0001: /*
0002: * Copyright 1994-2007 Sun Microsystems, Inc. All Rights Reserved.
0003: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
0004: *
0005: * This code is free software; you can redistribute it and/or modify it
0006: * under the terms of the GNU General Public License version 2 only, as
0007: * published by the Free Software Foundation. Sun designates this
0008: * particular file as subject to the "Classpath" exception as provided
0009: * by Sun in the LICENSE file that accompanied this code.
0010: *
0011: * This code is distributed in the hope that it will be useful, but WITHOUT
0012: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
0013: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
0014: * version 2 for more details (a copy is included in the LICENSE file that
0015: * accompanied this code).
0016: *
0017: * You should have received a copy of the GNU General Public License version
0018: * 2 along with this work; if not, write to the Free Software Foundation,
0019: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
0020: *
0021: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
0022: * CA 95054 USA or visit www.sun.com if you need additional information or
0023: * have any questions.
0024: */
0025:
0026: package java.io;
0027:
0028: import java.nio.channels.FileChannel;
0029: import sun.nio.ch.FileChannelImpl;
0030:
0031: /**
0032: * Instances of this class support both reading and writing to a
0033: * random access file. A random access file behaves like a large
0034: * array of bytes stored in the file system. There is a kind of cursor,
0035: * or index into the implied array, called the <em>file pointer</em>;
0036: * input operations read bytes starting at the file pointer and advance
0037: * the file pointer past the bytes read. If the random access file is
0038: * created in read/write mode, then output operations are also available;
0039: * output operations write bytes starting at the file pointer and advance
0040: * the file pointer past the bytes written. Output operations that write
0041: * past the current end of the implied array cause the array to be
0042: * extended. The file pointer can be read by the
0043: * <code>getFilePointer</code> method and set by the <code>seek</code>
0044: * method.
0045: * <p>
0046: * It is generally true of all the reading routines in this class that
0047: * if end-of-file is reached before the desired number of bytes has been
0048: * read, an <code>EOFException</code> (which is a kind of
0049: * <code>IOException</code>) is thrown. If any byte cannot be read for
0050: * any reason other than end-of-file, an <code>IOException</code> other
0051: * than <code>EOFException</code> is thrown. In particular, an
0052: * <code>IOException</code> may be thrown if the stream has been closed.
0053: *
0054: * @author unascribed
0055: * @version 1.90, 06/13/07
0056: * @since JDK1.0
0057: */
0058:
0059: public class RandomAccessFile implements DataOutput, DataInput,
0060: Closeable {
0061:
0062: private FileDescriptor fd;
0063: private FileChannel channel = null;
0064: private boolean rw;
0065:
0066: private Object closeLock = new Object();
0067: private volatile boolean closed = false;
0068:
0069: private static final int O_RDONLY = 1;
0070: private static final int O_RDWR = 2;
0071: private static final int O_SYNC = 4;
0072: private static final int O_DSYNC = 8;
0073:
0074: /**
0075: * Creates a random access file stream to read from, and optionally
0076: * to write to, a file with the specified name. A new
0077: * {@link FileDescriptor} object is created to represent the
0078: * connection to the file.
0079: *
0080: * <p> The <tt>mode</tt> argument specifies the access mode with which the
0081: * file is to be opened. The permitted values and their meanings are as
0082: * specified for the <a
0083: * href="#mode"><tt>RandomAccessFile(File,String)</tt></a> constructor.
0084: *
0085: * <p>
0086: * If there is a security manager, its <code>checkRead</code> method
0087: * is called with the <code>name</code> argument
0088: * as its argument to see if read access to the file is allowed.
0089: * If the mode allows writing, the security manager's
0090: * <code>checkWrite</code> method
0091: * is also called with the <code>name</code> argument
0092: * as its argument to see if write access to the file is allowed.
0093: *
0094: * @param name the system-dependent filename
0095: * @param mode the access <a href="#mode">mode</a>
0096: * @exception IllegalArgumentException if the mode argument is not equal
0097: * to one of <tt>"r"</tt>, <tt>"rw"</tt>, <tt>"rws"</tt>, or
0098: * <tt>"rwd"</tt>
0099: * @exception FileNotFoundException
0100: * if the mode is <tt>"r"</tt> but the given string does not
0101: * denote an existing regular file, or if the mode begins with
0102: * <tt>"rw"</tt> but the given string does not denote an
0103: * existing, writable regular file and a new regular file of
0104: * that name cannot be created, or if some other error occurs
0105: * while opening or creating the file
0106: * @exception SecurityException if a security manager exists and its
0107: * <code>checkRead</code> method denies read access to the file
0108: * or the mode is "rw" and the security manager's
0109: * <code>checkWrite</code> method denies write access to the file
0110: * @see java.lang.SecurityException
0111: * @see java.lang.SecurityManager#checkRead(java.lang.String)
0112: * @see java.lang.SecurityManager#checkWrite(java.lang.String)
0113: * @revised 1.4
0114: * @spec JSR-51
0115: */
0116: public RandomAccessFile(String name, String mode)
0117: throws FileNotFoundException {
0118: this (name != null ? new File(name) : null, mode);
0119: }
0120:
0121: /**
0122: * Creates a random access file stream to read from, and optionally to
0123: * write to, the file specified by the {@link File} argument. A new {@link
0124: * FileDescriptor} object is created to represent this file connection.
0125: *
0126: * <a name="mode"><p> The <tt>mode</tt> argument specifies the access mode
0127: * in which the file is to be opened. The permitted values and their
0128: * meanings are:
0129: *
0130: * <blockquote><table summary="Access mode permitted values and meanings">
0131: * <tr><th><p align="left">Value</p></th><th><p align="left">Meaning</p></th></tr>
0132: * <tr><td valign="top"><tt>"r"</tt></td>
0133: * <td> Open for reading only. Invoking any of the <tt>write</tt>
0134: * methods of the resulting object will cause an {@link
0135: * java.io.IOException} to be thrown. </td></tr>
0136: * <tr><td valign="top"><tt>"rw"</tt></td>
0137: * <td> Open for reading and writing. If the file does not already
0138: * exist then an attempt will be made to create it. </td></tr>
0139: * <tr><td valign="top"><tt>"rws"</tt></td>
0140: * <td> Open for reading and writing, as with <tt>"rw"</tt>, and also
0141: * require that every update to the file's content or metadata be
0142: * written synchronously to the underlying storage device. </td></tr>
0143: * <tr><td valign="top"><tt>"rwd" </tt></td>
0144: * <td> Open for reading and writing, as with <tt>"rw"</tt>, and also
0145: * require that every update to the file's content be written
0146: * synchronously to the underlying storage device. </td></tr>
0147: * </table></blockquote>
0148: *
0149: * The <tt>"rws"</tt> and <tt>"rwd"</tt> modes work much like the {@link
0150: * java.nio.channels.FileChannel#force(boolean) force(boolean)} method of
0151: * the {@link java.nio.channels.FileChannel} class, passing arguments of
0152: * <tt>true</tt> and <tt>false</tt>, respectively, except that they always
0153: * apply to every I/O operation and are therefore often more efficient. If
0154: * the file resides on a local storage device then when an invocation of a
0155: * method of this class returns it is guaranteed that all changes made to
0156: * the file by that invocation will have been written to that device. This
0157: * is useful for ensuring that critical information is not lost in the
0158: * event of a system crash. If the file does not reside on a local device
0159: * then no such guarantee is made.
0160: *
0161: * <p> The <tt>"rwd"</tt> mode can be used to reduce the number of I/O
0162: * operations performed. Using <tt>"rwd"</tt> only requires updates to the
0163: * file's content to be written to storage; using <tt>"rws"</tt> requires
0164: * updates to both the file's content and its metadata to be written, which
0165: * generally requires at least one more low-level I/O operation.
0166: *
0167: * <p> If there is a security manager, its <code>checkRead</code> method is
0168: * called with the pathname of the <code>file</code> argument as its
0169: * argument to see if read access to the file is allowed. If the mode
0170: * allows writing, the security manager's <code>checkWrite</code> method is
0171: * also called with the path argument to see if write access to the file is
0172: * allowed.
0173: *
0174: * @param file the file object
0175: * @param mode the access mode, as described
0176: * <a href="#mode">above</a>
0177: * @exception IllegalArgumentException if the mode argument is not equal
0178: * to one of <tt>"r"</tt>, <tt>"rw"</tt>, <tt>"rws"</tt>, or
0179: * <tt>"rwd"</tt>
0180: * @exception FileNotFoundException
0181: * if the mode is <tt>"r"</tt> but the given file object does
0182: * not denote an existing regular file, or if the mode begins
0183: * with <tt>"rw"</tt> but the given file object does not denote
0184: * an existing, writable regular file and a new regular file of
0185: * that name cannot be created, or if some other error occurs
0186: * while opening or creating the file
0187: * @exception SecurityException if a security manager exists and its
0188: * <code>checkRead</code> method denies read access to the file
0189: * or the mode is "rw" and the security manager's
0190: * <code>checkWrite</code> method denies write access to the file
0191: * @see java.lang.SecurityManager#checkRead(java.lang.String)
0192: * @see java.lang.SecurityManager#checkWrite(java.lang.String)
0193: * @see java.nio.channels.FileChannel#force(boolean)
0194: * @revised 1.4
0195: * @spec JSR-51
0196: */
0197: public RandomAccessFile(File file, String mode)
0198: throws FileNotFoundException {
0199: String name = (file != null ? file.getPath() : null);
0200: int imode = -1;
0201: if (mode.equals("r"))
0202: imode = O_RDONLY;
0203: else if (mode.startsWith("rw")) {
0204: imode = O_RDWR;
0205: rw = true;
0206: if (mode.length() > 2) {
0207: if (mode.equals("rws"))
0208: imode |= O_SYNC;
0209: else if (mode.equals("rwd"))
0210: imode |= O_DSYNC;
0211: else
0212: imode = -1;
0213: }
0214: }
0215: if (imode < 0)
0216: throw new IllegalArgumentException("Illegal mode \"" + mode
0217: + "\" must be one of " + "\"r\", \"rw\", \"rws\","
0218: + " or \"rwd\"");
0219: SecurityManager security = System.getSecurityManager();
0220: if (security != null) {
0221: security.checkRead(name);
0222: if (rw) {
0223: security.checkWrite(name);
0224: }
0225: }
0226: if (name == null) {
0227: throw new NullPointerException();
0228: }
0229: fd = new FileDescriptor();
0230: fd.incrementAndGetUseCount();
0231: open(name, imode);
0232: }
0233:
0234: /**
0235: * Returns the opaque file descriptor object associated with this
0236: * stream. </p>
0237: *
0238: * @return the file descriptor object associated with this stream.
0239: * @exception IOException if an I/O error occurs.
0240: * @see java.io.FileDescriptor
0241: */
0242: public final FileDescriptor getFD() throws IOException {
0243: if (fd != null)
0244: return fd;
0245: throw new IOException();
0246: }
0247:
0248: /**
0249: * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
0250: * object associated with this file.
0251: *
0252: * <p> The {@link java.nio.channels.FileChannel#position()
0253: * </code>position<code>} of the returned channel will always be equal to
0254: * this object's file-pointer offset as returned by the {@link
0255: * #getFilePointer getFilePointer} method. Changing this object's
0256: * file-pointer offset, whether explicitly or by reading or writing bytes,
0257: * will change the position of the channel, and vice versa. Changing the
0258: * file's length via this object will change the length seen via the file
0259: * channel, and vice versa.
0260: *
0261: * @return the file channel associated with this file
0262: *
0263: * @since 1.4
0264: * @spec JSR-51
0265: */
0266: public final FileChannel getChannel() {
0267: synchronized (this ) {
0268: if (channel == null) {
0269: channel = FileChannelImpl.open(fd, true, rw, this );
0270:
0271: /*
0272: * FileDescriptor could be shared by FileInputStream or
0273: * FileOutputStream.
0274: * Ensure that FD is GC'ed only when all the streams/channels
0275: * are done using it.
0276: * Increment fd's use count. Invoking the channel's close()
0277: * method will result in decrementing the use count set for
0278: * the channel.
0279: */
0280: fd.incrementAndGetUseCount();
0281: }
0282: return channel;
0283: }
0284: }
0285:
0286: /**
0287: * Opens a file and returns the file descriptor. The file is
0288: * opened in read-write mode if the O_RDWR bit in <code>mode</code>
0289: * is true, else the file is opened as read-only.
0290: * If the <code>name</code> refers to a directory, an IOException
0291: * is thrown.
0292: *
0293: * @param name the name of the file
0294: * @param mode the mode flags, a combination of the O_ constants
0295: * defined above
0296: */
0297: private native void open(String name, int mode)
0298: throws FileNotFoundException;
0299:
0300: // 'Read' primitives
0301:
0302: /**
0303: * Reads a byte of data from this file. The byte is returned as an
0304: * integer in the range 0 to 255 (<code>0x00-0x0ff</code>). This
0305: * method blocks if no input is yet available.
0306: * <p>
0307: * Although <code>RandomAccessFile</code> is not a subclass of
0308: * <code>InputStream</code>, this method behaves in exactly the same
0309: * way as the {@link InputStream#read()} method of
0310: * <code>InputStream</code>.
0311: *
0312: * @return the next byte of data, or <code>-1</code> if the end of the
0313: * file has been reached.
0314: * @exception IOException if an I/O error occurs. Not thrown if
0315: * end-of-file has been reached.
0316: */
0317: public native int read() throws IOException;
0318:
0319: /**
0320: * Reads a sub array as a sequence of bytes.
0321: * @param b the buffer into which the data is read.
0322: * @param off the start offset of the data.
0323: * @param len the number of bytes to read.
0324: * @exception IOException If an I/O error has occurred.
0325: */
0326: private native int readBytes(byte b[], int off, int len)
0327: throws IOException;
0328:
0329: /**
0330: * Reads up to <code>len</code> bytes of data from this file into an
0331: * array of bytes. This method blocks until at least one byte of input
0332: * is available.
0333: * <p>
0334: * Although <code>RandomAccessFile</code> is not a subclass of
0335: * <code>InputStream</code>, this method behaves in exactly the
0336: * same way as the {@link InputStream#read(byte[], int, int)} method of
0337: * <code>InputStream</code>.
0338: *
0339: * @param b the buffer into which the data is read.
0340: * @param off the start offset in array <code>b</code>
0341: * at which the data is written.
0342: * @param len the maximum number of bytes read.
0343: * @return the total number of bytes read into the buffer, or
0344: * <code>-1</code> if there is no more data because the end of
0345: * the file has been reached.
0346: * @exception IOException If the first byte cannot be read for any reason
0347: * other than end of file, or if the random access file has been closed, or if
0348: * some other I/O error occurs.
0349: * @exception NullPointerException If <code>b</code> is <code>null</code>.
0350: * @exception IndexOutOfBoundsException If <code>off</code> is negative,
0351: * <code>len</code> is negative, or <code>len</code> is greater than
0352: * <code>b.length - off</code>
0353: */
0354: public int read(byte b[], int off, int len) throws IOException {
0355: return readBytes(b, off, len);
0356: }
0357:
0358: /**
0359: * Reads up to <code>b.length</code> bytes of data from this file
0360: * into an array of bytes. This method blocks until at least one byte
0361: * of input is available.
0362: * <p>
0363: * Although <code>RandomAccessFile</code> is not a subclass of
0364: * <code>InputStream</code>, this method behaves in exactly the
0365: * same way as the {@link InputStream#read(byte[])} method of
0366: * <code>InputStream</code>.
0367: *
0368: * @param b the buffer into which the data is read.
0369: * @return the total number of bytes read into the buffer, or
0370: * <code>-1</code> if there is no more data because the end of
0371: * this file has been reached.
0372: * @exception IOException If the first byte cannot be read for any reason
0373: * other than end of file, or if the random access file has been closed, or if
0374: * some other I/O error occurs.
0375: * @exception NullPointerException If <code>b</code> is <code>null</code>.
0376: */
0377: public int read(byte b[]) throws IOException {
0378: return readBytes(b, 0, b.length);
0379: }
0380:
0381: /**
0382: * Reads <code>b.length</code> bytes from this file into the byte
0383: * array, starting at the current file pointer. This method reads
0384: * repeatedly from the file until the requested number of bytes are
0385: * read. This method blocks until the requested number of bytes are
0386: * read, the end of the stream is detected, or an exception is thrown.
0387: *
0388: * @param b the buffer into which the data is read.
0389: * @exception EOFException if this file reaches the end before reading
0390: * all the bytes.
0391: * @exception IOException if an I/O error occurs.
0392: */
0393: public final void readFully(byte b[]) throws IOException {
0394: readFully(b, 0, b.length);
0395: }
0396:
0397: /**
0398: * Reads exactly <code>len</code> bytes from this file into the byte
0399: * array, starting at the current file pointer. This method reads
0400: * repeatedly from the file until the requested number of bytes are
0401: * read. This method blocks until the requested number of bytes are
0402: * read, the end of the stream is detected, or an exception is thrown.
0403: *
0404: * @param b the buffer into which the data is read.
0405: * @param off the start offset of the data.
0406: * @param len the number of bytes to read.
0407: * @exception EOFException if this file reaches the end before reading
0408: * all the bytes.
0409: * @exception IOException if an I/O error occurs.
0410: */
0411: public final void readFully(byte b[], int off, int len)
0412: throws IOException {
0413: int n = 0;
0414: do {
0415: int count = this .read(b, off + n, len - n);
0416: if (count < 0)
0417: throw new EOFException();
0418: n += count;
0419: } while (n < len);
0420: }
0421:
0422: /**
0423: * Attempts to skip over <code>n</code> bytes of input discarding the
0424: * skipped bytes.
0425: * <p>
0426: *
0427: * This method may skip over some smaller number of bytes, possibly zero.
0428: * This may result from any of a number of conditions; reaching end of
0429: * file before <code>n</code> bytes have been skipped is only one
0430: * possibility. This method never throws an <code>EOFException</code>.
0431: * The actual number of bytes skipped is returned. If <code>n</code>
0432: * is negative, no bytes are skipped.
0433: *
0434: * @param n the number of bytes to be skipped.
0435: * @return the actual number of bytes skipped.
0436: * @exception IOException if an I/O error occurs.
0437: */
0438: public int skipBytes(int n) throws IOException {
0439: long pos;
0440: long len;
0441: long newpos;
0442:
0443: if (n <= 0) {
0444: return 0;
0445: }
0446: pos = getFilePointer();
0447: len = length();
0448: newpos = pos + n;
0449: if (newpos > len) {
0450: newpos = len;
0451: }
0452: seek(newpos);
0453:
0454: /* return the actual number of bytes skipped */
0455: return (int) (newpos - pos);
0456: }
0457:
0458: // 'Write' primitives
0459:
0460: /**
0461: * Writes the specified byte to this file. The write starts at
0462: * the current file pointer.
0463: *
0464: * @param b the <code>byte</code> to be written.
0465: * @exception IOException if an I/O error occurs.
0466: */
0467: public native void write(int b) throws IOException;
0468:
0469: /**
0470: * Writes a sub array as a sequence of bytes.
0471: * @param b the data to be written
0472:
0473: * @param off the start offset in the data
0474: * @param len the number of bytes that are written
0475: * @exception IOException If an I/O error has occurred.
0476: */
0477: private native void writeBytes(byte b[], int off, int len)
0478: throws IOException;
0479:
0480: /**
0481: * Writes <code>b.length</code> bytes from the specified byte array
0482: * to this file, starting at the current file pointer.
0483: *
0484: * @param b the data.
0485: * @exception IOException if an I/O error occurs.
0486: */
0487: public void write(byte b[]) throws IOException {
0488: writeBytes(b, 0, b.length);
0489: }
0490:
0491: /**
0492: * Writes <code>len</code> bytes from the specified byte array
0493: * starting at offset <code>off</code> to this file.
0494: *
0495: * @param b the data.
0496: * @param off the start offset in the data.
0497: * @param len the number of bytes to write.
0498: * @exception IOException if an I/O error occurs.
0499: */
0500: public void write(byte b[], int off, int len) throws IOException {
0501: writeBytes(b, off, len);
0502: }
0503:
0504: // 'Random access' stuff
0505:
0506: /**
0507: * Returns the current offset in this file.
0508: *
0509: * @return the offset from the beginning of the file, in bytes,
0510: * at which the next read or write occurs.
0511: * @exception IOException if an I/O error occurs.
0512: */
0513: public native long getFilePointer() throws IOException;
0514:
0515: /**
0516: * Sets the file-pointer offset, measured from the beginning of this
0517: * file, at which the next read or write occurs. The offset may be
0518: * set beyond the end of the file. Setting the offset beyond the end
0519: * of the file does not change the file length. The file length will
0520: * change only by writing after the offset has been set beyond the end
0521: * of the file.
0522: *
0523: * @param pos the offset position, measured in bytes from the
0524: * beginning of the file, at which to set the file
0525: * pointer.
0526: * @exception IOException if <code>pos</code> is less than
0527: * <code>0</code> or if an I/O error occurs.
0528: */
0529: public native void seek(long pos) throws IOException;
0530:
0531: /**
0532: * Returns the length of this file.
0533: *
0534: * @return the length of this file, measured in bytes.
0535: * @exception IOException if an I/O error occurs.
0536: */
0537: public native long length() throws IOException;
0538:
0539: /**
0540: * Sets the length of this file.
0541: *
0542: * <p> If the present length of the file as returned by the
0543: * <code>length</code> method is greater than the <code>newLength</code>
0544: * argument then the file will be truncated. In this case, if the file
0545: * offset as returned by the <code>getFilePointer</code> method is greater
0546: * than <code>newLength</code> then after this method returns the offset
0547: * will be equal to <code>newLength</code>.
0548: *
0549: * <p> If the present length of the file as returned by the
0550: * <code>length</code> method is smaller than the <code>newLength</code>
0551: * argument then the file will be extended. In this case, the contents of
0552: * the extended portion of the file are not defined.
0553: *
0554: * @param newLength The desired length of the file
0555: * @exception IOException If an I/O error occurs
0556: * @since 1.2
0557: */
0558: public native void setLength(long newLength) throws IOException;
0559:
0560: /**
0561: * Closes this random access file stream and releases any system
0562: * resources associated with the stream. A closed random access
0563: * file cannot perform input or output operations and cannot be
0564: * reopened.
0565: *
0566: * <p> If this file has an associated channel then the channel is closed
0567: * as well.
0568: *
0569: * @exception IOException if an I/O error occurs.
0570: *
0571: * @revised 1.4
0572: * @spec JSR-51
0573: */
0574: public void close() throws IOException {
0575: synchronized (closeLock) {
0576: if (closed) {
0577: return;
0578: }
0579: closed = true;
0580: }
0581: if (channel != null) {
0582: /*
0583: * Decrement FD use count associated with the channel. The FD use
0584: * count is incremented whenever a new channel is obtained from
0585: * this stream.
0586: */
0587: fd.decrementAndGetUseCount();
0588: channel.close();
0589: }
0590:
0591: /*
0592: * Decrement FD use count associated with this stream.
0593: * The count got incremented by FileDescriptor during its construction.
0594: */
0595: fd.decrementAndGetUseCount();
0596: close0();
0597: }
0598:
0599: //
0600: // Some "reading/writing Java data types" methods stolen from
0601: // DataInputStream and DataOutputStream.
0602: //
0603:
0604: /**
0605: * Reads a <code>boolean</code> from this file. This method reads a
0606: * single byte from the file, starting at the current file pointer.
0607: * A value of <code>0</code> represents
0608: * <code>false</code>. Any other value represents <code>true</code>.
0609: * This method blocks until the byte is read, the end of the stream
0610: * is detected, or an exception is thrown.
0611: *
0612: * @return the <code>boolean</code> value read.
0613: * @exception EOFException if this file has reached the end.
0614: * @exception IOException if an I/O error occurs.
0615: */
0616: public final boolean readBoolean() throws IOException {
0617: int ch = this .read();
0618: if (ch < 0)
0619: throw new EOFException();
0620: return (ch != 0);
0621: }
0622:
0623: /**
0624: * Reads a signed eight-bit value from this file. This method reads a
0625: * byte from the file, starting from the current file pointer.
0626: * If the byte read is <code>b</code>, where
0627: * <code>0 <= b <= 255</code>,
0628: * then the result is:
0629: * <blockquote><pre>
0630: * (byte)(b)
0631: * </pre></blockquote>
0632: * <p>
0633: * This method blocks until the byte is read, the end of the stream
0634: * is detected, or an exception is thrown.
0635: *
0636: * @return the next byte of this file as a signed eight-bit
0637: * <code>byte</code>.
0638: * @exception EOFException if this file has reached the end.
0639: * @exception IOException if an I/O error occurs.
0640: */
0641: public final byte readByte() throws IOException {
0642: int ch = this .read();
0643: if (ch < 0)
0644: throw new EOFException();
0645: return (byte) (ch);
0646: }
0647:
0648: /**
0649: * Reads an unsigned eight-bit number from this file. This method reads
0650: * a byte from this file, starting at the current file pointer,
0651: * and returns that byte.
0652: * <p>
0653: * This method blocks until the byte is read, the end of the stream
0654: * is detected, or an exception is thrown.
0655: *
0656: * @return the next byte of this file, interpreted as an unsigned
0657: * eight-bit number.
0658: * @exception EOFException if this file has reached the end.
0659: * @exception IOException if an I/O error occurs.
0660: */
0661: public final int readUnsignedByte() throws IOException {
0662: int ch = this .read();
0663: if (ch < 0)
0664: throw new EOFException();
0665: return ch;
0666: }
0667:
0668: /**
0669: * Reads a signed 16-bit number from this file. The method reads two
0670: * bytes from this file, starting at the current file pointer.
0671: * If the two bytes read, in order, are
0672: * <code>b1</code> and <code>b2</code>, where each of the two values is
0673: * between <code>0</code> and <code>255</code>, inclusive, then the
0674: * result is equal to:
0675: * <blockquote><pre>
0676: * (short)((b1 << 8) | b2)
0677: * </pre></blockquote>
0678: * <p>
0679: * This method blocks until the two bytes are read, the end of the
0680: * stream is detected, or an exception is thrown.
0681: *
0682: * @return the next two bytes of this file, interpreted as a signed
0683: * 16-bit number.
0684: * @exception EOFException if this file reaches the end before reading
0685: * two bytes.
0686: * @exception IOException if an I/O error occurs.
0687: */
0688: public final short readShort() throws IOException {
0689: int ch1 = this .read();
0690: int ch2 = this .read();
0691: if ((ch1 | ch2) < 0)
0692: throw new EOFException();
0693: return (short) ((ch1 << 8) + (ch2 << 0));
0694: }
0695:
0696: /**
0697: * Reads an unsigned 16-bit number from this file. This method reads
0698: * two bytes from the file, starting at the current file pointer.
0699: * If the bytes read, in order, are
0700: * <code>b1</code> and <code>b2</code>, where
0701: * <code>0 <= b1, b2 <= 255</code>,
0702: * then the result is equal to:
0703: * <blockquote><pre>
0704: * (b1 << 8) | b2
0705: * </pre></blockquote>
0706: * <p>
0707: * This method blocks until the two bytes are read, the end of the
0708: * stream is detected, or an exception is thrown.
0709: *
0710: * @return the next two bytes of this file, interpreted as an unsigned
0711: * 16-bit integer.
0712: * @exception EOFException if this file reaches the end before reading
0713: * two bytes.
0714: * @exception IOException if an I/O error occurs.
0715: */
0716: public final int readUnsignedShort() throws IOException {
0717: int ch1 = this .read();
0718: int ch2 = this .read();
0719: if ((ch1 | ch2) < 0)
0720: throw new EOFException();
0721: return (ch1 << 8) + (ch2 << 0);
0722: }
0723:
0724: /**
0725: * Reads a character from this file. This method reads two
0726: * bytes from the file, starting at the current file pointer.
0727: * If the bytes read, in order, are
0728: * <code>b1</code> and <code>b2</code>, where
0729: * <code>0 <= b1, b2 <= 255</code>,
0730: * then the result is equal to:
0731: * <blockquote><pre>
0732: * (char)((b1 << 8) | b2)
0733: * </pre></blockquote>
0734: * <p>
0735: * This method blocks until the two bytes are read, the end of the
0736: * stream is detected, or an exception is thrown.
0737: *
0738: * @return the next two bytes of this file, interpreted as a
0739: * <code>char</code>.
0740: * @exception EOFException if this file reaches the end before reading
0741: * two bytes.
0742: * @exception IOException if an I/O error occurs.
0743: */
0744: public final char readChar() throws IOException {
0745: int ch1 = this .read();
0746: int ch2 = this .read();
0747: if ((ch1 | ch2) < 0)
0748: throw new EOFException();
0749: return (char) ((ch1 << 8) + (ch2 << 0));
0750: }
0751:
0752: /**
0753: * Reads a signed 32-bit integer from this file. This method reads 4
0754: * bytes from the file, starting at the current file pointer.
0755: * If the bytes read, in order, are <code>b1</code>,
0756: * <code>b2</code>, <code>b3</code>, and <code>b4</code>, where
0757: * <code>0 <= b1, b2, b3, b4 <= 255</code>,
0758: * then the result is equal to:
0759: * <blockquote><pre>
0760: * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4
0761: * </pre></blockquote>
0762: * <p>
0763: * This method blocks until the four bytes are read, the end of the
0764: * stream is detected, or an exception is thrown.
0765: *
0766: * @return the next four bytes of this file, interpreted as an
0767: * <code>int</code>.
0768: * @exception EOFException if this file reaches the end before reading
0769: * four bytes.
0770: * @exception IOException if an I/O error occurs.
0771: */
0772: public final int readInt() throws IOException {
0773: int ch1 = this .read();
0774: int ch2 = this .read();
0775: int ch3 = this .read();
0776: int ch4 = this .read();
0777: if ((ch1 | ch2 | ch3 | ch4) < 0)
0778: throw new EOFException();
0779: return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
0780: }
0781:
0782: /**
0783: * Reads a signed 64-bit integer from this file. This method reads eight
0784: * bytes from the file, starting at the current file pointer.
0785: * If the bytes read, in order, are
0786: * <code>b1</code>, <code>b2</code>, <code>b3</code>,
0787: * <code>b4</code>, <code>b5</code>, <code>b6</code>,
0788: * <code>b7</code>, and <code>b8,</code> where:
0789: * <blockquote><pre>
0790: * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
0791: * </pre></blockquote>
0792: * <p>
0793: * then the result is equal to:
0794: * <p><blockquote><pre>
0795: * ((long)b1 << 56) + ((long)b2 << 48)
0796: * + ((long)b3 << 40) + ((long)b4 << 32)
0797: * + ((long)b5 << 24) + ((long)b6 << 16)
0798: * + ((long)b7 << 8) + b8
0799: * </pre></blockquote>
0800: * <p>
0801: * This method blocks until the eight bytes are read, the end of the
0802: * stream is detected, or an exception is thrown.
0803: *
0804: * @return the next eight bytes of this file, interpreted as a
0805: * <code>long</code>.
0806: * @exception EOFException if this file reaches the end before reading
0807: * eight bytes.
0808: * @exception IOException if an I/O error occurs.
0809: */
0810: public final long readLong() throws IOException {
0811: return ((long) (readInt()) << 32) + (readInt() & 0xFFFFFFFFL);
0812: }
0813:
0814: /**
0815: * Reads a <code>float</code> from this file. This method reads an
0816: * <code>int</code> value, starting at the current file pointer,
0817: * as if by the <code>readInt</code> method
0818: * and then converts that <code>int</code> to a <code>float</code>
0819: * using the <code>intBitsToFloat</code> method in class
0820: * <code>Float</code>.
0821: * <p>
0822: * This method blocks until the four bytes are read, the end of the
0823: * stream is detected, or an exception is thrown.
0824: *
0825: * @return the next four bytes of this file, interpreted as a
0826: * <code>float</code>.
0827: * @exception EOFException if this file reaches the end before reading
0828: * four bytes.
0829: * @exception IOException if an I/O error occurs.
0830: * @see java.io.RandomAccessFile#readInt()
0831: * @see java.lang.Float#intBitsToFloat(int)
0832: */
0833: public final float readFloat() throws IOException {
0834: return Float.intBitsToFloat(readInt());
0835: }
0836:
0837: /**
0838: * Reads a <code>double</code> from this file. This method reads a
0839: * <code>long</code> value, starting at the current file pointer,
0840: * as if by the <code>readLong</code> method
0841: * and then converts that <code>long</code> to a <code>double</code>
0842: * using the <code>longBitsToDouble</code> method in
0843: * class <code>Double</code>.
0844: * <p>
0845: * This method blocks until the eight bytes are read, the end of the
0846: * stream is detected, or an exception is thrown.
0847: *
0848: * @return the next eight bytes of this file, interpreted as a
0849: * <code>double</code>.
0850: * @exception EOFException if this file reaches the end before reading
0851: * eight bytes.
0852: * @exception IOException if an I/O error occurs.
0853: * @see java.io.RandomAccessFile#readLong()
0854: * @see java.lang.Double#longBitsToDouble(long)
0855: */
0856: public final double readDouble() throws IOException {
0857: return Double.longBitsToDouble(readLong());
0858: }
0859:
0860: /**
0861: * Reads the next line of text from this file. This method successively
0862: * reads bytes from the file, starting at the current file pointer,
0863: * until it reaches a line terminator or the end
0864: * of the file. Each byte is converted into a character by taking the
0865: * byte's value for the lower eight bits of the character and setting the
0866: * high eight bits of the character to zero. This method does not,
0867: * therefore, support the full Unicode character set.
0868: *
0869: * <p> A line of text is terminated by a carriage-return character
0870: * (<code>'\r'</code>), a newline character (<code>'\n'</code>), a
0871: * carriage-return character immediately followed by a newline character,
0872: * or the end of the file. Line-terminating characters are discarded and
0873: * are not included as part of the string returned.
0874: *
0875: * <p> This method blocks until a newline character is read, a carriage
0876: * return and the byte following it are read (to see if it is a newline),
0877: * the end of the file is reached, or an exception is thrown.
0878: *
0879: * @return the next line of text from this file, or null if end
0880: * of file is encountered before even one byte is read.
0881: * @exception IOException if an I/O error occurs.
0882: */
0883:
0884: public final String readLine() throws IOException {
0885: StringBuffer input = new StringBuffer();
0886: int c = -1;
0887: boolean eol = false;
0888:
0889: while (!eol) {
0890: switch (c = read()) {
0891: case -1:
0892: case '\n':
0893: eol = true;
0894: break;
0895: case '\r':
0896: eol = true;
0897: long cur = getFilePointer();
0898: if ((read()) != '\n') {
0899: seek(cur);
0900: }
0901: break;
0902: default:
0903: input.append((char) c);
0904: break;
0905: }
0906: }
0907:
0908: if ((c == -1) && (input.length() == 0)) {
0909: return null;
0910: }
0911: return input.toString();
0912: }
0913:
0914: /**
0915: * Reads in a string from this file. The string has been encoded
0916: * using a
0917: * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
0918: * format.
0919: * <p>
0920: * The first two bytes are read, starting from the current file
0921: * pointer, as if by
0922: * <code>readUnsignedShort</code>. This value gives the number of
0923: * following bytes that are in the encoded string, not
0924: * the length of the resulting string. The following bytes are then
0925: * interpreted as bytes encoding characters in the modified UTF-8 format
0926: * and are converted into characters.
0927: * <p>
0928: * This method blocks until all the bytes are read, the end of the
0929: * stream is detected, or an exception is thrown.
0930: *
0931: * @return a Unicode string.
0932: * @exception EOFException if this file reaches the end before
0933: * reading all the bytes.
0934: * @exception IOException if an I/O error occurs.
0935: * @exception UTFDataFormatException if the bytes do not represent
0936: * valid modified UTF-8 encoding of a Unicode string.
0937: * @see java.io.RandomAccessFile#readUnsignedShort()
0938: */
0939: public final String readUTF() throws IOException {
0940: return DataInputStream.readUTF(this );
0941: }
0942:
0943: /**
0944: * Writes a <code>boolean</code> to the file as a one-byte value. The
0945: * value <code>true</code> is written out as the value
0946: * <code>(byte)1</code>; the value <code>false</code> is written out
0947: * as the value <code>(byte)0</code>. The write starts at
0948: * the current position of the file pointer.
0949: *
0950: * @param v a <code>boolean</code> value to be written.
0951: * @exception IOException if an I/O error occurs.
0952: */
0953: public final void writeBoolean(boolean v) throws IOException {
0954: write(v ? 1 : 0);
0955: //written++;
0956: }
0957:
0958: /**
0959: * Writes a <code>byte</code> to the file as a one-byte value. The
0960: * write starts at the current position of the file pointer.
0961: *
0962: * @param v a <code>byte</code> value to be written.
0963: * @exception IOException if an I/O error occurs.
0964: */
0965: public final void writeByte(int v) throws IOException {
0966: write(v);
0967: //written++;
0968: }
0969:
0970: /**
0971: * Writes a <code>short</code> to the file as two bytes, high byte first.
0972: * The write starts at the current position of the file pointer.
0973: *
0974: * @param v a <code>short</code> to be written.
0975: * @exception IOException if an I/O error occurs.
0976: */
0977: public final void writeShort(int v) throws IOException {
0978: write((v >>> 8) & 0xFF);
0979: write((v >>> 0) & 0xFF);
0980: //written += 2;
0981: }
0982:
0983: /**
0984: * Writes a <code>char</code> to the file as a two-byte value, high
0985: * byte first. The write starts at the current position of the
0986: * file pointer.
0987: *
0988: * @param v a <code>char</code> value to be written.
0989: * @exception IOException if an I/O error occurs.
0990: */
0991: public final void writeChar(int v) throws IOException {
0992: write((v >>> 8) & 0xFF);
0993: write((v >>> 0) & 0xFF);
0994: //written += 2;
0995: }
0996:
0997: /**
0998: * Writes an <code>int</code> to the file as four bytes, high byte first.
0999: * The write starts at the current position of the file pointer.
1000: *
1001: * @param v an <code>int</code> to be written.
1002: * @exception IOException if an I/O error occurs.
1003: */
1004: public final void writeInt(int v) throws IOException {
1005: write((v >>> 24) & 0xFF);
1006: write((v >>> 16) & 0xFF);
1007: write((v >>> 8) & 0xFF);
1008: write((v >>> 0) & 0xFF);
1009: //written += 4;
1010: }
1011:
1012: /**
1013: * Writes a <code>long</code> to the file as eight bytes, high byte first.
1014: * The write starts at the current position of the file pointer.
1015: *
1016: * @param v a <code>long</code> to be written.
1017: * @exception IOException if an I/O error occurs.
1018: */
1019: public final void writeLong(long v) throws IOException {
1020: write((int) (v >>> 56) & 0xFF);
1021: write((int) (v >>> 48) & 0xFF);
1022: write((int) (v >>> 40) & 0xFF);
1023: write((int) (v >>> 32) & 0xFF);
1024: write((int) (v >>> 24) & 0xFF);
1025: write((int) (v >>> 16) & 0xFF);
1026: write((int) (v >>> 8) & 0xFF);
1027: write((int) (v >>> 0) & 0xFF);
1028: //written += 8;
1029: }
1030:
1031: /**
1032: * Converts the float argument to an <code>int</code> using the
1033: * <code>floatToIntBits</code> method in class <code>Float</code>,
1034: * and then writes that <code>int</code> value to the file as a
1035: * four-byte quantity, high byte first. The write starts at the
1036: * current position of the file pointer.
1037: *
1038: * @param v a <code>float</code> value to be written.
1039: * @exception IOException if an I/O error occurs.
1040: * @see java.lang.Float#floatToIntBits(float)
1041: */
1042: public final void writeFloat(float v) throws IOException {
1043: writeInt(Float.floatToIntBits(v));
1044: }
1045:
1046: /**
1047: * Converts the double argument to a <code>long</code> using the
1048: * <code>doubleToLongBits</code> method in class <code>Double</code>,
1049: * and then writes that <code>long</code> value to the file as an
1050: * eight-byte quantity, high byte first. The write starts at the current
1051: * position of the file pointer.
1052: *
1053: * @param v a <code>double</code> value to be written.
1054: * @exception IOException if an I/O error occurs.
1055: * @see java.lang.Double#doubleToLongBits(double)
1056: */
1057: public final void writeDouble(double v) throws IOException {
1058: writeLong(Double.doubleToLongBits(v));
1059: }
1060:
1061: /**
1062: * Writes the string to the file as a sequence of bytes. Each
1063: * character in the string is written out, in sequence, by discarding
1064: * its high eight bits. The write starts at the current position of
1065: * the file pointer.
1066: *
1067: * @param s a string of bytes to be written.
1068: * @exception IOException if an I/O error occurs.
1069: */
1070: public final void writeBytes(String s) throws IOException {
1071: int len = s.length();
1072: byte[] b = new byte[len];
1073: s.getBytes(0, len, b, 0);
1074: writeBytes(b, 0, len);
1075: }
1076:
1077: /**
1078: * Writes a string to the file as a sequence of characters. Each
1079: * character is written to the data output stream as if by the
1080: * <code>writeChar</code> method. The write starts at the current
1081: * position of the file pointer.
1082: *
1083: * @param s a <code>String</code> value to be written.
1084: * @exception IOException if an I/O error occurs.
1085: * @see java.io.RandomAccessFile#writeChar(int)
1086: */
1087: public final void writeChars(String s) throws IOException {
1088: int clen = s.length();
1089: int blen = 2 * clen;
1090: byte[] b = new byte[blen];
1091: char[] c = new char[clen];
1092: s.getChars(0, clen, c, 0);
1093: for (int i = 0, j = 0; i < clen; i++) {
1094: b[j++] = (byte) (c[i] >>> 8);
1095: b[j++] = (byte) (c[i] >>> 0);
1096: }
1097: writeBytes(b, 0, blen);
1098: }
1099:
1100: /**
1101: * Writes a string to the file using
1102: * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
1103: * encoding in a machine-independent manner.
1104: * <p>
1105: * First, two bytes are written to the file, starting at the
1106: * current file pointer, as if by the
1107: * <code>writeShort</code> method giving the number of bytes to
1108: * follow. This value is the number of bytes actually written out,
1109: * not the length of the string. Following the length, each character
1110: * of the string is output, in sequence, using the modified UTF-8 encoding
1111: * for each character.
1112: *
1113: * @param str a string to be written.
1114: * @exception IOException if an I/O error occurs.
1115: */
1116: public final void writeUTF(String str) throws IOException {
1117: DataOutputStream.writeUTF(str, this );
1118: }
1119:
1120: private static native void initIDs();
1121:
1122: private native void close0() throws IOException;
1123:
1124: static {
1125: initIDs();
1126: }
1127: }
|
