImageOutputStream.writeBits
).
byteOrder
- one of ByteOrder.BIG_ENDIAN
or java.nio.ByteOrder.LITTLE_ENDIAN
, indicating whether network byte order or its reverse will be used for future reads.ByteOrder getByteOrder()
java.nio.ByteOrder
enumeration.ByteOrder.BIG_ENDIAN
or ByteOrder.LITTLE_ENDIAN
, indicating which byte order is being used.int read() throws IOException
The bit offset within the stream is reset to zero before the read occurs.
IOException
- if an I/O error occurs.int read(byte[] b) throws IOException
b.length
bytes from the stream, and stores them into b
starting at index 0. The number of bytes read is returned. If no bytes can be read because the end of the stream has been reached, -1 is returned. The bit offset within the stream is reset to zero before the read occurs.
b
- an array of bytes to be written to.-1
to indicate EOF.NullPointerException
- if b
is null
.IOException
- if an I/O error occurs.int read(byte[] b, int off, int len) throws IOException
len
bytes from the stream, and stores them into b
starting at index off
. The number of bytes read is returned. If no bytes can be read because the end of the stream has been reached, -1
is returned. The bit offset within the stream is reset to zero before the read occurs.
b
- an array of bytes to be written to.off
- the starting position within b
to write to.len
- the maximum number of byte
s to read.-1
to indicate EOF.NullPointerException
- if b
is null
.IndexOutOfBoundsException
- if off
is negative, len
is negative, or off + len
is greater than b.length
.IOException
- if an I/O error occurs.void readBytes(IIOByteBuffer buf, int len) throws IOException
len
bytes from the stream, and modifies the supplied IIOByteBuffer
to indicate the byte array, offset, and length where the data may be found. The caller should not attempt to modify the data found in the IIOByteBuffer
. The bit offset within the stream is reset to zero before the read occurs.
buf
- an IIOByteBuffer object to be modified.len
- the maximum number of byte
s to read.IndexOutOfBoundsException
- if len
is negative.NullPointerException
- if buf
is null
.IOException
- if an I/O error occurs.boolean readBoolean() throws IOException
boolean
value of true
if it is nonzero, false
if it is zero. The bit offset within the stream is reset to zero before the read occurs.
readBoolean
in interface DataInput
EOFException
- if the end of the stream is reached.IOException
- if an I/O error occurs.byte readByte() throws IOException
byte
value. Byte values between 0x00
and 0x7f
represent integer values between 0
and 127
. Values between 0x80
and 0xff
represent negative values from -128
to /1
. The bit offset within the stream is reset to zero before the read occurs.
readByte
in interface DataInput
EOFException
- if the end of the stream is reached.IOException
- if an I/O error occurs.int readUnsignedByte() throws IOException
0xff
in order to strip off any sign-extension bits, and returns it as a byte
value. Thus, byte values between 0x00
and 0x7f
are simply returned as integer values between 0
and 127
. Values between 0x80
and 0xff
, which normally represent negative byte
values, will be mapped into positive integers between 128
and 255
.
The bit offset within the stream is reset to zero before the read occurs.
readUnsignedByte
in interface DataInput
EOFException
- if the end of the stream is reached.IOException
- if an I/O error occurs.short readShort() throws IOException
short
value. The bit offset within the stream is reset to zero before the read occurs.
readShort
in interface DataInput
EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.int readUnsignedShort() throws IOException
int
, masks it with 0xffff
in order to strip off any sign-extension buts, and returns the result as an unsigned int
value. The bit offset within the stream is reset to zero before the read occurs.
readUnsignedShort
in interface DataInput
EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.char readChar() throws IOException
readUnsignedShort
, except that the result is returned using the char
datatype. The bit offset within the stream is reset to zero before the read occurs.
readChar
in interface DataInput
EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.int readInt() throws IOException
int
. The bit offset within the stream is ignored and treated as though it were zero.
readInt
in interface DataInput
EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.long readUnsignedInt() throws IOException
0xffffffffL
in order to strip off any sign-extension bits, and returns the result as an unsigned long
value. The bit offset within the stream is reset to zero before the read occurs.
EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.long readLong() throws IOException
long
. The bit offset within the stream is reset to zero before the read occurs.
readLong
in interface DataInput
EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.float readFloat() throws IOException
float
. The bit offset within the stream is reset to zero before the read occurs.
readFloat
in interface DataInput
EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.double readDouble() throws IOException
double
. The bit offset within the stream is reset to zero before the read occurs.
readDouble
in interface DataInput
EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.String readLine() throws IOException
String
. Note that because this method processes bytes, it does not support input of the full Unicode character set. If end of file is encountered before even one byte can be read, then null
is returned. Otherwise, each byte that is read is converted to type char
by zero-extension. If the character '\n'
is encountered, it is discarded and reading ceases. If the character '\r'
is encountered, it is discarded and, if the following byte converts to the character '\n'
, then that is discarded also; reading then ceases. If end of file is encountered before either of the characters '\n'
and '\r'
is encountered, reading ceases. Once reading has ceased, a String
is returned that contains all the characters read and not discarded, taken in order. Note that every character in this string will have a value less than \u0100
, that is, (char)256
.
The bit offset within the stream is reset to zero before the read occurs.
readLine
in interface DataInput
IOException
- if an I/O error occurs.String readUTF() throws IOException
readUTF
is that it reads a representation of a Unicode character string encoded in modified UTF-8 format; this string of characters is then returned as a String
. First, two bytes are read and used to construct an unsigned 16-bit integer in the manner of the readUnsignedShort
method, using network byte order (regardless of the current byte order setting). This integer value is called the UTF length and specifies the number of additional bytes to be read. These bytes are then converted to characters by considering them in groups. The length of each group is computed from the value of the first byte of the group. The byte following a group, if any, is the first byte of the next group.
If the first byte of a group matches the bit pattern 0xxxxxxx
(where x
means "may be 0
or 1
"), then the group consists of just that byte. The byte is zero-extended to form a character.
If the first byte of a group matches the bit pattern 110xxxxx
, then the group consists of that byte a
and a second byte b
. If there is no byte b
(because byte a
was the last of the bytes to be read), or if byte b
does not match the bit pattern 10xxxxxx
, then a UTFDataFormatException
is thrown. Otherwise, the group is converted to the character:
(char)(((a& 0x1F) << 6) | (b & 0x3F))
If the first byte of a group matches the bit pattern 1110xxxx
, then the group consists of that byte a
and two more bytes b
and c
. If there is no byte c
(because byte a
was one of the last two of the bytes to be read), or either byte b
or byte c
does not match the bit pattern 10xxxxxx
, then a UTFDataFormatException
is thrown. Otherwise, the group is converted to the character:
(char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F))
If the first byte of a group matches the pattern 1111xxxx
or the pattern 10xxxxxx
, then a UTFDataFormatException
is thrown. If end of file is encountered at any time during this entire process, then a java.io.EOFException
is thrown.
After every group has been converted to a character by this process, the characters are gathered, in the same order in which their corresponding groups were read from the input stream, to form a String
, which is returned.
The current byte order setting is ignored.
The bit offset within the stream is reset to zero before the read occurs.
Note: This method should not be used in the implementation of image formats that use standard UTF-8, because the modified UTF-8 used here is incompatible with standard UTF-8.
readUTF
in interface DataInput
EOFException
- if this stream reaches the end before reading all the bytes.UTFDataFormatException
- if the bytes do not represent a valid modified UTF-8 encoding of a string.IOException
- if an I/O error occurs.void readFully(byte[] b, int off, int len) throws IOException
len
bytes from the stream, and stores them into b
starting at index off
. If the end of the stream is reached, a java.io.EOFException
will be thrown. The bit offset within the stream is reset to zero before the read occurs.
readFully
in interface DataInput
b
- an array of bytes to be written to.off
- the starting position within b
to write to.len
- the maximum number of byte
s to read.IndexOutOfBoundsException
- if off
is negative, len
is negative, or off + len
is greater than b.length
.NullPointerException
- if b
is null
.EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.void readFully(byte[] b) throws IOException
b.length
bytes from the stream, and stores them into b
starting at index 0
. If the end of the stream is reached, a java.io.EOFException
will be thrown. The bit offset within the stream is reset to zero before the read occurs.
readFully
in interface DataInput
b
- an array of byte
s.NullPointerException
- if b
is null
.EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.void readFully(short[] s, int off, int len) throws IOException
len
shorts (signed 16-bit integers) from the stream according to the current byte order, and stores them into s
starting at index off
. If the end of the stream is reached, a java.io.EOFException
will be thrown. The bit offset within the stream is reset to zero before the read occurs.
s
- an array of shorts to be written to.off
- the starting position within s
to write to.len
- the maximum number of short
s to read.IndexOutOfBoundsException
- if off
is negative, len
is negative, or off + len
is greater than s.length
.NullPointerException
- if s
is null
.EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.void readFully(char[] c, int off, int len) throws IOException
len
chars (unsigned 16-bit integers) from the stream according to the current byte order, and stores them into c
starting at index off
. If the end of the stream is reached, a java.io.EOFException
will be thrown. The bit offset within the stream is reset to zero before the read occurs.
c
- an array of chars to be written to.off
- the starting position within c
to write to.len
- the maximum number of char
s to read.IndexOutOfBoundsException
- if off
is negative, len
is negative, or off + len
is greater than c.length
.NullPointerException
- if c
is null
.EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.void readFully(int[] i, int off, int len) throws IOException
len
ints (signed 32-bit integers) from the stream according to the current byte order, and stores them into i
starting at index off
. If the end of the stream is reached, a java.io.EOFException
will be thrown. The bit offset within the stream is reset to zero before the read occurs.
i
- an array of ints to be written to.off
- the starting position within i
to write to.len
- the maximum number of int
s to read.IndexOutOfBoundsException
- if off
is negative, len
is negative, or off + len
is greater than i.length
.NullPointerException
- if i
is null
.EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.void readFully(long[] l, int off, int len) throws IOException
len
longs (signed 64-bit integers) from the stream according to the current byte order, and stores them into l
starting at index off
. If the end of the stream is reached, a java.io.EOFException
will be thrown. The bit offset within the stream is reset to zero before the read occurs.
l
- an array of longs to be written to.off
- the starting position within l
to write to.len
- the maximum number of long
s to read.IndexOutOfBoundsException
- if off
is negative, len
is negative, or off + len
is greater than l.length
.NullPointerException
- if l
is null
.EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.void readFully(float[] f, int off, int len) throws IOException
len
floats (32-bit IEEE single-precision floats) from the stream according to the current byte order, and stores them into f
starting at index off
. If the end of the stream is reached, a java.io.EOFException
will be thrown. The bit offset within the stream is reset to zero before the read occurs.
f
- an array of floats to be written to.off
- the starting position within f
to write to.len
- the maximum number of float
s to read.IndexOutOfBoundsException
- if off
is negative, len
is negative, or off + len
is greater than f.length
.NullPointerException
- if f
is null
.EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.void readFully(double[] d, int off, int len) throws IOException
len
doubles (64-bit IEEE double-precision floats) from the stream according to the current byte order, and stores them into d
starting at index off
. If the end of the stream is reached, a java.io.EOFException
will be thrown. The bit offset within the stream is reset to zero before the read occurs.
d
- an array of doubles to be written to.off
- the starting position within d
to write to.len
- the maximum number of double
s to read.IndexOutOfBoundsException
- if off
is negative, len
is negative, or off + len
is greater than d.length
.NullPointerException
- if d
is null
.EOFException
- if the stream reaches the end before reading all the bytes.IOException
- if an I/O error occurs.long getStreamPosition() throws IOException
IOException
- if an I/O error occurs.int getBitOffset() throws IOException
readBits
method. A value of 0 indicates the most-significant bit, and a value of 7 indicates the least significant bit, of the byte being read. The bit offset is set to 0 when a stream is first opened, and is reset to 0 by calls to seek
, skipBytes
, or any read
or readFully
method.
int
containing the bit offset between 0 and 7, inclusive.IOException
- if an I/O error occurs.void setBitOffset(int bitOffset) throws IOException
getStreamPosition
, is left unchanged. A value of 0 indicates the most-significant bit, and a value of 7 indicates the least significant bit, of the byte being read.bitOffset
- the desired offset, as an int
between 0 and 7, inclusive.IllegalArgumentException
- if bitOffset
is not between 0 and 7, inclusive.IOException
- if an I/O error occurs.int readBit() throws IOException
int
with the value 0
or 1
. The bit offset is advanced by one and reduced modulo 8.int
containing the value 0
or 1
.EOFException
- if the stream reaches the end before reading all the bits.IOException
- if an I/O error occurs.long readBits(int numBits) throws IOException
long
, with the first bit read becoming the most significant bit of the output. The read starts within the byte indicated by getStreamPosition
, at the bit given by getBitOffset
. The bit offset is advanced by numBits
and reduced modulo 8. The byte order of the stream has no effect on this method. The return value of this method is constructed as though the bits were read one at a time, and shifted into the right side of the return value, as shown by the following pseudo-code:
long accum = 0L;
for (int i = 0; i < numBits; i++) {
accum <<= 1; // Shift left one bit to make room
accum |= readBit();
}
Note that the result of readBits(32)
may thus not be equal to that of readInt()
if a reverse network byte order is being used (i.e., getByteOrder() == false
). If the end of the stream is encountered before all the bits have been read, a java.io.EOFException
is thrown.
numBits
- the number of bits to read, as an int
between 0 and 64, inclusive.long
with the last bit read stored in the least significant bit.IllegalArgumentException
- if numBits
is not between 0 and 64, inclusive.EOFException
- if the stream reaches the end before reading all the bits.IOException
- if an I/O error occurs.long length() throws IOException
-1
is returned.long
containing the length of the stream, if known, or else -1
.IOException
- if an I/O error occurs.int skipBytes(int n) throws IOException
skipBytes
in interface DataInput
n
- an int
containing the number of bytes to be skipped.int
representing the number of bytes skipped.IOException
- if an I/O error occurs.long skipBytes(long n) throws IOException
skipBytes(int)
except that it allows for a larger skip distance.n
- a long
containing the number of bytes to be skipped.long
representing the number of bytes skipped.IOException
- if an I/O error occurs.void seek(long pos) throws IOException
An IndexOutOfBoundsException
will be thrown if pos
is smaller than the flushed position (as returned by getflushedPosition
).
It is legal to seek past the end of the file; a java.io.EOFException
will be thrown only if a read is performed.
pos
- a long
containing the desired file pointer position.IndexOutOfBoundsException
- if pos
is smaller than the flushed position.IOException
- if any other I/O error occurs.void mark()
reset
. Unlike a standard InputStream
, all ImageInputStream
s support marking. Additionally, calls to mark
and reset
may be nested arbitrarily. Unlike the mark
methods declared by the Reader
and InputStream
interfaces, no readLimit
parameter is used. An arbitrary amount of data may be read following the call to mark
.
The bit position used by the readBits
method is saved and restored by each pair of calls to mark
and reset
.
Note that it is valid for an ImageReader
to call flushBefore
as part of a read operation. Therefore, if an application calls mark
prior to passing that stream to an ImageReader
, the application should not assume that the marked position will remain valid after the read operation has completed.
void reset() throws IOException
mark
. Calls to reset
without a corresponding call to mark
have no effect.
An IOException
will be thrown if the previous marked position lies in the discarded portion of the stream.
IOException
- if an I/O error occurs.void flushBefore(long pos) throws IOException
IndexOutOfBoundsException
. Calling flushBefore
may allow classes implementing this interface to free up resources such as memory or disk space that are being used to store data from the stream.
pos
- a long
containing the length of the stream prefix that may be flushed.IndexOutOfBoundsException
- if pos
lies in the flushed portion of the stream or past the current stream position.IOException
- if an I/O error occurs.void flush() throws IOException
flushBefore(getStreamPosition())
.IOException
- if an I/O error occurs.long getFlushedPosition()
flushBefore
.long
.boolean isCached()
true
if this ImageInputStream
caches data itself in order to allow seeking backwards. Applications may consult this in order to decide how frequently, or whether, to flush in order to conserve cache resources.true
if this ImageInputStream
caches data.boolean isCachedMemory()
true
if this ImageInputStream
caches data itself in order to allow seeking backwards, and the cache is kept in main memory. Applications may consult this in order to decide how frequently, or whether, to flush in order to conserve cache resources.true
if this ImageInputStream
caches data in main memory.boolean isCachedFile()
true
if this ImageInputStream
caches data itself in order to allow seeking backwards, and the cache is kept in a temporary file. Applications may consult this in order to decide how frequently, or whether, to flush in order to conserve cache resources.true
if this ImageInputStream
caches data in a temporary file.void close() throws IOException
IOException
s or incorrect behavior. Calling this method may allow classes implementing this interface to release resources associated with the stream such as memory, disk space, or file descriptors.close
in interface AutoCloseable
close
in interface Closeable
IOException
- if an I/O error occurs.
© 1993, 2023, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/javax/imageio/stream/ImageInputStream.html