public interface ImageInputStream extends DataInput, Closeable
A seekable input stream interface for use by ImageReaders. Various input sources, such as InputStreams and Files, 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.
ImageInputStreamImpl, FileImageInputStream, FileCacheImageInputStream, MemoryCacheImageInputStream
void setByteOrder(ByteOrder byteOrder)
Sets 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.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(), readBits(int)
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.
ByteOrder.BIG_ENDIAN or ByteOrder.LITTLE_ENDIAN, indicating which byte order is being used.ByteOrder, setByteOrder(java.nio.ByteOrder)
int read() throws IOException
Reads a single byte from the stream and returns it as an integer between 0 and 255. If the end of the stream is reached, -1 is returned.
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
Reads up to 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 Reads up to 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 bytes 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 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. 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 bytes to read.IndexOutOfBoundsException - if len is negative.NullPointerException - if buf is null.IOException - if an I/O error occurs.boolean readBoolean()
throws IOException Reads a byte from the stream and returns a 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 Reads a byte from the stream and returns it as a 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 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.
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 bytevalues, 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 Reads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, and returns the result as a 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.getByteOrder()int readUnsignedShort()
throws IOException 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.
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.getByteOrder()char readChar()
throws IOException Equivalent to 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.readUnsignedShort()int readInt()
throws IOException Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as an 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.getByteOrder()long readUnsignedInt()
throws IOException 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.
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.getByteOrder()long readLong()
throws IOException Reads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as a 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.getByteOrder()float readFloat()
throws IOException Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as a 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.getByteOrder()double readDouble()
throws IOException Reads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as a 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.getByteOrder()String readLine()
throws IOException Reads 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 a 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 Reads in a string that has been encoded using a modified UTF-8 format. The general contract of 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 an 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 Reads len bytes from the stream, and stores them into b starting at index off. If the end of the stream is reached, an 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 bytes 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 Reads b.length bytes from the stream, and stores them into b starting at index 0. If the end of the stream is reached, an 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.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 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. If the end of the stream is reached, an 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 shorts 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 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. If the end of the stream is reached, an 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 chars 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 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. If the end of the stream is reached, an 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 ints 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 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. If the end of the stream is reached, an 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 longs 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 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. If the end of the stream is reached, an 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 floats 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 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. If the end of the stream is reached, an 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 doubles 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 Returns the current byte position of the stream. The next read will take place starting at this offset.
IOException - if an I/O error occurs.int getBitOffset()
throws IOException Returns the current bit offset, as an integer between 0 and 7, inclusive. The bit offset is updated implicitly by calls to the 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.setBitOffset(int)void setBitOffset(int bitOffset)
throws IOException Sets the bit offset to an integer between 0 and 7, inclusive. The byte offset within the stream, as returned by 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.getBitOffset()int readBit()
throws IOException Reads a single bit from the stream and returns it as an 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 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. 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, an 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 Returns the total length of the stream, if known. Otherwise, -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 Moves the stream position forward by a given number of bytes. It is possible that this method will only be able to skip forward by a smaller number of bytes than requested, for example if the end of the stream is reached. In all cases, the actual number of bytes skipped is returned. The bit offset is set to zero prior to advancing the position.
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 Moves the stream position forward by a given number of bytes. This method is identical to 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
Sets the current stream position to the desired location. The next read will occur at this location. The bit offset is set to 0.
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; an 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()
Marks a position in the stream to be returned to by a subsequent call to reset. Unlike a standard InputStream, all ImageInputStreams 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 Returns the stream pointer to its previous position, including the bit offset, at the time of the most recent unmatched call to 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 Discards 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 an 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 Discards the initial position of the stream prior to the current stream position. Equivalent to flushBefore(getStreamPosition()).
IOException - if an I/O error occurs.long getFlushedPosition()
Returns 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 to flushBefore.
long.boolean isCached()
Returns 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.isCachedMemory(), isCachedFile()
boolean isCachedMemory()
Returns 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.isCached(), isCachedFile()
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. 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.isCached(), isCachedMemory()
void close()
throws IOException Closes the stream. Attempts to access a stream that has been closed may result in IOExceptions 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.
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