diff options
Diffstat (limited to 'libjava/java/io/RandomAccessFile.java')
| -rw-r--r-- | libjava/java/io/RandomAccessFile.java | 1036 |
1 files changed, 1036 insertions, 0 deletions
diff --git a/libjava/java/io/RandomAccessFile.java b/libjava/java/io/RandomAccessFile.java new file mode 100644 index 0000000..d719a1e --- /dev/null +++ b/libjava/java/io/RandomAccessFile.java @@ -0,0 +1,1036 @@ +/* RandomAccessFile.java -- Class supporting random file I/O + Copyright (C) 1998, 1999, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath 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 for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package java.io; + +import gnu.java.nio.channels.FileChannelImpl; + +import java.nio.channels.FileChannel; + +/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3 + * "The Java Language Specification", ISBN 0-201-63451-1 + * Status: Believe complete and correct to 1.1. + */ + +/** + * This class allows reading and writing of files at random locations. + * Most Java I/O classes are either pure sequential input or output. This + * class fulfills the need to be able to read the bytes of a file in an + * arbitrary order. In addition, this class implements the + * <code>DataInput</code> and <code>DataOutput</code> interfaces to allow + * the reading and writing of Java primitives. + * + * @author Aaron M. Renn (arenn@urbanophile.com) + * @author Tom Tromey (tromey@cygnus.com) + */ +public class RandomAccessFile implements DataOutput, DataInput, Closeable +{ + + // The underlying file. + private FileChannelImpl ch; + private FileDescriptor fd; + // The corresponding input and output streams. + private DataOutputStream out; + private DataInputStream in; + + + /** + * This method initializes a new instance of <code>RandomAccessFile</code> + * to read from the specified <code>File</code> object with the specified + * access mode. The access mode is either "r" for read only access or "rw" + * for read-write access. + * <p> + * Note that a <code>SecurityManager</code> check is made prior to + * opening the file to determine whether or not this file is allowed to + * be read or written. + * + * @param file The <code>File</code> object to read and/or write. + * @param mode "r" for read only or "rw" for read-write access to the file + * + * @exception IllegalArgumentException If <code>mode</code> has an + * illegal value + * @exception SecurityException If the requested access to the file + * is not allowed + * @exception FileNotFoundException If the file is a directory, or + * any other error occurs + */ + public RandomAccessFile (File file, String mode) + throws FileNotFoundException + { + int fdmode; + if (mode.equals("r")) + fdmode = FileChannelImpl.READ; + else if (mode.equals("rw")) + fdmode = FileChannelImpl.READ | FileChannelImpl.WRITE; + else if (mode.equals("rws")) + { + fdmode = (FileChannelImpl.READ | FileChannelImpl.WRITE + | FileChannelImpl.SYNC); + } + else if (mode.equals("rwd")) + { + fdmode = (FileChannelImpl.READ | FileChannelImpl.WRITE + | FileChannelImpl.DSYNC); + } + else + throw new IllegalArgumentException ("invalid mode: " + mode); + + final String fileName = file.getPath(); + + // The obligatory SecurityManager stuff + SecurityManager s = System.getSecurityManager(); + if (s != null) + { + s.checkRead(fileName); + + if ((fdmode & FileChannelImpl.WRITE) != 0) + s.checkWrite(fileName); + } + + ch = FileChannelImpl.create(file, fdmode); + fd = new FileDescriptor(ch); + if ((fdmode & FileChannelImpl.WRITE) != 0) + out = new DataOutputStream (new FileOutputStream (fd)); + else + out = null; + in = new DataInputStream (new FileInputStream (fd)); + } + + /** + * This method initializes a new instance of <code>RandomAccessFile</code> + * to read from the specified file name with the specified access mode. + * The access mode is either "r" for read only access, "rw" for read + * write access, "rws" for synchronized read/write access of both + * content and metadata, or "rwd" for read/write access + * where only content is required to be synchronous. + * <p> + * Note that a <code>SecurityManager</code> check is made prior to + * opening the file to determine whether or not this file is allowed to + * be read or written. + * + * @param fileName The name of the file to read and/or write + * @param mode "r", "rw", "rws", or "rwd" + * + * @exception IllegalArgumentException If <code>mode</code> has an + * illegal value + * @exception SecurityException If the requested access to the file + * is not allowed + * @exception FileNotFoundException If the file is a directory or + * any other error occurs + */ + public RandomAccessFile (String fileName, String mode) + throws FileNotFoundException + { + this (new File(fileName), mode); + } + + /** + * This method closes the file and frees up all file related system + * resources. Since most operating systems put a limit on how many files + * may be opened at any given time, it is a good idea to close all files + * when no longer needed to avoid hitting this limit + */ + public void close () throws IOException + { + ch.close(); + } + + /** + * This method returns a <code>FileDescriptor</code> object that + * represents the native file handle for this file. + * + * @return The <code>FileDescriptor</code> object for this file + * + * @exception IOException If an error occurs + */ + public final FileDescriptor getFD () throws IOException + { + synchronized (this) + { + if (fd == null) + fd = new FileDescriptor (ch); + return fd; + } + } + + /** + * This method returns the current offset in the file at which the next + * read or write will occur + * + * @return The current file position + * + * @exception IOException If an error occurs + */ + public long getFilePointer () throws IOException + { + return ch.position(); + } + + /** + * This method sets the length of the file to the specified length. + * If the currently length of the file is longer than the specified + * length, then the file is truncated to the specified length (the + * file position is set to the end of file in this case). If the + * current length of the file is shorter than the specified length, + * the file is extended with bytes of an undefined value (the file + * position is unchanged in this case). + * <p> + * The file must be open for write access for this operation to succeed. + * + * @param newLen The new length of the file + * + * @exception IOException If an error occurs + */ + public void setLength (long newLen) throws IOException + { + // FIXME: Extending a file should probably be done by one method call. + + // FileChannel.truncate() can only shrink a file. + // To expand it we need to seek forward and write at least one byte. + if (newLen < length()) + ch.truncate (newLen); + else if (newLen > length()) + { + long pos = getFilePointer(); + seek(newLen - 1); + write(0); + seek(pos); + } + } + + /** + * This method returns the length of the file in bytes + * + * @return The length of the file + * + * @exception IOException If an error occurs + */ + public long length () throws IOException + { + return ch.size(); + } + + /** + * This method reads a single byte of data from the file and returns it + * as an integer. + * + * @return The byte read as an int, or -1 if the end of the file was reached. + * + * @exception IOException If an error occurs + */ + public int read () throws IOException + { + return in.read(); + } + + /** + * This method reads bytes from the file into the specified array. The + * bytes are stored starting at the beginning of the array and up to + * <code>buf.length</code> bytes can be read. + * + * @param buffer The buffer to read bytes from the file into + * + * @return The actual number of bytes read or -1 if end of file + * + * @exception IOException If an error occurs + */ + public int read (byte[] buffer) throws IOException + { + return in.read (buffer); + } + + /** + * This methods reads up to <code>len</code> bytes from the file into the + * specified array starting at position <code>offset</code> into the array. + * + * @param buffer The array to read the bytes into + * @param offset The index into the array to start storing bytes + * @param len The requested number of bytes to read + * + * @return The actual number of bytes read, or -1 if end of file + * + * @exception IOException If an error occurs + */ + public int read (byte[] buffer, int offset, int len) throws IOException + { + return in.read (buffer, offset, len); + } + + /** + * This method reads a Java boolean value from an input stream. It does + * so by reading a single byte of data. If that byte is zero, then the + * value returned is <code>false</code> If the byte is non-zero, then + * the value returned is <code>true</code> + * <p> + * This method can read a <code>boolean</code> written by an object + * implementing the + * <code>writeBoolean()</code> method in the <code>DataOutput</code> + * interface. + * + * @return The <code>boolean</code> value read + * + * @exception EOFException If end of file is reached before reading the + * boolean + * @exception IOException If any other error occurs + */ + public final boolean readBoolean () throws IOException + { + return in.readBoolean (); + } + + /** + * This method reads a Java byte value from an input stream. The value + * is in the range of -128 to 127. + * <p> + * This method can read a <code>byte</code> written by an object + * implementing the + * <code>writeByte()</code> method in the <code>DataOutput</code> interface. + * + * @return The <code>byte</code> value read + * + * @exception EOFException If end of file is reached before reading the byte + * @exception IOException If any other error occurs + * + * @see DataOutput + */ + public final byte readByte () throws IOException + { + return in.readByte (); + } + + /** + * This method reads a Java <code>char</code> value from an input stream. + * It operates by reading two bytes from the stream and converting them to + * a single 16-bit Java <code>char</code> The two bytes are stored most + * significant byte first (i.e., "big endian") regardless of the native + * host byte ordering. + * <p> + * As an example, if <code>byte1</code> and <code>byte2</code> represent + * the first + * and second byte read from the stream respectively, they will be + * transformed to a <code>char</code> in the following manner: + * <p> + * <code>(char)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF)</code> + * <p> + * This method can read a <code>char</code> written by an object + * implementing the + * <code>writeChar()</code> method in the <code>DataOutput</code> interface. + * + * @return The <code>char</code> value read + * + * @exception EOFException If end of file is reached before reading the char + * @exception IOException If any other error occurs + * + * @see DataOutput + */ + public final char readChar () throws IOException + { + return in.readChar(); + } + + /** + * This method reads a Java double value from an input stream. It operates + * by first reading a <code>logn</code> value from the stream by calling the + * <code>readLong()</code> method in this interface, then + * converts that <code>long</code> + * to a <code>double</code> using the <code>longBitsToDouble</code> + * method in the class <code>java.lang.Double</code> + * <p> + * This method can read a <code>double</code> written by an object + * implementing the + * <code>writeDouble()</code> method in the <code>DataOutput</code> + * interface. + * + * @return The <code>double</code> value read + * + * @exception EOFException If end of file is reached before reading + * the double + * @exception IOException If any other error occurs + * + * @see java.lang.Double + * @see DataOutput + */ + public final double readDouble () throws IOException + { + return in.readDouble (); + } + + /** + * This method reads a Java float value from an input stream. It operates + * by first reading an <code>int</code> value from the stream by calling the + * <code>readInt()</code> method in this interface, then converts + * that <code>int</code> + * to a <code>float</code> using the <code>intBitsToFloat</code> method in + * the class <code>java.lang.Float</code> + * <p> + * This method can read a <code>float</code> written by an object + * implementing the + * <code>writeFloat()</code> method in the <code>DataOutput</code> interface. + * + * @return The <code>float</code> value read + * + * @exception EOFException If end of file is reached before reading the float + * @exception IOException If any other error occurs + * + * @see java.lang.Float + * @see DataOutput + */ + public final float readFloat () throws IOException + { + return in.readFloat(); + } + + /** + * This method reads raw bytes into the passed array until the array is + * full. Note that this method blocks until the data is available and + * throws an exception if there is not enough data left in the stream to + * fill the buffer + * + * @param buffer The buffer into which to read the data + * + * @exception EOFException If end of file is reached before filling the + * buffer + * @exception IOException If any other error occurs + */ + public final void readFully (byte[] buffer) throws IOException + { + in.readFully(buffer); + } + + /** + * This method reads raw bytes into the passed array <code>buf</code> + * starting + * <code>offset</code> bytes into the buffer. The number of bytes read + * will be + * exactly <code>len</code> Note that this method blocks until the data is + * available and throws an exception if there is not enough data left in + * the stream to read <code>len</code> bytes. + * + * @param buffer The buffer into which to read the data + * @param offset The offset into the buffer to start storing data + * @param count The number of bytes to read into the buffer + * + * @exception EOFException If end of file is reached before filling + * the buffer + * @exception IOException If any other error occurs + */ + public final void readFully (byte[] buffer, int offset, int count) + throws IOException + { + in.readFully (buffer, offset, count); + } + + /** + * This method reads a Java <code>int</code> value from an input stream + * It operates by reading four bytes from the stream and converting them to + * a single Java <code>int</code> The bytes are stored most + * significant byte first (i.e., "big endian") regardless of the native + * host byte ordering. + * <p> + * As an example, if <code>byte1</code> through <code>byte4</code> + * represent the first + * four bytes read from the stream, they will be + * transformed to an <code>int</code> in the following manner: + * <p> + * <code>(int)(((byte1 & 0xFF) << 24) + ((byte2 & 0xFF) << 16) + + * ((byte3 & 0xFF) << 8) + (byte4 & 0xFF)))</code> + * <p> + * The value returned is in the range of 0 to 65535. + * <p> + * This method can read an <code>int</code> written by an object + * implementing the + * <code>writeInt()</code> method in the <code>DataOutput</code> interface. + * + * @return The <code>int</code> value read + * + * @exception EOFException If end of file is reached before reading the int + * @exception IOException If any other error occurs + * + * @see DataOutput + */ + public final int readInt () throws IOException + { + return in.readInt(); + } + + /** + * This method reads the next line of text data from an input stream. + * It operates by reading bytes and converting those bytes to + * <code>char</code> + * values by treating the byte read as the low eight bits of the + * <code>char</code> + * and using <code>0</code> as the high eight bits. Because of this, it does + * not support the full 16-bit Unicode character set. + * <p> + * The reading of bytes ends when either the end of file or a line terminator + * is encountered. The bytes read are then returned as a <code>String</code> + * A line terminator is a byte sequence consisting of either + * <code>\r</code> <code>\n</code> or <code>\r\n</code> These + * termination charaters are + * discarded and are not returned as part of the string. + * <p> + * This method can read data that was written by an object implementing the + * <code>writeLine()</code> method in <code>DataOutput</code> + * + * @return The line read as a <code>String</code> + * + * @exception IOException If an error occurs + * + * @see DataOutput + */ + public final String readLine () throws IOException + { + return in.readLine (); + } + + /** + * This method reads a Java long value from an input stream + * It operates by reading eight bytes from the stream and converting them to + * a single Java <code>long</code> The bytes are stored most + * significant byte first (i.e., "big endian") regardless of the native + * host byte ordering. + * <p> + * As an example, if <code>byte1</code> through <code>byte8</code> + * represent the first + * eight bytes read from the stream, they will be + * transformed to an <code>long</code> in the following manner: + * <p> + * <code> + * (long)((((long)byte1 & 0xFF) << 56) + (((long)byte2 & 0xFF) << 48) + + * (((long)byte3 & 0xFF) << 40) + (((long)byte4 & 0xFF) << 32) + + * (((long)byte5 & 0xFF) << 24) + (((long)byte6 & 0xFF) << 16) + + * (((long)byte7 & 0xFF) << 8) + ((long)byte9 & 0xFF)))</code> + * <p> + * The value returned is in the range of 0 to 65535. + * <p> + * This method can read an <code>long</code> written by an object + * implementing the + * <code>writeLong()</code> method in the <code>DataOutput</code> interface. + * + * @return The <code>long</code> value read + * + * @exception EOFException If end of file is reached before reading the long + * @exception IOException If any other error occurs + * + * @see DataOutput + */ + public final long readLong () throws IOException + { + return in.readLong(); + } + + /** + * This method reads a signed 16-bit value into a Java in from the stream. + * It operates by reading two bytes from the stream and converting them to + * a single 16-bit Java <code>short</code> The two bytes are stored most + * significant byte first (i.e., "big endian") regardless of the native + * host byte ordering. + * <p> + * As an example, if <code>byte1</code> and <code>byte2</code> + * represent the first + * and second byte read from the stream respectively, they will be + * transformed to a <code>short</code> in the following manner: + * <p> + * <code>(short)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF)</code> + * <p> + * The value returned is in the range of -32768 to 32767. + * <p> + * This method can read a <code>short</code> written by an object + * implementing the + * <code>writeShort()</code> method in the <code>DataOutput</code> interface. + * + * @return The <code>short</code> value read + * + * @exception EOFException If end of file is reached before reading the value + * @exception IOException If any other error occurs + * + * @see DataOutput + */ + public final short readShort () throws IOException + { + return in.readShort(); + } + + /** + * This method reads 8 unsigned bits into a Java <code>int</code> value + * from the + * stream. The value returned is in the range of 0 to 255. + * <p> + * This method can read an unsigned byte written by an object implementing + * the <code>writeUnsignedByte()</code> method in the + * <code>DataOutput</code> interface. + * + * @return The unsigned bytes value read as a Java <code>int</code> + * + * @exception EOFException If end of file is reached before reading the value + * @exception IOException If any other error occurs + * + * @see DataOutput + */ + public final int readUnsignedByte () throws IOException + { + return in.readUnsignedByte(); + } + + /** + * This method reads 16 unsigned bits into a Java int value from the stream. + * It operates by reading two bytes from the stream and converting them to + * a single Java <code>int</code> The two bytes are stored most + * significant byte first (i.e., "big endian") regardless of the native + * host byte ordering. + * <p> + * As an example, if <code>byte1</code> and <code>byte2</code> + * represent the first + * and second byte read from the stream respectively, they will be + * transformed to an <code>int</code> in the following manner: + * <p> + * <code>(int)(((byte1 & 0xFF) << 8) + (byte2 & 0xFF))</code> + * <p> + * The value returned is in the range of 0 to 65535. + * <p> + * This method can read an unsigned short written by an object implementing + * the <code>writeUnsignedShort()</code> method in the + * <code>DataOutput</code> interface. + * + * @return The unsigned short value read as a Java <code>int</code> + * + * @exception EOFException If end of file is reached before reading the value + * @exception IOException If any other error occurs + */ + public final int readUnsignedShort () throws IOException + { + return in.readUnsignedShort(); + } + + /** + * This method reads a <code>String</code> from an input stream that + * is encoded in + * a modified UTF-8 format. This format has a leading two byte sequence + * that contains the remaining number of bytes to read. This two byte + * sequence is read using the <code>readUnsignedShort()</code> method of this + * interface. + * <p> + * After the number of remaining bytes have been determined, these bytes + * are read an transformed into <code>char</code> values. + * These <code>char</code> values + * are encoded in the stream using either a one, two, or three byte format. + * The particular format in use can be determined by examining the first + * byte read. + * <p> + * If the first byte has a high order bit of 0 then + * that character consists on only one byte. This character value consists + * of seven bits that are at positions 0 through 6 of the byte. As an + * example, if <code>byte1</code> is the byte read from the stream, it would + * be converted to a <code>char</code> like so: + * <p> + * <code>(char)byte1</code> + * <p> + * If the first byte has <code>110</code> as its high order bits, then the + * character consists of two bytes. The bits that make up the character + * value are in positions 0 through 4 of the first byte and bit positions + * 0 through 5 of the second byte. (The second byte should have + * 10 as its high order bits). These values are in most significant + * byte first (i.e., "big endian") order. + * <p> + * As an example, if <code>byte1</code> and <code>byte2</code> + * are the first two bytes + * read respectively, and the high order bits of them match the patterns + * which indicate a two byte character encoding, then they would be + * converted to a Java <code>char</code> like so: + * <p> + * <code>(char)(((byte1 & 0x1F) << 6) | (byte2 & 0x3F))</code> + * <p> + * If the first byte has a <code>1110</code> as its high order bits, then the + * character consists of three bytes. The bits that make up the character + * value are in positions 0 through 3 of the first byte and bit positions + * 0 through 5 of the other two bytes. (The second and third bytes should + * have <code>10</code> as their high order bits). These values are in most + * significant byte first (i.e., "big endian") order. + * <p> + * As an example, if <code>byte1</code> <code>byte2</code> + * and <code>byte3</code> are the + * three bytes read, and the high order bits of them match the patterns + * which indicate a three byte character encoding, then they would be + * converted to a Java <code>char</code> like so: + * <p> + * <code>(char)(((byte1 & 0x0F) << 12) | ((byte2 & 0x3F) << 6) | + * (byte3 & 0x3F))</code> + * <p> + * Note that all characters are encoded in the method that requires the + * fewest number of bytes with the exception of the character with the + * value of <code>\u0000</code> which is encoded as two bytes. This is + * a modification of the UTF standard used to prevent C language style + * <code>NUL</code> values from appearing in the byte stream. + * <p> + * This method can read data that was written by an object implementing the + * <code>writeUTF()</code> method in <code>DataOutput</code> + * + * @return The <code>String</code> read + * + * @exception EOFException If end of file is reached before reading the + * String + * @exception UTFDataFormatException If the data is not in UTF-8 format + * @exception IOException If any other error occurs + * + * @see DataOutput + */ + public final String readUTF () throws IOException + { + return in.readUTF(); + } + + /** + * This method sets the current file position to the specified offset + * from the beginning of the file. Note that some operating systems will + * allow the file pointer to be set past the current end of the file. + * + * @param pos The offset from the beginning of the file at which to set + * the file pointer + * + * @exception IOException If an error occurs + */ + public void seek (long pos) throws IOException + { + ch.position(pos); + } + + /** + * This method attempts to skip and discard the specified number of bytes + * in the input stream. It may actually skip fewer bytes than requested. + * The actual number of bytes skipped is returned. This method will not + * skip any bytes if passed a negative number of bytes to skip. + * + * @param numBytes The requested number of bytes to skip. + * + * @return The number of bytes actually skipped. + * + * @exception IOException If an error occurs. + */ + public int skipBytes (int numBytes) throws IOException + { + if (numBytes < 0) + throw new IllegalArgumentException ("Can't skip negative bytes: " + + numBytes); + + if (numBytes == 0) + return 0; + + long oldPos = ch.position(); + long newPos = oldPos + numBytes; + long size = ch.size(); + if (newPos > size) + newPos = size; + ch.position(newPos); + return (int) (ch.position() - oldPos); + } + + /** + * This method writes a single byte of data to the file. The file must + * be open for read-write in order for this operation to succeed. + * + * @param oneByte The byte of data to write, passed as an int. + * + * @exception IOException If an error occurs + */ + public void write (int oneByte) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.write(oneByte); + } + + /** + * This method writes all the bytes in the specified array to the file. + * The file must be open read-write in order for this operation to succeed. + * + * @param buffer The array of bytes to write to the file + */ + public void write (byte[] buffer) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.write(buffer); + } + + /** + * This method writes <code>len</code> bytes to the file from the specified + * array starting at index <code>offset</code> into the array. + * + * @param buffer The array of bytes to write to the file + * @param offset The index into the array to start writing file + * @param len The number of bytes to write + * + * @exception IOException If an error occurs + */ + public void write (byte[] buffer, int offset, int len) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.write (buffer, offset, len); + } + + /** + * This method writes a Java <code>boolean</code> to the underlying output + * stream. For a value of <code>true</code>, 1 is written to the stream. + * For a value of <code>false</code>, 0 is written. + * + * @param val The <code>boolean</code> value to write to the stream + * + * @exception IOException If an error occurs + */ + public final void writeBoolean (boolean val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeBoolean(val); + } + + /** + * This method writes a Java <code>byte</code> value to the underlying + * output stream. + * + * @param val The <code>byte</code> to write to the stream, passed + * as an <code>int</code>. + * + * @exception IOException If an error occurs + */ + public final void writeByte (int val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeByte(val); + } + + /** + * This method writes a Java <code>short</code> to the stream, high byte + * first. This method requires two bytes to encode the value. + * + * @param val The <code>short</code> value to write to the stream, + * passed as an <code>int</code>. + * + * @exception IOException If an error occurs + */ + public final void writeShort (int val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeShort(val); + } + + /** + * This method writes a single <code>char</code> value to the stream, + * high byte first. + * + * @param val The <code>char</code> value to write, passed as + * an <code>int</code>. + * + * @exception IOException If an error occurs + */ + public final void writeChar (int val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeChar(val); + } + + /** + * This method writes a Java <code>int</code> to the stream, high bytes + * first. This method requires four bytes to encode the value. + * + * @param val The <code>int</code> value to write to the stream. + * + * @exception IOException If an error occurs + */ + public final void writeInt (int val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeInt(val); + } + + /** + * This method writes a Java <code>long</code> to the stream, high bytes + * first. This method requires eight bytes to encode the value. + * + * @param val The <code>long</code> value to write to the stream. + * + * @exception IOException If an error occurs + */ + public final void writeLong (long val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeLong(val); + } + + /** + * This method writes a Java <code>float</code> value to the stream. This + * value is written by first calling the method + * <code>Float.floatToIntBits</code> + * to retrieve an <code>int</code> representing the floating point number, + * then writing this <code>int</code> value to the stream exactly the same + * as the <code>writeInt()</code> method does. + * + * @param val The floating point number to write to the stream. + * + * @exception IOException If an error occurs + * + * @see #writeInt(int) + */ + public final void writeFloat (float val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeFloat(val); + } + + /** + * This method writes a Java <code>double</code> value to the stream. This + * value is written by first calling the method + * <code>Double.doubleToLongBits</code> + * to retrieve an <code>long</code> representing the floating point number, + * then writing this <code>long</code> value to the stream exactly the same + * as the <code>writeLong()</code> method does. + * + * @param val The double precision floating point number to write to the + * stream. + * + * @exception IOException If an error occurs + * + * @see #writeLong(long) + */ + public final void writeDouble (double val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeDouble(val); + } + + /** + * This method writes all the bytes in a <code>String</code> out to the + * stream. One byte is written for each character in the <code>String</code>. + * The high eight bits of each character are discarded. + * + * @param val The <code>String</code> to write to the stream + * + * @exception IOException If an error occurs + */ + public final void writeBytes (String val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeBytes(val); + } + + /** + * This method writes all the characters in a <code>String</code> to the + * stream. There will be two bytes for each character value. The high + * byte of the character will be written first. + * + * @param val The <code>String</code> to write to the stream. + * + * @exception IOException If an error occurs + */ + public final void writeChars (String val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeChars(val); + } + + /** + * This method writes a Java <code>String</code> to the stream in a modified + * UTF-8 format. First, two bytes are written to the stream indicating the + * number of bytes to follow. Note that this is the number of bytes in the + * encoded <code>String</code> not the <code>String</code> length. Next + * come the encoded characters. Each character in the <code>String</code> + * is encoded as either one, two or three bytes. For characters in the + * range of <code>\u0001</code> to <code>\u007F</code>, + * one byte is used. The character + * value goes into bits 0-7 and bit eight is 0. For characters in the range + * of <code>\u0080</code> to <code>\u007FF</code>, two + * bytes are used. Bits + * 6-10 of the character value are encoded bits 0-4 of the first byte, with + * the high bytes having a value of "110". Bits 0-5 of the character value + * are stored in bits 0-5 of the second byte, with the high bits set to + * "10". This type of encoding is also done for the null character + * <code>\u0000</code>. This eliminates any C style NUL character values + * in the output. All remaining characters are stored as three bytes. + * Bits 12-15 of the character value are stored in bits 0-3 of the first + * byte. The high bits of the first bytes are set to "1110". Bits 6-11 + * of the character value are stored in bits 0-5 of the second byte. The + * high bits of the second byte are set to "10". And bits 0-5 of the + * character value are stored in bits 0-5 of byte three, with the high bits + * of that byte set to "10". + * + * @param val The <code>String</code> to write to the output in UTF format + * + * @exception IOException If an error occurs + */ + public final void writeUTF (String val) throws IOException + { + if (out == null) + throw new IOException("Bad file descriptor"); + + out.writeUTF(val); + } + + /** + * This method creates a java.nio.channels.FileChannel. + * Nio does not allow one to create a file channel directly. + * A file channel must be created by first creating an instance of + * Input/Output/RandomAccessFile and invoking the getChannel() method on it. + */ + public final synchronized FileChannel getChannel () + { + return ch; + } +} |