Class ImageInputStreamImpl
- All Implemented Interfaces:
Closeable,DataInput,AutoCloseable,ImageInputStream
- Direct Known Subclasses:
FileCacheImageInputStream,FileImageInputStream,ImageOutputStreamImpl,MemoryCacheImageInputStream
ImageInputStream interface.
This class is designed to reduce the number of methods that must
be implemented by subclasses.
In particular, this class handles most or all of the details of byte order interpretation, buffering, mark/reset, discarding, closing, and disposing.
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected intThe current bit offset within the stream.protected ByteOrderThe byte order of the stream as an instance of the enumeration classjava.nio.ByteOrder, whereByteOrder.BIG_ENDIANindicates network byte order andByteOrder.LITTLE_ENDIANindicates the reverse order.protected longThe position prior to which data may be discarded.protected longThe current read position within the stream. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected final voidThrows anIOExceptionif the stream has been closed.voidclose()Closes the stream.protected voidfinalize()Deprecated, for removal: This API element is subject to removal in a future version.Finalization has been deprecated for removal.voidflush()Discards the initial position of the stream prior to the current stream position.voidflushBefore(long pos) Discards the initial portion of the stream prior to the indicated position.intReturns the current bit offset, as an integer between 0 and 7, inclusive.Returns the byte order with which data values will be read from this stream as an instance of thejava.nio.ByteOrderenumeration.longReturns the earliest position in the stream to which seeking may be performed.longReturns the current byte position of the stream.booleanisCached()Default implementation returns false.booleanDefault implementation returns false.booleanDefault implementation returns false.longlength()Returns-1Lto indicate that the stream has unknown length.voidmark()Pushes the current stream position onto a stack of marked positions.abstract intread()Reads a single byte from the stream and returns it as anintbetween 0 and 255.intread(byte[] b) A convenience method that callsread(b, 0, b.length).abstract intread(byte[] b, int off, int len) Reads up tolenbytes from the stream, and stores them intobstarting at indexoff.intreadBit()Reads a single bit from the stream and returns it as anintwith the value0or1.longreadBits(int numBits) Reads a bitstring from the stream and returns it as along, with the first bit read becoming the most significant bit of the output.booleanReads a byte from the stream and returns abooleanvalue oftrueif it is nonzero,falseif it is zero.bytereadByte()Reads a byte from the stream and returns it as abytevalue.voidreadBytes(IIOByteBuffer buf, int len) Reads up tolenbytes from the stream, and modifies the suppliedIIOByteBufferto indicate the byte array, offset, and length where the data may be found.charreadChar()Equivalent toreadUnsignedShort, except that the result is returned using thechardatatype.doubleReads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as adouble.floatReads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as afloat.voidreadFully(byte[] b) Readsb.lengthbytes from the stream, and stores them intobstarting at index0.voidreadFully(byte[] b, int off, int len) Readslenbytes from the stream, and stores them intobstarting at indexoff.voidreadFully(char[] c, int off, int len) Readslenchars (unsigned 16-bit integers) from the stream according to the current byte order, and stores them intocstarting at indexoff.voidreadFully(double[] d, int off, int len) Readslendoubles (64-bit IEEE double-precision floats) from the stream according to the current byte order, and stores them intodstarting at indexoff.voidreadFully(float[] f, int off, int len) Readslenfloats (32-bit IEEE single-precision floats) from the stream according to the current byte order, and stores them intofstarting at indexoff.voidreadFully(int[] i, int off, int len) Readslenints (signed 32-bit integers) from the stream according to the current byte order, and stores them intoistarting at indexoff.voidreadFully(long[] l, int off, int len) Readslenlongs (signed 64-bit integers) from the stream according to the current byte order, and stores them intolstarting at indexoff.voidreadFully(short[] s, int off, int len) Readslenshorts (signed 16-bit integers) from the stream according to the current byte order, and stores them intosstarting at indexoff.intreadInt()Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as anint.readLine()Reads the next line of text from the input stream.longreadLong()Reads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as along.shortReads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, and returns the result as ashortvalue.intReads a byte from the stream, and (conceptually) converts it to an int, masks it with0xffin order to strip off any sign-extension bits, and returns it as abytevalue.longReads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the result to a long, masks it with0xffffffffLin order to strip off any sign-extension bits, and returns the result as an unsignedlongvalue.intReads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the resulting value to anint, masks it with0xffffin order to strip off any sign-extension buts, and returns the result as an unsignedintvalue.readUTF()Reads in a string that has been encoded using a modified UTF-8 format.voidreset()Resets the current stream byte and bit positions from the stack of marked positions.voidseek(long pos) Sets the current stream position to the desired location.voidsetBitOffset(int bitOffset) Sets the bit offset to an integer between 0 and 7, inclusive.voidsetByteOrder(ByteOrder byteOrder) Sets the desired byte order for future reads of data values from this stream.intskipBytes(int n) Advances the current stream position by callingseek(getStreamPosition() + n).longskipBytes(long n) Advances the current stream position by callingseek(getStreamPosition() + n).
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Field Details
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byteOrder
The byte order of the stream as an instance of the enumeration classjava.nio.ByteOrder, whereByteOrder.BIG_ENDIANindicates network byte order andByteOrder.LITTLE_ENDIANindicates the reverse order. By default, the value isByteOrder.BIG_ENDIAN. -
streamPos
protected long streamPosThe current read position within the stream. Subclasses are responsible for keeping this value current from any method they override that alters the read position. -
bitOffset
protected int bitOffsetThe current bit offset within the stream. Subclasses are responsible for keeping this value current from any method they override that alters the bit offset. -
flushedPos
protected long flushedPosThe position prior to which data may be discarded. Seeking to a smaller position is not allowed.flushedPoswill always be >= 0.
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Constructor Details
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ImageInputStreamImpl
public ImageInputStreamImpl()Constructs anImageInputStreamImpl.
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Method Details
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checkClosed
Throws anIOExceptionif the stream has been closed. Subclasses may call this method from any of their methods that require the stream not to be closed.- Throws:
IOException- if the stream is closed.
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setByteOrder
Description copied from interface:ImageInputStreamSets the desired byte order for future reads of data values from this stream. For example, the sequence of bytes '0x01 0x02 0x03 0x04' if read as a 4-byte integer would have the value '0x01020304' using network byte order and the value '0x04030201' under the reverse byte order.The enumeration class
java.nio.ByteOrderis used to specify the byte order. A value ofByteOrder.BIG_ENDIANspecifies 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 reverseByteOrder.LITTLE_ENDIANorder.The byte order has no effect on the results returned from the
readBitsmethod (or the value written byImageOutputStream.writeBits).- Specified by:
setByteOrderin interfaceImageInputStream- Parameters:
byteOrder- one ofByteOrder.BIG_ENDIANorjava.nio.ByteOrder.LITTLE_ENDIAN, indicating whether network byte order or its reverse will be used for future reads.- See Also:
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getByteOrder
Description copied from interface:ImageInputStreamReturns the byte order with which data values will be read from this stream as an instance of thejava.nio.ByteOrderenumeration.- Specified by:
getByteOrderin interfaceImageInputStream- Returns:
- one of
ByteOrder.BIG_ENDIANorByteOrder.LITTLE_ENDIAN, indicating which byte order is being used. - See Also:
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read
Reads a single byte from the stream and returns it as anintbetween 0 and 255. If EOF is reached,-1is returned.Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.
The bit offset within the stream must be reset to zero before the read occurs.
- Specified by:
readin interfaceImageInputStream- Returns:
- the value of the next byte in the stream, or
-1if EOF is reached. - Throws:
IOException- if the stream has been closed.
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read
A convenience method that callsread(b, 0, b.length).The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readin interfaceImageInputStream- Parameters:
b- an array of bytes to be written to.- Returns:
- the number of bytes actually read, or
-1to indicate EOF. - Throws:
NullPointerException- ifbisnull.IOException- if an I/O error occurs.
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read
Reads up tolenbytes from the stream, and stores them intobstarting at indexoff. If no bytes can be read because the end of the stream has been reached,-1is returned.The bit offset within the stream must be reset to zero before the read occurs.
Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.
- Specified by:
readin interfaceImageInputStream- Parameters:
b- an array of bytes to be written to.off- the starting position withinbto write to.len- the maximum number of bytes to read.- Returns:
- the number of bytes actually read, or
-1to indicate EOF. - Throws:
IndexOutOfBoundsException- ifoffis negative,lenis negative, oroff + lenis greater thanb.length.NullPointerException- ifbisnull.IOException- if an I/O error occurs.
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readBytes
Description copied from interface:ImageInputStreamReads up tolenbytes from the stream, and modifies the suppliedIIOByteBufferto indicate the byte array, offset, and length where the data may be found. The caller should not attempt to modify the data found in theIIOByteBuffer.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readBytesin interfaceImageInputStream- Parameters:
buf- an IIOByteBuffer object to be modified.len- the maximum number ofbytes to read.- Throws:
IOException- if an I/O error occurs.
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readBoolean
Description copied from interface:ImageInputStreamReads a byte from the stream and returns abooleanvalue oftrueif it is nonzero,falseif it is zero.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readBooleanin interfaceDataInput- Specified by:
readBooleanin interfaceImageInputStream- Returns:
- a boolean value from the stream.
- Throws:
EOFException- if the end of the stream is reached.IOException- if an I/O error occurs.
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readByte
Description copied from interface:ImageInputStreamReads a byte from the stream and returns it as abytevalue. Byte values between0x00and0x7frepresent integer values between0and127. Values between0x80and0xffrepresent negative values from-128to/1.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readBytein interfaceDataInput- Specified by:
readBytein interfaceImageInputStream- Returns:
- a signed byte value from the stream.
- Throws:
EOFException- if the end of the stream is reached.IOException- if an I/O error occurs.
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readUnsignedByte
Description copied from interface:ImageInputStreamReads a byte from the stream, and (conceptually) converts it to an int, masks it with0xffin order to strip off any sign-extension bits, and returns it as abytevalue.Thus, byte values between
0x00and0x7fare simply returned as integer values between0and127. Values between0x80and0xff, which normally represent negativebytevalues, will be mapped into positive integers between128and255.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readUnsignedBytein interfaceDataInput- Specified by:
readUnsignedBytein interfaceImageInputStream- Returns:
- an unsigned byte value from the stream.
- Throws:
EOFException- if the end of the stream is reached.IOException- if an I/O error occurs.
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readShort
Description copied from interface:ImageInputStreamReads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, and returns the result as ashortvalue.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readShortin interfaceDataInput- Specified by:
readShortin interfaceImageInputStream- Returns:
- a signed short value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readUnsignedShort
Description copied from interface:ImageInputStreamReads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the resulting value to anint, masks it with0xffffin order to strip off any sign-extension buts, and returns the result as an unsignedintvalue.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readUnsignedShortin interfaceDataInput- Specified by:
readUnsignedShortin interfaceImageInputStream- Returns:
- an unsigned short value from the stream, as an int.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readChar
Description copied from interface:ImageInputStreamEquivalent toreadUnsignedShort, except that the result is returned using thechardatatype.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readCharin interfaceDataInput- Specified by:
readCharin interfaceImageInputStream- Returns:
- an unsigned char value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readInt
Description copied from interface:ImageInputStreamReads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as anint.The bit offset within the stream is ignored and treated as though it were zero.
- Specified by:
readIntin interfaceDataInput- Specified by:
readIntin interfaceImageInputStream- Returns:
- a signed int value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readUnsignedInt
Description copied from interface:ImageInputStreamReads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the result to a long, masks it with0xffffffffLin order to strip off any sign-extension bits, and returns the result as an unsignedlongvalue.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readUnsignedIntin interfaceImageInputStream- Returns:
- an unsigned int value from the stream, as a long.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readLong
Description copied from interface:ImageInputStreamReads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as along.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readLongin interfaceDataInput- Specified by:
readLongin interfaceImageInputStream- Returns:
- a signed long value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readFloat
Description copied from interface:ImageInputStreamReads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as afloat.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFloatin interfaceDataInput- Specified by:
readFloatin interfaceImageInputStream- Returns:
- a float value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readDouble
Description copied from interface:ImageInputStreamReads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as adouble.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readDoublein interfaceDataInput- Specified by:
readDoublein interfaceImageInputStream- Returns:
- a double value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readLine
Description copied from interface:ImageInputStreamReads the next line of text from the input stream. It reads successive bytes, converting each byte separately into a character, until it encounters a line terminator or end of file; the characters read are then returned as aString. 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
nullis returned. Otherwise, each byte that is read is converted to typecharby 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, aStringis 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.
- Specified by:
readLinein interfaceDataInput- Specified by:
readLinein interfaceImageInputStream- Returns:
- a String containing a line of text from the stream.
- Throws:
IOException- if an I/O error occurs.
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readUTF
Description copied from interface:ImageInputStreamReads in a string that has been encoded using a modified UTF-8 format. The general contract ofreadUTFis that it reads a representation of a Unicode character string encoded in modified UTF-8 format; this string of characters is then returned as aString.First, two bytes are read and used to construct an unsigned 16-bit integer in the manner of the
readUnsignedShortmethod, 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(wherexmeans "may be0or1"), 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 byteaand a second byteb. If there is no byteb(because byteawas the last of the bytes to be read), or if bytebdoes not match the bit pattern10xxxxxx, then aUTFDataFormatExceptionis thrown. Otherwise, the group is converted to the character:
If the first byte of a group matches the bit pattern(char)(((a& 0x1F) << 6) | (b & 0x3F))1110xxxx, then the group consists of that byteaand two more bytesbandc. If there is no bytec(because byteawas one of the last two of the bytes to be read), or either bytebor bytecdoes not match the bit pattern10xxxxxx, then aUTFDataFormatExceptionis thrown. Otherwise, the group is converted to the character:
If the first byte of a group matches the pattern(char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F))1111xxxxor the pattern10xxxxxx, then aUTFDataFormatExceptionis thrown.If end of file is encountered at any time during this entire process, then a
java.io.EOFExceptionis 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.
- Specified by:
readUTFin interfaceDataInput- Specified by:
readUTFin interfaceImageInputStream- Returns:
- a String read from the stream.
- Throws:
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.
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readFully
Description copied from interface:ImageInputStreamReadslenbytes from the stream, and stores them intobstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFullyin interfaceDataInput- Specified by:
readFullyin interfaceImageInputStream- Parameters:
b- an array of bytes to be written to.off- the starting position withinbto write to.len- the maximum number ofbytes to read.- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Description copied from interface:ImageInputStreamReadsb.lengthbytes from the stream, and stores them intobstarting at index0. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFullyin interfaceDataInput- Specified by:
readFullyin interfaceImageInputStream- Parameters:
b- an array ofbytes.- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Description copied from interface:ImageInputStreamReadslenshorts (signed 16-bit integers) from the stream according to the current byte order, and stores them intosstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFullyin interfaceImageInputStream- Parameters:
s- an array of shorts to be written to.off- the starting position withinsto write to.len- the maximum number ofshorts to read.- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Description copied from interface:ImageInputStreamReadslenchars (unsigned 16-bit integers) from the stream according to the current byte order, and stores them intocstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFullyin interfaceImageInputStream- Parameters:
c- an array of chars to be written to.off- the starting position withincto write to.len- the maximum number ofchars to read.- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Description copied from interface:ImageInputStreamReadslenints (signed 32-bit integers) from the stream according to the current byte order, and stores them intoistarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFullyin interfaceImageInputStream- Parameters:
i- an array of ints to be written to.off- the starting position withinito write to.len- the maximum number ofints to read.- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Description copied from interface:ImageInputStreamReadslenlongs (signed 64-bit integers) from the stream according to the current byte order, and stores them intolstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFullyin interfaceImageInputStream- Parameters:
l- an array of longs to be written to.off- the starting position withinlto write to.len- the maximum number oflongs to read.- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Description copied from interface:ImageInputStreamReadslenfloats (32-bit IEEE single-precision floats) from the stream according to the current byte order, and stores them intofstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFullyin interfaceImageInputStream- Parameters:
f- an array of floats to be written to.off- the starting position withinfto write to.len- the maximum number offloats to read.- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Description copied from interface:ImageInputStreamReadslendoubles (64-bit IEEE double-precision floats) from the stream according to the current byte order, and stores them intodstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFullyin interfaceImageInputStream- Parameters:
d- an array of doubles to be written to.off- the starting position withindto write to.len- the maximum number ofdoubles to read.- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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getStreamPosition
Description copied from interface:ImageInputStreamReturns the current byte position of the stream. The next read will take place starting at this offset.- Specified by:
getStreamPositionin interfaceImageInputStream- Returns:
- a long containing the position of the stream.
- Throws:
IOException- if an I/O error occurs.
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getBitOffset
Description copied from interface:ImageInputStreamReturns the current bit offset, as an integer between 0 and 7, inclusive. The bit offset is updated implicitly by calls to thereadBitsmethod. 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 anyreadorreadFullymethod.- Specified by:
getBitOffsetin interfaceImageInputStream- Returns:
- an
intcontaining the bit offset between 0 and 7, inclusive. - Throws:
IOException- if an I/O error occurs.- See Also:
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setBitOffset
Description copied from interface:ImageInputStreamSets the bit offset to an integer between 0 and 7, inclusive. The byte offset within the stream, as returned bygetStreamPosition, 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.- Specified by:
setBitOffsetin interfaceImageInputStream- Parameters:
bitOffset- the desired offset, as anintbetween 0 and 7, inclusive.- Throws:
IOException- if an I/O error occurs.- See Also:
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readBit
Description copied from interface:ImageInputStreamReads a single bit from the stream and returns it as anintwith the value0or1. The bit offset is advanced by one and reduced modulo 8.- Specified by:
readBitin interfaceImageInputStream- Returns:
- an
intcontaining the value0or1. - Throws:
EOFException- if the stream reaches the end before reading all the bits.IOException- if an I/O error occurs.
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readBits
Description copied from interface:ImageInputStreamReads a bitstring from the stream and returns it as along, with the first bit read becoming the most significant bit of the output. The read starts within the byte indicated bygetStreamPosition, at the bit given bygetBitOffset. The bit offset is advanced bynumBitsand 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:
Note that the result oflong accum = 0L; for (int i = 0; i < numBits; i++) { accum <<= 1; // Shift left one bit to make room accum |= readBit(); }readBits(32)may thus not be equal to that ofreadInt()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.EOFExceptionis thrown.- Specified by:
readBitsin interfaceImageInputStream- Parameters:
numBits- the number of bits to read, as anintbetween 0 and 64, inclusive.- Returns:
- the bitstring, as a
longwith the last bit read stored in the least significant bit. - Throws:
EOFException- if the stream reaches the end before reading all the bits.IOException- if an I/O error occurs.
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length
public long length()Returns-1Lto indicate that the stream has unknown length. Subclasses must override this method to provide actual length information.- Specified by:
lengthin interfaceImageInputStream- Returns:
- -1L to indicate unknown length.
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skipBytes
Advances the current stream position by callingseek(getStreamPosition() + n).The bit offset is reset to zero.
- Specified by:
skipBytesin interfaceDataInput- Specified by:
skipBytesin interfaceImageInputStream- Parameters:
n- the number of bytes to seek forward.- Returns:
- an
intrepresenting the number of bytes skipped. - Throws:
IOException- ifgetStreamPositionthrows anIOExceptionwhen computing either the starting or ending position.
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skipBytes
Advances the current stream position by callingseek(getStreamPosition() + n).The bit offset is reset to zero.
- Specified by:
skipBytesin interfaceImageInputStream- Parameters:
n- the number of bytes to seek forward.- Returns:
- a
longrepresenting the number of bytes skipped. - Throws:
IOException- ifgetStreamPositionthrows anIOExceptionwhen computing either the starting or ending position.
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seek
Description copied from interface:ImageInputStreamSets the current stream position to the desired location. The next read will occur at this location. The bit offset is set to 0.An
IndexOutOfBoundsExceptionwill be thrown ifposis smaller than the flushed position (as returned bygetflushedPosition).It is legal to seek past the end of the file; a
java.io.EOFExceptionwill be thrown only if a read is performed.- Specified by:
seekin interfaceImageInputStream- Parameters:
pos- alongcontaining the desired file pointer position.- Throws:
IOException- if any other I/O error occurs.
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mark
public void mark()Pushes the current stream position onto a stack of marked positions.- Specified by:
markin interfaceImageInputStream
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reset
Resets the current stream byte and bit positions from the stack of marked positions.An
IOExceptionwill be thrown if the previous marked position lies in the discarded portion of the stream.- Specified by:
resetin interfaceImageInputStream- Throws:
IOException- if an I/O error occurs.
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flushBefore
Description copied from interface:ImageInputStreamDiscards the initial portion of the stream prior to the indicated position. Attempting to seek to an offset within the flushed portion of the stream will result in anIndexOutOfBoundsException.Calling
flushBeforemay 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.- Specified by:
flushBeforein interfaceImageInputStream- Parameters:
pos- alongcontaining the length of the stream prefix that may be flushed.- Throws:
IOException- if an I/O error occurs.
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flush
Description copied from interface:ImageInputStreamDiscards the initial position of the stream prior to the current stream position. Equivalent toflushBefore(getStreamPosition()).- Specified by:
flushin interfaceImageInputStream- Throws:
IOException- if an I/O error occurs.
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getFlushedPosition
public long getFlushedPosition()Description copied from interface:ImageInputStreamReturns the earliest position in the stream to which seeking may be performed. The returned value will be the maximum of all values passed into previous calls toflushBefore.- Specified by:
getFlushedPositionin interfaceImageInputStream- Returns:
- the earliest legal position for seeking, as a
long.
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isCached
public boolean isCached()Default implementation returns false. Subclasses should override this if they cache data.- Specified by:
isCachedin interfaceImageInputStream- Returns:
trueif thisImageInputStreamcaches data.- See Also:
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isCachedMemory
public boolean isCachedMemory()Default implementation returns false. Subclasses should override this if they cache data in main memory.- Specified by:
isCachedMemoryin interfaceImageInputStream- Returns:
trueif thisImageInputStreamcaches data in main memory.- See Also:
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isCachedFile
public boolean isCachedFile()Default implementation returns false. Subclasses should override this if they cache data in a temporary file.- Specified by:
isCachedFilein interfaceImageInputStream- Returns:
trueif thisImageInputStreamcaches data in a temporary file.- See Also:
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close
Description copied from interface:ImageInputStreamCloses the stream. Attempts to access a stream that has been closed may result inIOExceptions 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.- Specified by:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable- Specified by:
closein interfaceImageInputStream- Throws:
IOException- if an I/O error occurs.
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finalize
Deprecated, for removal: This API element is subject to removal in a future version.Finalization has been deprecated for removal. SeeObject.finalize()for background information and details about migration options.Finalizes this object prior to garbage collection. Theclosemethod is called to close any open input source. This method should not be called from application code.
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