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java.lang.Objectuk.ac.starlink.fits.AbstractArrayDataIO
uk.ac.starlink.fits.MappedFile
public class MappedFile
Provides mapped access to a data buffer using a single mapped byte buffer, compatible with nom.tam.util classes.
This class implements the nom.tam.util ArrayDataInput, ArrayDataOutput and RandomAccess interfaces in the same way that nom.tam.util.BufferedFile does. Hence it can be used as a drop-in replacement for BufferedFile. Unlike BufferedFile however, it does mapped access to files (using java.nio.Buffer objects). This may be moderately more efficient for sequential access to a file, but is dramatically more efficient if very random access is required. This is because BufferedFile effectively always assumes that you are going to read sequentially, so that accessing a single datum distant from (or before) the last datum accessed always results in filling a whole buffer.
Nested Class Summary | |
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static class |
MappedFile.FileTooLongException
Exception indicating that a file is too long to map. |
Constructor Summary | |
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MappedFile(ByteBuffer buf)
Constructs a MappedFile object from a byte buffer. |
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MappedFile(String filename)
Constructs a MappedFile object by mapping the whole of an existing file using read-only mode. |
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MappedFile(String filename,
String mode)
Constructs a MappedFile object by mapping the whole of an existing file with a given mode. |
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MappedFile(String filename,
String mode,
long start,
int size)
Constructs a MappedFile object by mapping part of an existing file with a given mode. |
Method Summary | |
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void |
close()
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CopyableRandomAccess |
copyAccess()
Returns a new copy of this object. |
void |
flush()
|
protected byte |
get()
Reads one byte from the current position. |
protected void |
get(byte[] buf,
int offset,
int length)
Reads bytes into a buffer from the current position. |
long |
getFilePointer()
|
long |
length()
Returns the size of this buffer. |
protected void |
put(byte b)
Writes a single byte at the current position. |
protected void |
put(byte[] buf,
int offset,
int length)
Writes bytes from a buffer to the current position. |
protected long |
remaining()
Returns the number of bytes remaining between the current position and the end of the file. |
void |
seek(long offsetFromStart)
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long |
skip(long offset)
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int |
skipBytes(int toSkip)
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Methods inherited from class uk.ac.starlink.fits.AbstractArrayDataIO |
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read, read, read, read, read, read, read, read, read, read, read, read, read, read, read, read, readArray, readBoolean, readByte, readChar, readDouble, readFloat, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedShort, readUTF, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, writeArray, writeBoolean, writeByte, writeBytes, writeChar, writeChars, writeDouble, writeFloat, writeInt, writeLong, writeShort, writeUTF |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface nom.tam.util.ArrayDataInput |
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read, read, read, read, read, read, read, read, read, read, read, read, read, read, read, read, readArray |
Methods inherited from interface java.io.DataInput |
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readBoolean, readByte, readChar, readDouble, readFloat, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedShort, readUTF |
Constructor Detail |
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public MappedFile(ByteBuffer buf)
buf
- byte bufferpublic MappedFile(String filename) throws IOException
filename
- name of the file to map
MappedFile.FileTooLongException
- if the file is too long to map
IOException
public MappedFile(String filename, String mode) throws IOException
filename
- name of the file to mapmode
- mode
MappedFile.FileTooLongException
- if the file is too long to map
IOException
public MappedFile(String filename, String mode, long start, int size) throws IOException
filename
- name of the file to mapmode
- modestart
- offset of region to mapsize
- length of region to map
IOException
Method Detail |
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public void seek(long offsetFromStart) throws IOException
seek
in interface nom.tam.util.RandomAccess
IOException
public long skip(long offset)
skip
in interface nom.tam.util.ArrayDataInput
public long getFilePointer()
getFilePointer
in interface nom.tam.util.RandomAccess
public CopyableRandomAccess copyAccess() throws IOException
CopyableRandomAccess
copyAccess
in interface CopyableRandomAccess
IOException
public int skipBytes(int toSkip)
skipBytes
in interface DataInput
protected byte get() throws IOException
AbstractArrayDataIO
get
in class AbstractArrayDataIO
IOException
protected void get(byte[] buf, int offset, int length) throws IOException
AbstractArrayDataIO
get
in class AbstractArrayDataIO
buf
- destination bufferoffset
- offset of first byte in buf
to be writtenlength
- maximum number of bytes to be written to
buf
IOException
protected void put(byte b) throws IOException
AbstractArrayDataIO
put
in class AbstractArrayDataIO
b
- output byte
IOException
protected void put(byte[] buf, int offset, int length) throws IOException
AbstractArrayDataIO
put
in class AbstractArrayDataIO
buf
- source bufferoffset
- offset of first byte in buf
to be readlength
- number of bytes from buf
to be read
IOException
public long length()
AbstractArrayDataIO
length
in class AbstractArrayDataIO
protected long remaining()
AbstractArrayDataIO
Long.MAX_VALUE
;
remaining
in class AbstractArrayDataIO
public void close()
close
in interface nom.tam.util.ArrayDataInput
close
in interface nom.tam.util.ArrayDataOutput
public void flush()
flush
in interface nom.tam.util.ArrayDataOutput
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Copyright © 2004 CLRC: Central Laboratory of the Research Councils. All rights reserved. | ||||||||
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