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java.lang.Object | +--gov.nist.nlpir.misc.io.BufferedRandomAccessFile
A buffered version of RandomAccessFile.
Instances of this class realise substantial speed increases over
RandomAccessFile through the use of buffering. This is a subclass of
Object, as it was not possible to subclass RandomAccessFile because
many of the methods are final. However, if it is necessary to use
BufferedRandomAccessFile and RandomAccessFile interchangeably, both
classes implement the DataInput and DataOutput interfaces.
By Alex McManus, based on Sun's source code for RandomAccessFile.
Copyright 1997 Centre For Intelligent Systems,
Univeristy of Wales, Aberystwyth.
Modified by National Institute of Standards and Technology for use
in the Information Retrieval Framework (IRF):
DataInput
,
DataOutput
,
RandomAccessFile
Field Summary | |
protected byte[] |
buffer
The buffer used to load the data. |
(package private) boolean |
bufferModified
True if the data in the buffer has been modified. |
protected long |
bufferStart
The offset in bytes of the start of the buffer, from the start of the file. |
static int |
CREATE
Create the file rather than overwriting it. |
protected long |
dataEnd
The offset in bytes of the end of the data in the buffer, from the start of the file. |
protected int |
dataSize
The size of the data stored in the buffer, in bytes. |
protected static int |
defaultBufferSize
The default buffer size, in bytes. |
protected boolean |
endOfFile
True if we are at the end of the file. |
protected java.io.RandomAccessFile |
file
The underlying RandomAccessFile. |
protected long |
filePosition
The offset in bytes from the file start, of the next read or write operation. |
protected int |
mode
The access mode of the file. |
static int |
READ
Read from the file. |
static int |
WRITE
Write to the file. |
Constructor Summary | |
BufferedRandomAccessFile(java.lang.String filename,
int mode)
Create a new buffered random-access file with a default buffer size. |
|
BufferedRandomAccessFile(java.lang.String filename,
int mode,
int bufferSize)
Create a new buffered random-access file with a specified buffer size. |
Method Summary | |
static void |
benchmark(java.lang.String filename,
int bufferSize)
Benchmark the performance of the new BufferedRandomAccessFile class. |
void |
close()
Close the file, and release any associated system resources. |
void |
flush()
Copy the contents of the buffer to the disk. |
long |
getFilePointer()
Returns the current position in the file, where the next read or write will occur. |
long |
getLength()
Get the length of the file. |
static void |
main(java.lang.String[] argv)
Test the BufferedRandomAccessFile class. |
int |
read()
Read a byte of data from the file, blocking until data is available. |
int |
read(byte[] b)
Read up to b.length( ) bytes into an array. |
int |
read(byte[] b,
int off,
int len)
Read up to len bytes into an array, at a specified
offset. |
boolean |
readBoolean()
Reads a boolean from this file. |
byte |
readByte()
Reads a signed 8-bit value from this file. |
private int |
readBytes(byte[] b,
int off,
int len)
Read up to len bytes into an array, at a specified
offset. |
char |
readChar()
Reads a Unicode character from this file. |
double |
readDouble()
Reads a double from this file. |
float |
readFloat()
Reads a float from this file. |
void |
readFully(byte[] b)
Reads b.length bytes from this file into the byte
array. |
void |
readFully(byte[] b,
int off,
int len)
Reads exactly len bytes from this file into the byte
array. |
int |
readInt()
Reads a signed 32-bit integer from this file. |
java.lang.String |
readLine()
Reads the next line of text from this file. |
long |
readLong()
Reads a signed 64-bit integer from this file. |
short |
readShort()
Reads a signed 16-bit number from this file. |
int |
readUnsignedByte()
Reads an unsigned 8-bit number from this file. |
int |
readUnsignedShort()
Reads an unsigned 16-bit number from this file. |
java.lang.String |
readUTF()
Reads in a string from this file. |
void |
seek(long pos)
Set the position in the file for the next read or write. |
int |
skipBytes(int n)
Skips exactly n bytes of input. |
static void |
testBlocks(java.lang.String filename)
Test the block operations of the BufferedRandomAccessFile class. |
static void |
testBytes(java.lang.String filename,
int bufferSize)
Test the byte operations of the BufferedRandomAccessFile class. |
java.lang.String |
toString()
Create a string representation of this object. |
void |
unread()
Unread the last byte read. |
void |
write(byte[] b)
Writes b.length bytes from the specified byte array
starting at offset off to this file. |
void |
write(byte[] b,
int off,
int len)
Writes len bytes from the specified byte array
starting at offset off to this file. |
void |
write(int b)
Write a byte to the file. |
void |
writeBoolean(boolean v)
Writes a boolean to the file as a 1-byte value. |
void |
writeByte(int v)
Writes a byte to the file as a 1-byte value. |
void |
writeBytes(byte[] b,
int off,
int len)
Write len bytes from an array to the file. |
void |
writeBytes(char[] b,
int off,
int len)
Writes the character array to the file as a sequence of bytes. |
void |
writeBytes(java.lang.String s)
Writes the string to the file as a sequence of bytes. |
void |
writeChar(int v)
Writes a char to the file as a 2-byte value, high
byte first. |
void |
writeChars(java.lang.String s)
Writes a string to the file as a sequence of characters. |
void |
writeDouble(double v)
Converts the double argument to a long using the
doubleToLongBits method in class Double ,
and then writes that long value to the file as an
8-byte quantity, high byte first. |
void |
writeFloat(float v)
Converts the float argument to an int using the
floatToIntBits method in class Float ,
and then writes that int value to the file as a
4-byte quantity, high byte first. |
void |
writeInt(int v)
Writes an int to the file as four bytes, high byte first. |
void |
writeLong(long v)
Writes a long to the file as eight bytes, high byte first. |
void |
writeShort(int v)
Writes a short to the file as two bytes, high byte first. |
void |
writeUTF(java.lang.String str)
Writes a string to the file using UTF-8 encoding in a machine-independent manner. |
Methods inherited from class java.lang.Object |
|
Field Detail |
public static final int READ
public static final int WRITE
public static final int CREATE
protected static final int defaultBufferSize
protected java.io.RandomAccessFile file
protected long filePosition
protected byte[] buffer
protected long bufferStart
protected long dataEnd
bufferStart + dataSize
, but it is cached to speed
up the read( ) method.protected int dataSize
protected boolean endOfFile
protected int mode
boolean bufferModified
Constructor Detail |
public BufferedRandomAccessFile(java.lang.String filename, int mode) throws java.io.IOException
filename
- the name of the file.mode
- how the file is to be opened. This may be a
combination (logical OR) of CREATE, WRITE, and READ.public BufferedRandomAccessFile(java.lang.String filename, int mode, int bufferSize) throws java.io.IOException
filename
- the name of the file.mode
- how the file is to be opened. This may be a
combination (logical OR) of CREATE, WRITE, and READ.bufferSize
- the size of the temporary buffer, in bytes.Method Detail |
public void close() throws java.io.IOException
public final void seek(long pos) throws java.io.IOException
pos
- the offset (in bytes) from the start of the file.public final long getFilePointer() throws java.io.IOException
public long getLength() throws java.io.IOException
public void flush() throws java.io.IOException
public final int read() throws java.io.IOException
private int readBytes(byte[] b, int off, int len) throws java.io.IOException
len
bytes into an array, at a specified
offset. This will block until at least one byte has been read.b
- the byte array to receive the bytes.off
- the offset in the array where copying will start.len
- the number of bytes to copy.public int read(byte[] b, int off, int len) throws java.io.IOException
len
bytes into an array, at a specified
offset. This will block until at least one byte has been read.b
- the byte array to receive the bytes.off
- the offset in the array where copying will start.len
- the number of bytes to copy.public int read(byte[] b) throws java.io.IOException
b.length( )
bytes into an array. This
will block until at least one byte has been read.b
- the byte array to receive the bytes.public final void readFully(byte[] b) throws java.io.IOException
b.length
bytes from this file into the byte
array. This method reads repeatedly from the file until all the
bytes are read. This method blocks until all the bytes are read,
the end of the stream is detected, or an exception is thrown.b
- the buffer into which the data is read.public final void readFully(byte[] b, int off, int len) throws java.io.IOException
len
bytes from this file into the byte
array. This method reads repeatedly from the file until all the
bytes are read. This method blocks until all the bytes are read,
the end of the stream is detected, or an exception is thrown.b
- the buffer into which the data is read.off
- the start offset of the data.len
- the number of bytes to read.public int skipBytes(int n) throws java.io.IOException
n
bytes of input.
This method blocks until all the bytes are skipped, the end of
the stream is detected, or an exception is thrown.n
- the number of bytes to be skipped.n
.public final void unread()
public final void write(int b) throws java.io.IOException
Caveat: the effects of seek( )ing beyond the end of the file are undefined.
public final void writeBytes(byte[] b, int off, int len) throws java.io.IOException
len
bytes from an array to the file.b
- the array containing the data.off
- the offset in the array to the data.len
- the length of the data.public void write(byte[] b) throws java.io.IOException
b.length
bytes from the specified byte array
starting at offset off
to this file.b
- the data.public void write(byte[] b, int off, int len) throws java.io.IOException
len
bytes from the specified byte array
starting at offset off
to this file.b
- the data.off
- the start offset in the data.len
- the number of bytes to write.public final boolean readBoolean() throws java.io.IOException
boolean
from this file. This method reads a
single byte from the file. A value of 0
represents
false
. Any other value represents true
.
This method blocks until the byte is read, the end of the stream
is detected, or an exception is thrown.boolean
value read.public final byte readByte() throws java.io.IOException
b
, where
0 <= b <= 255
,
then the result is:
(byte)(b)
This method blocks until the byte is read, the end of the stream is detected, or an exception is thrown.
byte
.public final int readUnsignedByte() throws java.io.IOException
This method blocks until the byte is read, the end of the stream is detected, or an exception is thrown.
public final short readShort() throws java.io.IOException
b1
and b2
, where each of the two values is
between 0
and 255
, inclusive, then the
result is equal to:
(short)((b1 << 8) | b2)
This method blocks until the two bytes are read, the end of the stream is detected, or an exception is thrown.
public final int readUnsignedShort() throws java.io.IOException
b1
and b2
, where
0 <= b1, b2 <= 255
,
then the result is equal to:
(b1 << 8) | b2
This method blocks until the two bytes are read, the end of the stream is detected, or an exception is thrown.
public final char readChar() throws java.io.IOException
b1
and b2
, where
0 <= b1, b2 <= 255
,
then the result is equal to:
(char)((b1 << 8) | b2)
This method blocks until the two bytes are read, the end of the stream is detected, or an exception is thrown.
public final int readInt() throws java.io.IOException
b1
,
b2
, b3
, and b4
, where
0 <= b1, b2, b3, b4 <= 255
,
then the result is equal to:
(b1 << 24) | (b2 << 16) + (b3 << 8) + b4
This method blocks until the four bytes are read, the end of the stream is detected, or an exception is thrown.
int
.public final long readLong() throws java.io.IOException
b1
, b2
, b3
,
b4
, b5
, b6
,
b7
, and b8,
where:
0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
then the result is equal to:
((long)b1 << 56) + ((long)b2 << 48) + ((long)b3 << 40) + ((long)b4 << 32) + ((long)b5 << 24) + ((long)b6 << 16) + ((long)b7 << 8) + b8
This method blocks until the eight bytes are read, the end of the stream is detected, or an exception is thrown.
long
.public final float readFloat() throws java.io.IOException
float
from this file. This method reads an
int
value as if by the readInt
method
and then converts that int
to a float
using the intBitsToFloat
method in class
Float
.
This method blocks until the four bytes are read, the end of the stream is detected, or an exception is thrown.
float
.RandomAccessFile.readInt()
,
Float.intBitsToFloat(int)
public final double readDouble() throws java.io.IOException
double
from this file. This method reads a
long
value as if by the readLong
method
and then converts that long
to a double
using the longBitsToDouble
method in
class Double
.
This method blocks until the eight bytes are read, the end of the stream is detected, or an exception is thrown.
double
.RandomAccessFile.readLong()
,
Double.longBitsToDouble(long)
public final java.lang.String readLine() throws java.io.IOException
A line of text is terminated by a carriage-return character
('\r'
), a newline character ('\n'
), a
carriage-return character immediately followed by a newline
character, or the end of the input stream. The line-terminating
character(s), if any, are included as part of the string returned.
This method blocks until a newline character is read, a carriage return and the byte following it are read (to see if it is a newline), the end of the stream is detected, or an exception is thrown.
public final java.lang.String readUTF() throws java.io.IOException
The first two bytes are read as if by
readUnsignedShort
. This value gives the number of
following bytes that are in the encoded string, not
the length of the resulting string. The following bytes are then
interpreted as bytes encoding characters in the UTF-8 format
and are converted into characters.
This method blocks until all the bytes are read, the end of the stream is detected, or an exception is thrown.
RandomAccessFile.readUnsignedShort()
public final void writeBoolean(boolean v) throws java.io.IOException
boolean
to the file as a 1-byte value. The
value true
is written out as the value
(byte)1
; the value false
is written out
as the value (byte)0
.v
- a boolean
value to be written.public final void writeByte(int v) throws java.io.IOException
byte
to the file as a 1-byte value.v
- a byte
value to be written.public final void writeShort(int v) throws java.io.IOException
short
to the file as two bytes, high byte first.v
- a short
to be written.public final void writeChar(int v) throws java.io.IOException
char
to the file as a 2-byte value, high
byte first.v
- a char
value to be written.public final void writeInt(int v) throws java.io.IOException
int
to the file as four bytes, high byte first.v
- an int
to be written.public final void writeLong(long v) throws java.io.IOException
long
to the file as eight bytes, high byte first.v
- a long
to be written.public final void writeFloat(float v) throws java.io.IOException
int
using the
floatToIntBits
method in class Float
,
and then writes that int
value to the file as a
4-byte quantity, high byte first.v
- a float
value to be written.Float.floatToIntBits(float)
public final void writeDouble(double v) throws java.io.IOException
long
using the
doubleToLongBits
method in class Double
,
and then writes that long
value to the file as an
8-byte quantity, high byte first.v
- a double
value to be written.Double.doubleToLongBits(double)
public final void writeBytes(java.lang.String s) throws java.io.IOException
s
- a string of bytes to be written.public final void writeBytes(char[] b, int off, int len) throws java.io.IOException
b
- a character array of bytes to be written.off
- the index of the first character to write.len
- the number of characters to write.public final void writeChars(java.lang.String s) throws java.io.IOException
writeChar
method.s
- a String
value to be written.RandomAccessFile.writeChar(int)
public final void writeUTF(java.lang.String str) throws java.io.IOException
First, two bytes are written to the file as if by the
writeShort
method giving the number of bytes to
follow. This value is the number of bytes actually written out,
not the length of the string. Following the length, each character
of the string is output, in sequence, using the UTF-8 encoding
for each character.
str
- a string to be written.public java.lang.String toString()
public static void testBytes(java.lang.String filename, int bufferSize)
filename
- the name of the test file to generate.bufferSize
- the size of the buffer to use.public static void testBlocks(java.lang.String filename)
filename
- the name of the test file to generate.public static void benchmark(java.lang.String filename, int bufferSize)
filename
- the name of the test file.bufferSize
- the buffer size to use.public static void main(java.lang.String[] argv)
argv
- Usage: testBytes(java.lang.String, int)
,
testBlocks(java.lang.String)
,
benchmark(java.lang.String, int)
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