* It is generally true of all the reading routines in this class that * if end-of-file is reached before the desired number of bytes has been * read, an {@code EOFException} (which is a kind of * {@code IOException}) is thrown. If any byte cannot be read for * any reason other than end-of-file, an {@code IOException} other * than {@code EOFException} is thrown. In particular, an * {@code IOException} may be thrown if the stream has been closed. * * @author unascribed * @since JDK1.0 */ public class RandomAccessFile implements DataOutput, DataInput, Closeable { private FileDescriptor fd; private FileChannel channel = null; private boolean rw; private final String path; private Object closeLock = new Object(); private volatile boolean closed = false; private static final int O_RDONLY = 1; private static final int O_RDWR = 2; private static final int O_SYNC = 4; private static final int O_DSYNC = 8; /** * Creates a random access file stream to read from, and optionally * to write to, a file with the specified name. A new * {@link FileDescriptor} object is created to represent the * connection to the file. * *
The mode argument specifies the access mode with which the * file is to be opened. The permitted values and their meanings are as * specified for the RandomAccessFile(File,String) constructor. * *
* If there is a security manager, its {@code checkRead} method
* is called with the {@code name} argument
* as its argument to see if read access to the file is allowed.
* If the mode allows writing, the security manager's
* {@code checkWrite} method
* is also called with the {@code name} argument
* as its argument to see if write access to the file is allowed.
*
* @param name the system-dependent filename
* @param mode the access mode
* @exception IllegalArgumentException if the mode argument is not equal
* to one of "r", "rw", "rws", or
* "rwd"
* @exception FileNotFoundException
* if the mode is "r" but the given string does not
* denote an existing regular file, or if the mode begins with
* "rw" but the given string does not denote an
* existing, writable regular file and a new regular file of
* that name cannot be created, or if some other error occurs
* while opening or creating the file
* @exception SecurityException if a security manager exists and its
* {@code checkRead} method denies read access to the file
* or the mode is "rw" and the security manager's
* {@code checkWrite} method denies write access to the file
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkRead(java.lang.String)
* @see java.lang.SecurityManager#checkWrite(java.lang.String)
* @revised 1.4
* @spec JSR-51
*/
public RandomAccessFile(String name, String mode)
throws FileNotFoundException
{
this(name != null ? new File(name) : null, mode);
}
/**
* Creates a random access file stream to read from, and optionally to
* write to, the file specified by the {@link File} argument. A new {@link
* FileDescriptor} object is created to represent this file connection.
*
* The mode argument specifies the access mode
* in which the file is to be opened. The permitted values and their
* meanings are:
*
* Value Meaning The "rwd" mode can be used to reduce the number of I/O
* operations performed. Using "rwd" only requires updates to the
* file's content to be written to storage; using "rws" requires
* updates to both the file's content and its metadata to be written, which
* generally requires at least one more low-level I/O operation.
*
* If there is a security manager, its {@code checkRead} method is
* called with the pathname of the {@code file} argument as its
* argument to see if read access to the file is allowed. If the mode
* allows writing, the security manager's {@code checkWrite} method is
* also called with the path argument to see if write access to the file is
* allowed.
*
* @param file the file object
* @param mode the access mode, as described
* above
* @exception IllegalArgumentException if the mode argument is not equal
* to one of "r", "rw", "rws", or
* "rwd"
* @exception FileNotFoundException
* if the mode is "r" but the given file object does
* not denote an existing regular file, or if the mode begins
* with "rw" but the given file object does not denote
* an existing, writable regular file and a new regular file of
* that name cannot be created, or if some other error occurs
* while opening or creating the file
* @exception SecurityException if a security manager exists and its
* {@code checkRead} method denies read access to the file
* or the mode is "rw" and the security manager's
* {@code checkWrite} method denies write access to the file
* @see java.lang.SecurityManager#checkRead(java.lang.String)
* @see java.lang.SecurityManager#checkWrite(java.lang.String)
* @see java.nio.channels.FileChannel#force(boolean)
* @revised 1.4
* @spec JSR-51
*/
public RandomAccessFile(File file, String mode)
throws FileNotFoundException
{
String name = (file != null ? file.getPath() : null);
int imode = -1;
if (mode.equals("r"))
imode = O_RDONLY;
else if (mode.startsWith("rw")) {
imode = O_RDWR;
rw = true;
if (mode.length() > 2) {
if (mode.equals("rws"))
imode |= O_SYNC;
else if (mode.equals("rwd"))
imode |= O_DSYNC;
else
imode = -1;
}
}
if (imode < 0)
throw new IllegalArgumentException("Illegal mode \"" + mode
+ "\" must be one of "
+ "\"r\", \"rw\", \"rws\","
+ " or \"rwd\"");
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkRead(name);
if (rw) {
security.checkWrite(name);
}
}
if (name == null) {
throw new NullPointerException();
}
fd = new FileDescriptor();
fd.attach(this);
this.path = name;
open(name, imode);
}
/**
* Returns the opaque file descriptor object associated with this
* stream. The {@link java.nio.channels.FileChannel#position()
* position} of the returned channel will always be equal to
* this object's file-pointer offset as returned by the {@link
* #getFilePointer getFilePointer} method. Changing this object's
* file-pointer offset, whether explicitly or by reading or writing bytes,
* will change the position of the channel, and vice versa. Changing the
* file's length via this object will change the length seen via the file
* channel, and vice versa.
*
* @return the file channel associated with this file
*
* @since 1.4
* @spec JSR-51
*/
public final FileChannel getChannel() {
synchronized (this) {
if (channel == null) {
channel = FileChannelImpl.open(fd, path, true, rw, this);
}
return channel;
}
}
/**
* Opens a file and returns the file descriptor. The file is
* opened in read-write mode if the O_RDWR bit in {@code mode}
* is true, else the file is opened as read-only.
* If the {@code name} refers to a directory, an IOException
* is thrown.
*
* @param name the name of the file
* @param mode the mode flags, a combination of the O_ constants
* defined above
*/
private native void open(String name, int mode)
throws FileNotFoundException;
// 'Read' primitives
/**
* Reads a byte of data from this file. The byte is returned as an
* integer in the range 0 to 255 ({@code 0x00-0x0ff}). This
* method blocks if no input is yet available.
*
* Although {@code RandomAccessFile} is not a subclass of
* {@code InputStream}, this method behaves in exactly the same
* way as the {@link InputStream#read()} method of
* {@code InputStream}.
*
* @return the next byte of data, or {@code -1} if the end of the
* file has been reached.
* @exception IOException if an I/O error occurs. Not thrown if
* end-of-file has been reached.
*/
public int read() throws IOException {
Object traceHandle = IoTrace.fileReadBegin(path);
int v = read0();
IoTrace.fileReadEnd(traceHandle, v == -1 ? -1 : 1);
return v;
}
private native int read0() throws IOException;
/**
* Reads a sub array as a sequence of bytes.
* @param b the buffer into which the data is read.
* @param off the start offset of the data.
* @param len the number of bytes to read.
* @exception IOException If an I/O error has occurred.
*/
private int readBytes(byte b[], int off, int len) throws IOException {
Object traceHandle = IoTrace.fileReadBegin(path);
int v = readBytes0(b, off, len);
IoTrace.fileReadEnd(traceHandle, v);
return v;
}
private native int readBytes0(byte b[], int off, int len) throws IOException;
/**
* Reads up to {@code len} bytes of data from this file into an
* array of bytes. This method blocks until at least one byte of input
* is available.
*
* Although {@code RandomAccessFile} is not a subclass of
* {@code InputStream}, this method behaves in exactly the
* same way as the {@link InputStream#read(byte[], int, int)} method of
* {@code InputStream}.
*
* @param b the buffer into which the data is read.
* @param off the start offset in array {@code b}
* at which the data is written.
* @param len the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or
* {@code -1} if there is no more data because the end of
* the file has been reached.
* @exception IOException If the first byte cannot be read for any reason
* other than end of file, or if the random access file has been closed, or if
* some other I/O error occurs.
* @exception NullPointerException If {@code b} is {@code null}.
* @exception IndexOutOfBoundsException If {@code off} is negative,
* {@code len} is negative, or {@code len} is greater than
* {@code b.length - off}
*/
public int read(byte b[], int off, int len) throws IOException {
return readBytes(b, off, len);
}
/**
* Reads up to {@code b.length} bytes of data from this file
* into an array of bytes. This method blocks until at least one byte
* of input is available.
*
* Although {@code RandomAccessFile} is not a subclass of
* {@code InputStream}, this method behaves in exactly the
* same way as the {@link InputStream#read(byte[])} method of
* {@code InputStream}.
*
* @param b the buffer into which the data is read.
* @return the total number of bytes read into the buffer, or
* {@code -1} if there is no more data because the end of
* this file has been reached.
* @exception IOException If the first byte cannot be read for any reason
* other than end of file, or if the random access file has been closed, or if
* some other I/O error occurs.
* @exception NullPointerException If {@code b} is {@code null}.
*/
public int read(byte b[]) throws IOException {
return readBytes(b, 0, b.length);
}
/**
* Reads {@code b.length} bytes from this file into the byte
* array, starting at the current file pointer. This method reads
* repeatedly from the file until the requested number of bytes are
* read. This method blocks until the requested number of bytes are
* read, the end of the stream is detected, or an exception is thrown.
*
* @param b the buffer into which the data is read.
* @exception EOFException if this file reaches the end before reading
* all the bytes.
* @exception IOException if an I/O error occurs.
*/
public final void readFully(byte b[]) throws IOException {
readFully(b, 0, b.length);
}
/**
* Reads exactly {@code len} bytes from this file into the byte
* array, starting at the current file pointer. This method reads
* repeatedly from the file until the requested number of bytes are
* read. This method blocks until the requested number of bytes are
* read, the end of the stream is detected, or an exception is thrown.
*
* @param b the buffer into which the data is read.
* @param off the start offset of the data.
* @param len the number of bytes to read.
* @exception EOFException if this file reaches the end before reading
* all the bytes.
* @exception IOException if an I/O error occurs.
*/
public final void readFully(byte b[], int off, int len) throws IOException {
int n = 0;
do {
int count = this.read(b, off + n, len - n);
if (count < 0)
throw new EOFException();
n += count;
} while (n < len);
}
/**
* Attempts to skip over {@code n} bytes of input discarding the
* skipped bytes.
*
*
* This method may skip over some smaller number of bytes, possibly zero.
* This may result from any of a number of conditions; reaching end of
* file before {@code n} bytes have been skipped is only one
* possibility. This method never throws an {@code EOFException}.
* The actual number of bytes skipped is returned. If {@code n}
* is negative, no bytes are skipped.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @exception IOException if an I/O error occurs.
*/
public int skipBytes(int n) throws IOException {
long pos;
long len;
long newpos;
if (n <= 0) {
return 0;
}
pos = getFilePointer();
len = length();
newpos = pos + n;
if (newpos > len) {
newpos = len;
}
seek(newpos);
/* return the actual number of bytes skipped */
return (int) (newpos - pos);
}
// 'Write' primitives
/**
* Writes the specified byte to this file. The write starts at
* the current file pointer.
*
* @param b the {@code byte} to be written.
* @exception IOException if an I/O error occurs.
*/
public void write(int b) throws IOException {
Object traceHandle = IoTrace.fileWriteBegin(path);
write0(b);
IoTrace.fileWriteEnd(traceHandle, 1);
}
private native void write0(int b) throws IOException;
/**
* Writes a sub array as a sequence of bytes.
* @param b the data to be written
* @param off the start offset in the data
* @param len the number of bytes that are written
* @exception IOException If an I/O error has occurred.
*/
private void writeBytes(byte b[], int off, int len) throws IOException {
Object traceHandle = IoTrace.fileWriteBegin(path);
writeBytes0(b, off, len);
IoTrace.fileWriteEnd(traceHandle, len);
}
private native void writeBytes0(byte b[], int off, int len) throws IOException;
/**
* Writes {@code b.length} bytes from the specified byte array
* to this file, starting at the current file pointer.
*
* @param b the data.
* @exception IOException if an I/O error occurs.
*/
public void write(byte b[]) throws IOException {
writeBytes(b, 0, b.length);
}
/**
* Writes {@code len} bytes from the specified byte array
* starting at offset {@code off} to this file.
*
* @param b the data.
* @param off the start offset in the data.
* @param len the number of bytes to write.
* @exception IOException if an I/O error occurs.
*/
public void write(byte b[], int off, int len) throws IOException {
writeBytes(b, off, len);
}
// 'Random access' stuff
/**
* Returns the current offset in this file.
*
* @return the offset from the beginning of the file, in bytes,
* at which the next read or write occurs.
* @exception IOException if an I/O error occurs.
*/
public native long getFilePointer() throws IOException;
/**
* Sets the file-pointer offset, measured from the beginning of this
* file, at which the next read or write occurs. The offset may be
* set beyond the end of the file. Setting the offset beyond the end
* of the file does not change the file length. The file length will
* change only by writing after the offset has been set beyond the end
* of the file.
*
* @param pos the offset position, measured in bytes from the
* beginning of the file, at which to set the file
* pointer.
* @exception IOException if {@code pos} is less than
* {@code 0} or if an I/O error occurs.
*/
public native void seek(long pos) throws IOException;
/**
* Returns the length of this file.
*
* @return the length of this file, measured in bytes.
* @exception IOException if an I/O error occurs.
*/
public native long length() throws IOException;
/**
* Sets the length of this file.
*
* If the present length of the file as returned by the
* {@code length} method is greater than the {@code newLength}
* argument then the file will be truncated. In this case, if the file
* offset as returned by the {@code getFilePointer} method is greater
* than {@code newLength} then after this method returns the offset
* will be equal to {@code newLength}.
*
* If the present length of the file as returned by the
* {@code length} method is smaller than the {@code newLength}
* argument then the file will be extended. In this case, the contents of
* the extended portion of the file are not defined.
*
* @param newLength The desired length of the file
* @exception IOException If an I/O error occurs
* @since 1.2
*/
public native void setLength(long newLength) throws IOException;
/**
* Closes this random access file stream and releases any system
* resources associated with the stream. A closed random access
* file cannot perform input or output operations and cannot be
* reopened.
*
* If this file has an associated channel then the channel is closed
* as well.
*
* @exception IOException if an I/O error occurs.
*
* @revised 1.4
* @spec JSR-51
*/
public void close() throws IOException {
synchronized (closeLock) {
if (closed) {
return;
}
closed = true;
}
if (channel != null) {
channel.close();
}
fd.closeAll(new Closeable() {
public void close() throws IOException {
close0();
}
});
}
//
// Some "reading/writing Java data types" methods stolen from
// DataInputStream and DataOutputStream.
//
/**
* Reads a {@code boolean} from this file. This method reads a
* single byte from the file, starting at the current file pointer.
* A value of {@code 0} represents
* {@code false}. Any other value represents {@code true}.
* This method blocks until the byte is read, the end of the stream
* is detected, or an exception is thrown.
*
* @return the {@code boolean} value read.
* @exception EOFException if this file has reached the end.
* @exception IOException if an I/O error occurs.
*/
public final boolean readBoolean() throws IOException {
int ch = this.read();
if (ch < 0)
throw new EOFException();
return (ch != 0);
}
/**
* Reads a signed eight-bit value from this file. This method reads a
* byte from the file, starting from the current file pointer.
* If the byte read is {@code b}, where
*
* This method blocks until the byte is read, the end of the stream
* is detected, or an exception is thrown.
*
* @return the next byte of this file as a signed eight-bit
* {@code byte}.
* @exception EOFException if this file has reached the end.
* @exception IOException if an I/O error occurs.
*/
public final byte readByte() throws IOException {
int ch = this.read();
if (ch < 0)
throw new EOFException();
return (byte)(ch);
}
/**
* Reads an unsigned eight-bit number from this file. This method reads
* a byte from this file, starting at the current file pointer,
* and returns that byte.
*
* This method blocks until the byte is read, the end of the stream
* is detected, or an exception is thrown.
*
* @return the next byte of this file, interpreted as an unsigned
* eight-bit number.
* @exception EOFException if this file has reached the end.
* @exception IOException if an I/O error occurs.
*/
public final int readUnsignedByte() throws IOException {
int ch = this.read();
if (ch < 0)
throw new EOFException();
return ch;
}
/**
* Reads a signed 16-bit number from this file. The method reads two
* bytes from this file, starting at the current file pointer.
* If the two bytes read, in order, are
* {@code b1} and {@code b2}, where each of the two values is
* between {@code 0} and {@code 255}, inclusive, then the
* result is equal to:
*
* This method blocks until the two bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next two bytes of this file, interpreted as a signed
* 16-bit number.
* @exception EOFException if this file reaches the end before reading
* two bytes.
* @exception IOException if an I/O error occurs.
*/
public final short readShort() throws IOException {
int ch1 = this.read();
int ch2 = this.read();
if ((ch1 | ch2) < 0)
throw new EOFException();
return (short)((ch1 << 8) + (ch2 << 0));
}
/**
* Reads an unsigned 16-bit number from this file. This method reads
* two bytes from the file, starting at the current file pointer.
* If the bytes read, in order, are
* {@code b1} and {@code b2}, where
*
* This method blocks until the two bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next two bytes of this file, interpreted as an unsigned
* 16-bit integer.
* @exception EOFException if this file reaches the end before reading
* two bytes.
* @exception IOException if an I/O error occurs.
*/
public final int readUnsignedShort() throws IOException {
int ch1 = this.read();
int ch2 = this.read();
if ((ch1 | ch2) < 0)
throw new EOFException();
return (ch1 << 8) + (ch2 << 0);
}
/**
* Reads a character from this file. This method reads two
* bytes from the file, starting at the current file pointer.
* If the bytes read, in order, are
* {@code b1} and {@code b2}, where
*
* This method blocks until the two bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next two bytes of this file, interpreted as a
* {@code char}.
* @exception EOFException if this file reaches the end before reading
* two bytes.
* @exception IOException if an I/O error occurs.
*/
public final char readChar() throws IOException {
int ch1 = this.read();
int ch2 = this.read();
if ((ch1 | ch2) < 0)
throw new EOFException();
return (char)((ch1 << 8) + (ch2 << 0));
}
/**
* Reads a signed 32-bit integer from this file. This method reads 4
* bytes from the file, starting at the current file pointer.
* If the bytes read, in order, are {@code b1},
* {@code b2}, {@code b3}, and {@code b4}, where
*
* This method blocks until the four bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next four bytes of this file, interpreted as an
* {@code int}.
* @exception EOFException if this file reaches the end before reading
* four bytes.
* @exception IOException if an I/O error occurs.
*/
public final int readInt() throws IOException {
int ch1 = this.read();
int ch2 = this.read();
int ch3 = this.read();
int ch4 = this.read();
if ((ch1 | ch2 | ch3 | ch4) < 0)
throw new EOFException();
return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
}
/**
* Reads a signed 64-bit integer from this file. This method reads eight
* bytes from the file, starting at the current file pointer.
* If the bytes read, in order, are
* {@code b1}, {@code b2}, {@code b3},
* {@code b4}, {@code b5}, {@code b6},
* {@code b7}, and {@code b8,} where:
*
* then the result is equal to:
*
* This method blocks until the eight bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next eight bytes of this file, interpreted as a
* {@code long}.
* @exception EOFException if this file reaches the end before reading
* eight bytes.
* @exception IOException if an I/O error occurs.
*/
public final long readLong() throws IOException {
return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL);
}
/**
* Reads a {@code float} from this file. This method reads an
* {@code int} value, starting at the current file pointer,
* as if by the {@code readInt} method
* and then converts that {@code int} to a {@code float}
* using the {@code intBitsToFloat} method in class
* {@code Float}.
*
* This method blocks until the four bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next four bytes of this file, interpreted as a
* {@code float}.
* @exception EOFException if this file reaches the end before reading
* four bytes.
* @exception IOException if an I/O error occurs.
* @see java.io.RandomAccessFile#readInt()
* @see java.lang.Float#intBitsToFloat(int)
*/
public final float readFloat() throws IOException {
return Float.intBitsToFloat(readInt());
}
/**
* Reads a {@code double} from this file. This method reads a
* {@code long} value, starting at the current file pointer,
* as if by the {@code readLong} method
* and then converts that {@code long} to a {@code double}
* using the {@code longBitsToDouble} method in
* class {@code Double}.
*
* This method blocks until the eight bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next eight bytes of this file, interpreted as a
* {@code double}.
* @exception EOFException if this file reaches the end before reading
* eight bytes.
* @exception IOException if an I/O error occurs.
* @see java.io.RandomAccessFile#readLong()
* @see java.lang.Double#longBitsToDouble(long)
*/
public final double readDouble() throws IOException {
return Double.longBitsToDouble(readLong());
}
/**
* Reads the next line of text from this file. This method successively
* reads bytes from the file, starting at the current file pointer,
* until it reaches a line terminator or the end
* of the file. Each byte is converted into a character by taking the
* byte's value for the lower eight bits of the character and setting the
* high eight bits of the character to zero. This method does not,
* therefore, support the full Unicode character set.
*
* A line of text is terminated by a carriage-return character
* ({@code '\u005Cr'}), a newline character ({@code '\u005Cn'}), a
* carriage-return character immediately followed by a newline character,
* or the end of the file. Line-terminating characters are discarded and
* are not 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 file is reached, or an exception is thrown.
*
* @return the next line of text from this file, or null if end
* of file is encountered before even one byte is read.
* @exception IOException if an I/O error occurs.
*/
public final String readLine() throws IOException {
StringBuffer input = new StringBuffer();
int c = -1;
boolean eol = false;
while (!eol) {
switch (c = read()) {
case -1:
case '\n':
eol = true;
break;
case '\r':
eol = true;
long cur = getFilePointer();
if ((read()) != '\n') {
seek(cur);
}
break;
default:
input.append((char)c);
break;
}
}
if ((c == -1) && (input.length() == 0)) {
return null;
}
return input.toString();
}
/**
* Reads in a string from this file. The string has been encoded
* using a
* modified UTF-8
* format.
*
* The first two bytes are read, starting from the current file
* pointer, as if by
* {@code 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 modified 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.
*
* @return a Unicode string.
* @exception EOFException if this file reaches the end before
* reading all the bytes.
* @exception IOException if an I/O error occurs.
* @exception UTFDataFormatException if the bytes do not represent
* valid modified UTF-8 encoding of a Unicode string.
* @see java.io.RandomAccessFile#readUnsignedShort()
*/
public final String readUTF() throws IOException {
return DataInputStream.readUTF(this);
}
/**
* Writes a {@code boolean} to the file as a one-byte value. The
* value {@code true} is written out as the value
* {@code (byte)1}; the value {@code false} is written out
* as the value {@code (byte)0}. The write starts at
* the current position of the file pointer.
*
* @param v a {@code boolean} value to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeBoolean(boolean v) throws IOException {
write(v ? 1 : 0);
//written++;
}
/**
* Writes a {@code byte} to the file as a one-byte value. The
* write starts at the current position of the file pointer.
*
* @param v a {@code byte} value to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeByte(int v) throws IOException {
write(v);
//written++;
}
/**
* Writes a {@code short} to the file as two bytes, high byte first.
* The write starts at the current position of the file pointer.
*
* @param v a {@code short} to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeShort(int v) throws IOException {
write((v >>> 8) & 0xFF);
write((v >>> 0) & 0xFF);
//written += 2;
}
/**
* Writes a {@code char} to the file as a two-byte value, high
* byte first. The write starts at the current position of the
* file pointer.
*
* @param v a {@code char} value to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeChar(int v) throws IOException {
write((v >>> 8) & 0xFF);
write((v >>> 0) & 0xFF);
//written += 2;
}
/**
* Writes an {@code int} to the file as four bytes, high byte first.
* The write starts at the current position of the file pointer.
*
* @param v an {@code int} to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeInt(int v) throws IOException {
write((v >>> 24) & 0xFF);
write((v >>> 16) & 0xFF);
write((v >>> 8) & 0xFF);
write((v >>> 0) & 0xFF);
//written += 4;
}
/**
* Writes a {@code long} to the file as eight bytes, high byte first.
* The write starts at the current position of the file pointer.
*
* @param v a {@code long} to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeLong(long v) throws IOException {
write((int)(v >>> 56) & 0xFF);
write((int)(v >>> 48) & 0xFF);
write((int)(v >>> 40) & 0xFF);
write((int)(v >>> 32) & 0xFF);
write((int)(v >>> 24) & 0xFF);
write((int)(v >>> 16) & 0xFF);
write((int)(v >>> 8) & 0xFF);
write((int)(v >>> 0) & 0xFF);
//written += 8;
}
/**
* Converts the float argument to an {@code int} using the
* {@code floatToIntBits} method in class {@code Float},
* and then writes that {@code int} value to the file as a
* four-byte quantity, high byte first. The write starts at the
* current position of the file pointer.
*
* @param v a {@code float} value to be written.
* @exception IOException if an I/O error occurs.
* @see java.lang.Float#floatToIntBits(float)
*/
public final void writeFloat(float v) throws IOException {
writeInt(Float.floatToIntBits(v));
}
/**
* Converts the double argument to a {@code long} using the
* {@code doubleToLongBits} method in class {@code Double},
* and then writes that {@code long} value to the file as an
* eight-byte quantity, high byte first. The write starts at the current
* position of the file pointer.
*
* @param v a {@code double} value to be written.
* @exception IOException if an I/O error occurs.
* @see java.lang.Double#doubleToLongBits(double)
*/
public final void writeDouble(double v) throws IOException {
writeLong(Double.doubleToLongBits(v));
}
/**
* 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. The write starts at the current position of
* the file pointer.
*
* @param s a string of bytes to be written.
* @exception IOException if an I/O error occurs.
*/
@SuppressWarnings("deprecation")
public final void writeBytes(String s) throws IOException {
int len = s.length();
byte[] b = new byte[len];
s.getBytes(0, len, b, 0);
writeBytes(b, 0, len);
}
/**
* Writes a string to the file as a sequence of characters. Each
* character is written to the data output stream as if by the
* {@code writeChar} method. The write starts at the current
* position of the file pointer.
*
* @param s a {@code String} value to be written.
* @exception IOException if an I/O error occurs.
* @see java.io.RandomAccessFile#writeChar(int)
*/
public final void writeChars(String s) throws IOException {
int clen = s.length();
int blen = 2*clen;
byte[] b = new byte[blen];
char[] c = new char[clen];
s.getChars(0, clen, c, 0);
for (int i = 0, j = 0; i < clen; i++) {
b[j++] = (byte)(c[i] >>> 8);
b[j++] = (byte)(c[i] >>> 0);
}
writeBytes(b, 0, blen);
}
/**
* Writes a string to the file using
* modified UTF-8
* encoding in a machine-independent manner.
*
* First, two bytes are written to the file, starting at the
* current file pointer, as if by the
* {@code 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 modified UTF-8 encoding
* for each character.
*
* @param str a string to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeUTF(String str) throws IOException {
DataOutputStream.writeUTF(str, this);
}
private static native void initIDs();
private native void close0() throws IOException;
static {
initIDs();
}
}
*
* The "rws" and "rwd" modes work much like the {@link
* java.nio.channels.FileChannel#force(boolean) force(boolean)} method of
* the {@link java.nio.channels.FileChannel} class, passing arguments of
* true and false, respectively, except that they always
* apply to every I/O operation and are therefore often more efficient. If
* the file resides on a local storage device then when an invocation of a
* method of this class returns it is guaranteed that all changes made to
* the file by that invocation will have been written to that device. This
* is useful for ensuring that critical information is not lost in the
* event of a system crash. If the file does not reside on a local device
* then no such guarantee is made.
*
*
*
"r"
* Open for reading only. Invoking any of the write
* methods of the resulting object will cause an {@link
* java.io.IOException} to be thrown. "rw"
* Open for reading and writing. If the file does not already
* exist then an attempt will be made to create it. "rws"
* Open for reading and writing, as with "rw", and also
* require that every update to the file's content or metadata be
* written synchronously to the underlying storage device. "rwd"
* Open for reading and writing, as with "rw", and also
* require that every update to the file's content be written
* synchronously to the underlying storage device. 0 <= b <= 255,
* then the result is:
*
*
* (byte)(b)
*
*
* (short)((b1 << 8) | b2)
* 0 <= b1, b2 <= 255,
* then the result is equal to:
*
*
* (b1 << 8) | b2
* 0 <= b1, b2 <= 255,
* then the result is equal to:
*
*
* (char)((b1 << 8) | b2)
* 0 <= b1, b2, b3, b4 <= 255,
* then the result is equal to:
*
*
* (b1 << 24) | (b2 << 16) + (b3 << 8) + b4
*
*
* 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
*
*
* ((long)b1 << 56) + ((long)b2 << 48)
* + ((long)b3 << 40) + ((long)b4 << 32)
* + ((long)b5 << 24) + ((long)b6 << 16)
* + ((long)b7 << 8) + b8
*