Class XRandomAccessFile
- java.lang.Object
-
- com.sun.xfile.XRandomAccessFile
-
- All Implemented Interfaces:
java.io.DataInput
,java.io.DataOutput
public class XRandomAccessFile extends java.lang.Object implements java.io.DataOutput, java.io.DataInput
Instances of this class support both reading and writing to a random access file. An application can modify the position in the file at which the next read or write occurs. This class provides a sense of security by offering methods that allow specified mode accesses of read-only or read-write to files.
-
-
Constructor Summary
Constructors Constructor Description XRandomAccessFile(XFile xf, java.lang.String mode)
Creates a random access file stream to read from, and optionally to write to, the file specified by theXFile
argument.XRandomAccessFile(java.lang.String name, java.lang.String mode)
Creates a random access file to read from, and optionally to write to, a file with the specified name.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
close()
Closes this random access file and flushes any unwritten data to the file.void
flush()
Forces any buffered output bytes to be written out.long
getFilePointer()
Returns the current offset in this file.long
length()
Returns the length of this file.int
read()
Reads a byte of data from this file.int
read(byte[] b)
Reads up tob.length
bytes of data from this file into an array of bytes.int
read(byte[] b, int off, int len)
Reads up tolen
bytes of data from this file into an array of bytes.boolean
readBoolean()
Reads aboolean
from this file.byte
readByte()
Reads a signed 8-bit value from this file.char
readChar()
Reads a Unicode character from this file.double
readDouble()
Reads adouble
from this file.float
readFloat()
Reads afloat
from this file.void
readFully(byte[] b)
Readsb.length
bytes from this file into the byte array.void
readFully(byte[] b, int off, int len)
Reads exactlylen
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)
Sets the offset from the beginning of this file at which the next read or write occurs.int
skipBytes(int n)
Skips exactlyn
bytes of input.void
write(byte[] b)
Writesb.length
bytes from the specified byte array starting at offsetoff
to this file.void
write(byte[] b, int off, int len)
Writeslen
bytes from the specified byte array starting at offsetoff
to this file.void
write(int b)
Writes the specified byte to this file.void
writeBoolean(boolean v)
Writes aboolean
to the file as a 1-byte value.void
writeByte(int v)
Writes abyte
to the file as a 1-byte value.void
writeBytes(java.lang.String s)
Writes the string to the file as a sequence of bytes.void
writeChar(int v)
Writes achar
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 along
using thedoubleToLongBits
method in classDouble
, and then writes thatlong
value to the file as an 8-byte quantity, high byte first.void
writeFloat(float v)
Converts the float argument to anint
using thefloatToIntBits
method in classFloat
, and then writes thatint
value to the file as a 4-byte quantity, high byte first.void
writeInt(int v)
Writes anint
to the file as four bytes, high byte first.void
writeLong(long v)
Writes along
to the file as eight bytes, high byte first.void
writeShort(int v)
Writes ashort
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.
-
-
-
Constructor Detail
-
XRandomAccessFile
public XRandomAccessFile(XFile xf, java.lang.String mode) throws java.io.IOException
Creates a random access file stream to read from, and optionally to write to, the file specified by theXFile
argument. The mode argument must either be equal to"r"
or to"rw"
, indicating either to open the file for input, or for both input and output, respectively.- Parameters:
xf
- the XFile object.mode
- the access mode.- Throws:
java.lang.IllegalArgumentException
- if the mode argument is not equal to"r"
or to"rw"
.java.io.IOException
- if an I/O error occurs.
-
XRandomAccessFile
public XRandomAccessFile(java.lang.String name, java.lang.String mode) throws java.io.IOException
Creates a random access file to read from, and optionally to write to, a file with the specified name.The mode argument must either be equal to
"r"
or"rw"
, indicating either to open the file for input or for both input and output.- Parameters:
name
- the native or URL file name.mode
- the access mode.- Throws:
java.lang.IllegalArgumentException
- if the mode argument is not equal to"r"
or to"rw"
.java.io.IOException
- if an I/O error occurs.
-
-
Method Detail
-
read
public int read() throws java.io.IOException
Reads a byte of data from this file.- Returns:
- the next byte of data, or
-1
if the end of the file is reached. - Throws:
java.io.IOException
- if an I/O error occurs.
-
read
public int read(byte[] b, int off, int len) throws java.io.IOException
Reads up tolen
bytes of data from this file into an array of bytes.- Parameters:
b
- the buffer into which the data is read.off
- the start offset of the data.len
- the maximum number of bytes read.- Returns:
- the total number of bytes read into the buffer, or
-1
if there is no more data because the end of the file has been reached. - Throws:
java.io.IOException
- if an I/O error occurs.
-
read
public int read(byte[] b) throws java.io.IOException
Reads up tob.length
bytes of data from this file into an array of bytes.- Parameters:
b
- the buffer into which the data is read.- Returns:
- the total number of bytes read into the buffer, or
-1
if there is no more data because the end of this file has been reached. - Throws:
java.io.IOException
- if an I/O error occurs.
-
readFully
public final void readFully(byte[] b) throws java.io.IOException
Readsb.length
bytes from this file into the byte array.- Specified by:
readFully
in interfacejava.io.DataInput
- Parameters:
b
- the buffer into which the data is read.- Throws:
java.io.EOFException
- if this file reaches the end before reading all the bytes.java.io.IOException
- if an I/O error occurs.
-
readFully
public final void readFully(byte[] b, int off, int len) throws java.io.IOException
Reads exactlylen
bytes from this file into the byte array.- Specified by:
readFully
in interfacejava.io.DataInput
- Parameters:
b
- the buffer into which the data is read.off
- the start offset of the data.len
- the number of bytes to read.- Throws:
java.io.EOFException
- if this file reaches the end before reading all the bytes.java.io.IOException
- if an I/O error occurs.
-
skipBytes
public int skipBytes(int n) throws java.io.IOException
Skips exactlyn
bytes of input.- Specified by:
skipBytes
in interfacejava.io.DataInput
- Parameters:
n
- the number of bytes to be skipped.- Returns:
- the number of bytes skipped, which is always
n
. - Throws:
java.io.EOFException
- if this file reaches the end before skipping all the bytes.java.io.IOException
- if an I/O error occurs.
-
write
public void write(int b) throws java.io.IOException
Writes the specified byte to this file.- Specified by:
write
in interfacejava.io.DataOutput
- Parameters:
b
- thebyte
to be written.- Throws:
java.io.IOException
- if an I/O error occurs.
-
write
public void write(byte[] b) throws java.io.IOException
Writesb.length
bytes from the specified byte array starting at offsetoff
to this file.- Specified by:
write
in interfacejava.io.DataOutput
- Parameters:
b
- the data.- Throws:
java.io.IOException
- if an I/O error occurs.
-
write
public void write(byte[] b, int off, int len) throws java.io.IOException
Writeslen
bytes from the specified byte array starting at offsetoff
to this file.- Specified by:
write
in interfacejava.io.DataOutput
- Parameters:
b
- the data.off
- the start offset in the data.len
- the number of bytes to write.- Throws:
java.io.IOException
- if an I/O error occurs.
-
getFilePointer
public long getFilePointer() throws java.io.IOException
Returns the current offset in this file.- Returns:
- the offset from the beginning of the file, in bytes, at which the next read or write occurs.
- Throws:
java.io.IOException
- if an I/O error occurs.
-
seek
public void seek(long pos) throws java.io.IOException
Sets the offset from the beginning of this file at which the next read or write occurs.- Parameters:
pos
- the absolute position.- Throws:
java.io.IOException
- if an I/O error occurs.
-
length
public long length() throws java.io.IOException
Returns the length of this file.- Returns:
- the length of this file.
- Throws:
java.io.IOException
- if an I/O error occurs.
-
flush
public void flush() throws java.io.IOException
Forces any buffered output bytes to be written out.- Throws:
java.io.IOException
- if an I/O error occurs.
-
close
public void close() throws java.io.IOException
Closes this random access file and flushes any unwritten data to the file. After the file is closed further I/O operations may throw IOException.- Throws:
java.io.IOException
- if an I/O error occurs.
-
readBoolean
public final boolean readBoolean() throws java.io.IOException
Reads aboolean
from this file. This method reads a single byte from the file. A value of0
representsfalse
. Any other value representstrue
. This method blocks until the byte is read, the end of the stream is detected, or an exception is thrown.- Specified by:
readBoolean
in interfacejava.io.DataInput
- Returns:
- the
boolean
value read. - Throws:
java.io.EOFException
- if this file has reached the end.java.io.IOException
- if an I/O error occurs.
-
readByte
public final byte readByte() throws java.io.IOException
Reads a signed 8-bit value from this file. This method reads a byte from the file. If the byte read isb
, where0 <= 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.
- Specified by:
readByte
in interfacejava.io.DataInput
- Returns:
- the next byte of this file as a signed 8-bit
byte
. - Throws:
java.io.EOFException
- if this file has reached the end.java.io.IOException
- if an I/O error occurs.
-
readUnsignedByte
public final int readUnsignedByte() throws java.io.IOException
Reads an unsigned 8-bit number from this file. This method reads a byte from this file and returns that byte.This method blocks until the byte is read, the end of the stream is detected, or an exception is thrown.
- Specified by:
readUnsignedByte
in interfacejava.io.DataInput
- Returns:
- the next byte of this file, interpreted as an unsigned 8-bit number.
- Throws:
java.io.EOFException
- if this file has reached the end.java.io.IOException
- if an I/O error occurs.
-
readShort
public final short readShort() throws java.io.IOException
Reads a signed 16-bit number from this file. The method reads 2 bytes from this file. If the two bytes read, in order, areb1
andb2
, where each of the two values is between0
and255
, 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.
- Specified by:
readShort
in interfacejava.io.DataInput
- Returns:
- the next two bytes of this file, interpreted as a signed 16-bit number.
- Throws:
java.io.EOFException
- if this file reaches the end before reading two bytes.java.io.IOException
- if an I/O error occurs.
-
readUnsignedShort
public final int readUnsignedShort() throws java.io.IOException
Reads an unsigned 16-bit number from this file. This method reads two bytes from the file. If the bytes read, in order, areb1
andb2
, where0 <= 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.
- Specified by:
readUnsignedShort
in interfacejava.io.DataInput
- Returns:
- the next two bytes of this file, interpreted as an unsigned 16-bit integer.
- Throws:
java.io.EOFException
- if this file reaches the end before reading two bytes.java.io.IOException
- if an I/O error occurs.
-
readChar
public final char readChar() throws java.io.IOException
Reads a Unicode character from this file. This method reads two bytes from the file. If the bytes read, in order, areb1
andb2
, where0 <= 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.
- Specified by:
readChar
in interfacejava.io.DataInput
- Returns:
- the next two bytes of this file as a Unicode character.
- Throws:
java.io.EOFException
- if this file reaches the end before reading two bytes.java.io.IOException
- if an I/O error occurs.
-
readInt
public final int readInt() throws java.io.IOException
Reads a signed 32-bit integer from this file. This method reads 4 bytes from the file. If the bytes read, in order, areb1
,b2
,b3
, andb4
, where0 <= 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.
- Specified by:
readInt
in interfacejava.io.DataInput
- Returns:
- the next four bytes of this file, interpreted as an
int
. - Throws:
java.io.EOFException
- if this file reaches the end before reading four bytes.java.io.IOException
- if an I/O error occurs.
-
readLong
public final long readLong() throws java.io.IOException
Reads a signed 64-bit integer from this file. This method reads eight bytes from the file. If the bytes read, in order, areb1
,b2
,b3
,b4
,b5
,b6
,b7
, andb8,
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.
- Specified by:
readLong
in interfacejava.io.DataInput
- Returns:
- the next eight bytes of this file, interpreted as a
long
. - Throws:
java.io.EOFException
- if this file reaches the end before reading eight bytes.java.io.IOException
- if an I/O error occurs.
-
readFloat
public final float readFloat() throws java.io.IOException
Reads afloat
from this file. This method reads anint
value as if by thereadInt
method and then converts thatint
to afloat
using theintBitsToFloat
method in classFloat
.This method blocks until the four bytes are read, the end of the stream is detected, or an exception is thrown.
- Specified by:
readFloat
in interfacejava.io.DataInput
- Returns:
- the next four bytes of this file, interpreted as a
float
. - Throws:
java.io.EOFException
- if this file reaches the end before reading four bytes.java.io.IOException
- if an I/O error occurs.- See Also:
readInt()
,Float.intBitsToFloat(int)
-
readDouble
public final double readDouble() throws java.io.IOException
Reads adouble
from this file. This method reads along
value as if by thereadLong
method and then converts thatlong
to adouble
using thelongBitsToDouble
method in classDouble
.This method blocks until the eight bytes are read, the end of the stream is detected, or an exception is thrown.
- Specified by:
readDouble
in interfacejava.io.DataInput
- Returns:
- the next eight bytes of this file, interpreted as a
double
. - Throws:
java.io.EOFException
- if this file reaches the end before reading eight bytes.java.io.IOException
- if an I/O error occurs.- See Also:
readLong()
,Double.longBitsToDouble(long)
-
readLine
public final java.lang.String readLine() throws java.io.IOException
Reads the next line of text from this file. This method successively reads bytes from the file until it reaches the end of a line of text.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.
- Specified by:
readLine
in interfacejava.io.DataInput
- Returns:
- the next line of text from this file.
- Throws:
java.io.IOException
- if an I/O error occurs.
-
readUTF
public final java.lang.String readUTF() throws java.io.IOException
Reads in a string from this file. The string has been encoded using a modified UTF-8 format.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.
- Specified by:
readUTF
in interfacejava.io.DataInput
- Returns:
- a Unicode string.
- Throws:
java.io.EOFException
- if this file reaches the end before reading all the bytes.java.io.IOException
- if an I/O error occurs.java.io.UTFDataFormatException
- if the bytes do not represent valid UTF-8 encoding of a Unicode string.- See Also:
readUnsignedShort()
-
writeBoolean
public final void writeBoolean(boolean v) throws java.io.IOException
Writes aboolean
to the file as a 1-byte value. The valuetrue
is written out as the value(byte)1
; the valuefalse
is written out as the value(byte)0
.- Specified by:
writeBoolean
in interfacejava.io.DataOutput
- Parameters:
v
- aboolean
value to be written.- Throws:
java.io.IOException
- if an I/O error occurs.
-
writeByte
public final void writeByte(int v) throws java.io.IOException
Writes abyte
to the file as a 1-byte value.- Specified by:
writeByte
in interfacejava.io.DataOutput
- Parameters:
v
- abyte
value to be written.- Throws:
java.io.IOException
- if an I/O error occurs.
-
writeShort
public final void writeShort(int v) throws java.io.IOException
Writes ashort
to the file as two bytes, high byte first.- Specified by:
writeShort
in interfacejava.io.DataOutput
- Parameters:
v
- ashort
to be written.- Throws:
java.io.IOException
- if an I/O error occurs.
-
writeChar
public final void writeChar(int v) throws java.io.IOException
Writes achar
to the file as a 2-byte value, high byte first.- Specified by:
writeChar
in interfacejava.io.DataOutput
- Parameters:
v
- achar
value to be written.- Throws:
java.io.IOException
- if an I/O error occurs.
-
writeInt
public final void writeInt(int v) throws java.io.IOException
Writes anint
to the file as four bytes, high byte first.- Specified by:
writeInt
in interfacejava.io.DataOutput
- Parameters:
v
- anint
to be written.- Throws:
java.io.IOException
- if an I/O error occurs.
-
writeLong
public final void writeLong(long v) throws java.io.IOException
Writes along
to the file as eight bytes, high byte first.- Specified by:
writeLong
in interfacejava.io.DataOutput
- Parameters:
v
- along
to be written.- Throws:
java.io.IOException
- if an I/O error occurs.
-
writeFloat
public final void writeFloat(float v) throws java.io.IOException
Converts the float argument to anint
using thefloatToIntBits
method in classFloat
, and then writes thatint
value to the file as a 4-byte quantity, high byte first.- Specified by:
writeFloat
in interfacejava.io.DataOutput
- Parameters:
v
- afloat
value to be written.- Throws:
java.io.IOException
- if an I/O error occurs.- See Also:
Float.floatToIntBits(float)
-
writeDouble
public final void writeDouble(double v) throws java.io.IOException
Converts the double argument to along
using thedoubleToLongBits
method in classDouble
, and then writes thatlong
value to the file as an 8-byte quantity, high byte first.- Specified by:
writeDouble
in interfacejava.io.DataOutput
- Parameters:
v
- adouble
value to be written.- Throws:
java.io.IOException
- if an I/O error occurs.- See Also:
Double.doubleToLongBits(double)
-
writeBytes
public final void writeBytes(java.lang.String s) throws java.io.IOException
Writes the string to the file as a sequence of bytes. Each character in the string is written out, in sequence, by discarding its high eight bits.- Specified by:
writeBytes
in interfacejava.io.DataOutput
- Parameters:
s
- a string of bytes to be written.- Throws:
java.io.IOException
- if an I/O error occurs.
-
writeChars
public final void writeChars(java.lang.String s) throws java.io.IOException
Writes a string to the file as a sequence of characters. Each character is written to the data output stream as if by thewriteChar
method.- Specified by:
writeChars
in interfacejava.io.DataOutput
- Parameters:
s
- aString
value to be written.- Throws:
java.io.IOException
- if an I/O error occurs.- See Also:
writeChar(int)
-
writeUTF
public final void writeUTF(java.lang.String str) throws java.io.IOException
Writes a string to the file using UTF-8 encoding in a machine-independent manner.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.- Specified by:
writeUTF
in interfacejava.io.DataOutput
- Parameters:
str
- a string to be written.- Throws:
java.io.IOException
- if an I/O error occurs.
-
-