public class XRandomAccessFile
extends java.lang.Object
implements java.io.DataOutput, java.io.DataInput
Constructor and Description |
---|
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.
|
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 the
XFile
argument. |
Modifier and Type | Method and 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 to
b.length bytes of data from this file
into an array of bytes. |
int |
read(byte[] b,
int off,
int len)
Reads up to
len bytes of data from this file into
an array of bytes. |
boolean |
readBoolean()
Reads a
boolean 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 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)
Sets the offset from the beginning of this file at which
the next read or write occurs.
|
int |
skipBytes(int n)
Skips exactly
n bytes of input. |
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)
Writes the specified byte to this 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(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.
|
public XRandomAccessFile(XFile xf, java.lang.String mode) throws java.io.IOException
XFile
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.xf
- the XFile object.mode
- the access mode.java.lang.IllegalArgumentException
- if the mode
argument is not equal to "r"
or
to "rw"
.java.io.IOException
- if an I/O error occurs.public XRandomAccessFile(java.lang.String name, java.lang.String mode) throws java.io.IOException
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.
name
- the native or URL file name.mode
- the access mode.java.lang.IllegalArgumentException
- if the mode
argument is not equal to "r"
or to
"rw"
.java.io.IOException
- if an I/O error occurs.public int read() throws java.io.IOException
-1
if the
end of the file is reached.java.io.IOException
- if an I/O error occurs.public int read(byte[] b, int off, int len) throws java.io.IOException
len
bytes of data from this file into
an array of bytes.b
- the buffer into which the data is read.off
- the start offset of the data.len
- the maximum number of bytes read.-1
if there is no more data because
the end of the file has been reached.java.io.IOException
- if an I/O error occurs.public int read(byte[] b) throws java.io.IOException
b.length
bytes of data from this file
into an array of bytes.b
- the buffer into which the data is read.-1
if there is no more data because
the end of this file has been reached.java.io.IOException
- if an I/O error occurs.public final void readFully(byte[] b) throws java.io.IOException
b.length
bytes from this file into the byte
array.readFully
in interface java.io.DataInput
b
- the buffer into which the data is read.java.io.EOFException
- if this file reaches
the end before reading all the bytes.java.io.IOException
- if an I/O error occurs.public final void readFully(byte[] b, int off, int len) throws java.io.IOException
len
bytes from this file into
the byte array.readFully
in interface java.io.DataInput
b
- the buffer into which the data is read.off
- the start offset of the data.len
- the number of bytes to read.java.io.EOFException
- if this file reaches the
end before reading all the bytes.java.io.IOException
- if an I/O error occurs.public int skipBytes(int n) throws java.io.IOException
n
bytes of input.
skipBytes
in interface java.io.DataInput
n
- the number of bytes to be skipped.n
.java.io.EOFException
- if this file reaches the end
before skipping all the bytes.java.io.IOException
- if an I/O error occurs.public void write(int b) throws java.io.IOException
write
in interface java.io.DataOutput
b
- the byte
to be written.java.io.IOException
- if an I/O error occurs.public void write(byte[] b) throws java.io.IOException
b.length
bytes from the specified byte array
starting at offset off
to this file.write
in interface java.io.DataOutput
b
- the data.java.io.IOException
- if an I/O error occurs.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.write
in interface java.io.DataOutput
b
- the data.off
- the start offset in the data.len
- the number of bytes to write.java.io.IOException
- if an I/O error occurs.public long getFilePointer() throws java.io.IOException
java.io.IOException
- if an I/O error occurs.public void seek(long pos) throws java.io.IOException
pos
- the absolute position.java.io.IOException
- if an I/O error occurs.public long length() throws java.io.IOException
java.io.IOException
- if an I/O error occurs.public void flush() throws java.io.IOException
java.io.IOException
- if an I/O error occurs.public void close() throws java.io.IOException
java.io.IOException
- if an I/O error occurs.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.readBoolean
in interface java.io.DataInput
boolean
value read.java.io.EOFException
- if this file has reached the end.java.io.IOException
- if an I/O error occurs.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.
readByte
in interface java.io.DataInput
byte
.java.io.EOFException
- if this file has reached the end.java.io.IOException
- if an I/O error occurs.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.
readUnsignedByte
in interface java.io.DataInput
java.io.EOFException
- if this file has reached the end.java.io.IOException
- if an I/O error occurs.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.
readShort
in interface java.io.DataInput
java.io.EOFException
- if this file reaches the end before reading
two bytes.java.io.IOException
- if an I/O error occurs.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.
readUnsignedShort
in interface java.io.DataInput
java.io.EOFException
- if this file reaches the end before reading
two bytes.java.io.IOException
- if an I/O error occurs.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.
readChar
in interface java.io.DataInput
java.io.EOFException
- if this file reaches the end before reading
two bytes.java.io.IOException
- if an I/O error occurs.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.
readInt
in interface java.io.DataInput
int
.java.io.EOFException
- if this file reaches the end before reading
four bytes.java.io.IOException
- if an I/O error occurs.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.
readLong
in interface java.io.DataInput
long
.java.io.EOFException
- if this file reaches the end before reading
eight bytes.java.io.IOException
- if an I/O error occurs.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.
readFloat
in interface java.io.DataInput
float
.java.io.EOFException
- if this file reaches the end before reading
four bytes.java.io.IOException
- if an I/O error occurs.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.
readDouble
in interface java.io.DataInput
double
.java.io.EOFException
- if this file reaches the end before reading
eight bytes.java.io.IOException
- if an I/O error occurs.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.
readLine
in interface java.io.DataInput
java.io.IOException
- if an I/O error occurs.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.
readUTF
in interface java.io.DataInput
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.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
.writeBoolean
in interface java.io.DataOutput
v
- a boolean
value to be written.java.io.IOException
- if an I/O error occurs.public final void writeByte(int v) throws java.io.IOException
byte
to the file as a 1-byte value.writeByte
in interface java.io.DataOutput
v
- a byte
value to be written.java.io.IOException
- if an I/O error occurs.public final void writeShort(int v) throws java.io.IOException
short
to the file as two bytes, high byte first.writeShort
in interface java.io.DataOutput
v
- a short
to be written.java.io.IOException
- if an I/O error occurs.public final void writeChar(int v) throws java.io.IOException
char
to the file as a 2-byte value, high
byte first.writeChar
in interface java.io.DataOutput
v
- a char
value to be written.java.io.IOException
- if an I/O error occurs.public final void writeInt(int v) throws java.io.IOException
int
to the file as four bytes, high byte first.writeInt
in interface java.io.DataOutput
v
- an int
to be written.java.io.IOException
- if an I/O error occurs.public final void writeLong(long v) throws java.io.IOException
long
to the file as eight bytes, high byte first.writeLong
in interface java.io.DataOutput
v
- a long
to be written.java.io.IOException
- if an I/O error occurs.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.writeFloat
in interface java.io.DataOutput
v
- a float
value to be written.java.io.IOException
- if an I/O error occurs.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.writeDouble
in interface java.io.DataOutput
v
- a double
value to be written.java.io.IOException
- if an I/O error occurs.Double.doubleToLongBits(double)
public final void writeBytes(java.lang.String s) throws java.io.IOException
writeBytes
in interface java.io.DataOutput
s
- a string of bytes to be written.java.io.IOException
- if an I/O error occurs.public final void writeChars(java.lang.String s) throws java.io.IOException
writeChar
method.writeChars
in interface java.io.DataOutput
s
- a String
value to be written.java.io.IOException
- if an I/O error occurs.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.
writeUTF
in interface java.io.DataOutput
str
- a string to be written.java.io.IOException
- if an I/O error occurs.