--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/io/RandomAccessFile.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,1125 @@
+/*
+ * Copyright 1994-2007 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.io;
+
+import java.nio.channels.FileChannel;
+import sun.nio.ch.FileChannelImpl;
+
+
+/**
+ * Instances of this class support both reading and writing to a
+ * random access file. A random access file behaves like a large
+ * array of bytes stored in the file system. There is a kind of cursor,
+ * or index into the implied array, called the <em>file pointer</em>;
+ * input operations read bytes starting at the file pointer and advance
+ * the file pointer past the bytes read. If the random access file is
+ * created in read/write mode, then output operations are also available;
+ * output operations write bytes starting at the file pointer and advance
+ * the file pointer past the bytes written. Output operations that write
+ * past the current end of the implied array cause the array to be
+ * extended. The file pointer can be read by the
+ * <code>getFilePointer</code> method and set by the <code>seek</code>
+ * method.
+ * <p>
+ * 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</code> (which is a kind of
+ * <code>IOException</code>) is thrown. If any byte cannot be read for
+ * any reason other than end-of-file, an <code>IOException</code> other
+ * than <code>EOFException</code> is thrown. In particular, an
+ * <code>IOException</code> 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 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.
+ *
+ * <p> The <tt>mode</tt> argument specifies the access mode with which the
+ * file is to be opened. The permitted values and their meanings are as
+ * specified for the <a
+ * href="#mode"><tt>RandomAccessFile(File,String)</tt></a> constructor.
+ *
+ * <p>
+ * If there is a security manager, its <code>checkRead</code> method
+ * is called with the <code>name</code> 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</code> method
+ * is also called with the <code>name</code> argument
+ * as its argument to see if write access to the file is allowed.
+ *
+ * @param name the system-dependent filename
+ * @param mode the access <a href="#mode">mode</a>
+ * @exception IllegalArgumentException if the mode argument is not equal
+ * to one of <tt>"r"</tt>, <tt>"rw"</tt>, <tt>"rws"</tt>, or
+ * <tt>"rwd"</tt>
+ * @exception FileNotFoundException
+ * if the mode is <tt>"r"</tt> but the given string does not
+ * denote an existing regular file, or if the mode begins with
+ * <tt>"rw"</tt> 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</code> method denies read access to the file
+ * or the mode is "rw" and the security manager's
+ * <code>checkWrite</code> 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.
+ *
+ * <a name="mode"><p> The <tt>mode</tt> argument specifies the access mode
+ * in which the file is to be opened. The permitted values and their
+ * meanings are:
+ *
+ * <blockquote><table summary="Access mode permitted values and meanings">
+ * <tr><th><p align="left">Value</p></th><th><p align="left">Meaning</p></th></tr>
+ * <tr><td valign="top"><tt>"r"</tt></td>
+ * <td> Open for reading only. Invoking any of the <tt>write</tt>
+ * methods of the resulting object will cause an {@link
+ * java.io.IOException} to be thrown. </td></tr>
+ * <tr><td valign="top"><tt>"rw"</tt></td>
+ * <td> Open for reading and writing. If the file does not already
+ * exist then an attempt will be made to create it. </td></tr>
+ * <tr><td valign="top"><tt>"rws"</tt></td>
+ * <td> Open for reading and writing, as with <tt>"rw"</tt>, and also
+ * require that every update to the file's content or metadata be
+ * written synchronously to the underlying storage device. </td></tr>
+ * <tr><td valign="top"><tt>"rwd" </tt></td>
+ * <td> Open for reading and writing, as with <tt>"rw"</tt>, and also
+ * require that every update to the file's content be written
+ * synchronously to the underlying storage device. </td></tr>
+ * </table></blockquote>
+ *
+ * The <tt>"rws"</tt> and <tt>"rwd"</tt> 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
+ * <tt>true</tt> and <tt>false</tt>, 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.
+ *
+ * <p> The <tt>"rwd"</tt> mode can be used to reduce the number of I/O
+ * operations performed. Using <tt>"rwd"</tt> only requires updates to the
+ * file's content to be written to storage; using <tt>"rws"</tt> 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.
+ *
+ * <p> If there is a security manager, its <code>checkRead</code> method is
+ * called with the pathname of the <code>file</code> 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</code> 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
+ * <a href="#mode">above</a>
+ * @exception IllegalArgumentException if the mode argument is not equal
+ * to one of <tt>"r"</tt>, <tt>"rw"</tt>, <tt>"rws"</tt>, or
+ * <tt>"rwd"</tt>
+ * @exception FileNotFoundException
+ * if the mode is <tt>"r"</tt> but the given file object does
+ * not denote an existing regular file, or if the mode begins
+ * with <tt>"rw"</tt> 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</code> method denies read access to the file
+ * or the mode is "rw" and the security manager's
+ * <code>checkWrite</code> 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.incrementAndGetUseCount();
+ open(name, imode);
+ }
+
+ /**
+ * Returns the opaque file descriptor object associated with this
+ * stream. </p>
+ *
+ * @return the file descriptor object associated with this stream.
+ * @exception IOException if an I/O error occurs.
+ * @see java.io.FileDescriptor
+ */
+ public final FileDescriptor getFD() throws IOException {
+ if (fd != null) return fd;
+ throw new IOException();
+ }
+
+ /**
+ * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
+ * object associated with this file.
+ *
+ * <p> The {@link java.nio.channels.FileChannel#position()
+ * </code>position<code>} 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, true, rw, this);
+
+ /*
+ * FileDescriptor could be shared by FileInputStream or
+ * FileOutputStream.
+ * Ensure that FD is GC'ed only when all the streams/channels
+ * are done using it.
+ * Increment fd's use count. Invoking the channel's close()
+ * method will result in decrementing the use count set for
+ * the channel.
+ */
+ fd.incrementAndGetUseCount();
+ }
+ 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</code>
+ * is true, else the file is opened as read-only.
+ * If the <code>name</code> 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</code>). This
+ * method blocks if no input is yet available.
+ * <p>
+ * Although <code>RandomAccessFile</code> is not a subclass of
+ * <code>InputStream</code>, this method behaves in exactly the same
+ * way as the {@link InputStream#read()} method of
+ * <code>InputStream</code>.
+ *
+ * @return the next byte of data, or <code>-1</code> 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 native int read() 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 native int readBytes(byte b[], int off, int len) throws IOException;
+
+ /**
+ * Reads up to <code>len</code> bytes of data from this file into an
+ * array of bytes. This method blocks until at least one byte of input
+ * is available.
+ * <p>
+ * Although <code>RandomAccessFile</code> is not a subclass of
+ * <code>InputStream</code>, this method behaves in exactly the
+ * same way as the {@link InputStream#read(byte[], int, int)} method of
+ * <code>InputStream</code>.
+ *
+ * @param b the buffer into which the data is read.
+ * @param off the start offset in array <code>b</code>
+ * 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</code> 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</code> is <code>null</code>.
+ * @exception IndexOutOfBoundsException If <code>off</code> is negative,
+ * <code>len</code> is negative, or <code>len</code> is greater than
+ * <code>b.length - off</code>
+ */
+ public int read(byte b[], int off, int len) throws IOException {
+ return readBytes(b, off, len);
+ }
+
+ /**
+ * Reads up to <code>b.length</code> bytes of data from this file
+ * into an array of bytes. This method blocks until at least one byte
+ * of input is available.
+ * <p>
+ * Although <code>RandomAccessFile</code> is not a subclass of
+ * <code>InputStream</code>, this method behaves in exactly the
+ * same way as the {@link InputStream#read(byte[])} method of
+ * <code>InputStream</code>.
+ *
+ * @param b the buffer into which the data is read.
+ * @return the total number of bytes read into the buffer, or
+ * <code>-1</code> 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</code> is <code>null</code>.
+ */
+ public int read(byte b[]) throws IOException {
+ return readBytes(b, 0, b.length);
+ }
+
+ /**
+ * Reads <code>b.length</code> 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</code> 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</code> bytes of input discarding the
+ * skipped bytes.
+ * <p>
+ *
+ * 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</code> bytes have been skipped is only one
+ * possibility. This method never throws an <code>EOFException</code>.
+ * The actual number of bytes skipped is returned. If <code>n</code>
+ * 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</code> to be written.
+ * @exception IOException if an I/O error occurs.
+ */
+ public native void write(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 native void writeBytes(byte b[], int off, int len) throws IOException;
+
+ /**
+ * Writes <code>b.length</code> 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</code> bytes from the specified byte array
+ * starting at offset <code>off</code> 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</code> is less than
+ * <code>0</code> 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.
+ *
+ * <p> If the present length of the file as returned by the
+ * <code>length</code> method is greater than the <code>newLength</code>
+ * argument then the file will be truncated. In this case, if the file
+ * offset as returned by the <code>getFilePointer</code> method is greater
+ * than <code>newLength</code> then after this method returns the offset
+ * will be equal to <code>newLength</code>.
+ *
+ * <p> If the present length of the file as returned by the
+ * <code>length</code> method is smaller than the <code>newLength</code>
+ * 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.
+ *
+ * <p> 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) {
+ /*
+ * Decrement FD use count associated with the channel. The FD use
+ * count is incremented whenever a new channel is obtained from
+ * this stream.
+ */
+ fd.decrementAndGetUseCount();
+ channel.close();
+ }
+
+ /*
+ * Decrement FD use count associated with this stream.
+ * The count got incremented by FileDescriptor during its construction.
+ */
+ fd.decrementAndGetUseCount();
+ close0();
+ }
+
+ //
+ // Some "reading/writing Java data types" methods stolen from
+ // DataInputStream and DataOutputStream.
+ //
+
+ /**
+ * Reads a <code>boolean</code> from this file. This method reads a
+ * single byte from the file, starting at the current file pointer.
+ * A value of <code>0</code> represents
+ * <code>false</code>. Any other value represents <code>true</code>.
+ * This method blocks until the byte is read, the end of the stream
+ * is detected, or an exception is thrown.
+ *
+ * @return the <code>boolean</code> 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</code>, where
+ * <code>0 <= b <= 255</code>,
+ * then the result is:
+ * <blockquote><pre>
+ * (byte)(b)
+ * </pre></blockquote>
+ * <p>
+ * 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</code>.
+ * @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.
+ * <p>
+ * 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</code> and <code>b2</code>, where each of the two values is
+ * between <code>0</code> and <code>255</code>, inclusive, then the
+ * result is equal to:
+ * <blockquote><pre>
+ * (short)((b1 << 8) | b2)
+ * </pre></blockquote>
+ * <p>
+ * 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</code> and <code>b2</code>, where
+ * <code>0 <= b1, b2 <= 255</code>,
+ * then the result is equal to:
+ * <blockquote><pre>
+ * (b1 << 8) | b2
+ * </pre></blockquote>
+ * <p>
+ * 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</code> and <code>b2</code>, where
+ * <code>0 <= b1, b2 <= 255</code>,
+ * then the result is equal to:
+ * <blockquote><pre>
+ * (char)((b1 << 8) | b2)
+ * </pre></blockquote>
+ * <p>
+ * 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</code>.
+ * @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>,
+ * <code>b2</code>, <code>b3</code>, and <code>b4</code>, where
+ * <code>0 <= b1, b2, b3, b4 <= 255</code>,
+ * then the result is equal to:
+ * <blockquote><pre>
+ * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4
+ * </pre></blockquote>
+ * <p>
+ * 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</code>.
+ * @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>, <code>b2</code>, <code>b3</code>,
+ * <code>b4</code>, <code>b5</code>, <code>b6</code>,
+ * <code>b7</code>, and <code>b8,</code> where:
+ * <blockquote><pre>
+ * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
+ * </pre></blockquote>
+ * <p>
+ * then the result is equal to:
+ * <p><blockquote><pre>
+ * ((long)b1 << 56) + ((long)b2 << 48)
+ * + ((long)b3 << 40) + ((long)b4 << 32)
+ * + ((long)b5 << 24) + ((long)b6 << 16)
+ * + ((long)b7 << 8) + b8
+ * </pre></blockquote>
+ * <p>
+ * 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</code>.
+ * @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</code> from this file. This method reads an
+ * <code>int</code> value, starting at the current file pointer,
+ * as if by the <code>readInt</code> method
+ * and then converts that <code>int</code> to a <code>float</code>
+ * using the <code>intBitsToFloat</code> method in class
+ * <code>Float</code>.
+ * <p>
+ * 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</code>.
+ * @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</code> from this file. This method reads a
+ * <code>long</code> value, starting at the current file pointer,
+ * as if by the <code>readLong</code> method
+ * and then converts that <code>long</code> to a <code>double</code>
+ * using the <code>longBitsToDouble</code> method in
+ * class <code>Double</code>.
+ * <p>
+ * 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</code>.
+ * @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.
+ *
+ * <p> A line of text is terminated by a carriage-return character
+ * (<code>'\r'</code>), a newline character (<code>'\n'</code>), 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.
+ *
+ * <p> 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
+ * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
+ * format.
+ * <p>
+ * The first two bytes are read, starting from the current file
+ * pointer, as if by
+ * <code>readUnsignedShort</code>. 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.
+ * <p>
+ * 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</code> to the file as a one-byte value. The
+ * value <code>true</code> is written out as the value
+ * <code>(byte)1</code>; the value <code>false</code> is written out
+ * as the value <code>(byte)0</code>. The write starts at
+ * the current position of the file pointer.
+ *
+ * @param v a <code>boolean</code> 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</code> to the file as a one-byte value. The
+ * write starts at the current position of the file pointer.
+ *
+ * @param v a <code>byte</code> 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</code> 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</code> 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</code> 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</code> 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</code> 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</code> 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</code> 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</code> 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</code> using the
+ * <code>floatToIntBits</code> method in class <code>Float</code>,
+ * and then writes that <code>int</code> 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</code> 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</code> using the
+ * <code>doubleToLongBits</code> method in class <code>Double</code>,
+ * and then writes that <code>long</code> 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</code> 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.
+ */
+ 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</code> method. The write starts at the current
+ * position of the file pointer.
+ *
+ * @param s a <code>String</code> 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
+ * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
+ * encoding in a machine-independent manner.
+ * <p>
+ * First, two bytes are written to the file, starting at the
+ * current file pointer, as if by the
+ * <code>writeShort</code> 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();
+ }
+}