Chip: Shareware for Win 95/Chip-Shareware-Win95.bin/ostatni/powerj/java.z/SocketInputStream.java

Java Source | 1996-05-03 | 4.4 KB | 156 lines

/*
 * @(#)SocketInputStream.java    1.12 96/03/24 Jonathan Payne
 *
 * Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies. Please refer to the file "copyright.html"
 * for further important copyright and licensing information.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */

package java.net;

import java.io.IOException;
import java.io.FileInputStream;

/**
 * This stream extends FileInputStream to implement a
 * SocketInputStream. Note that this class should <b>NOT</b> be
 * public.
 *
 * @version     1.12, 24 Mar 1996
 * @author    Jonathan Payne
 * @author    Arthur van Hoff
 */
class SocketInputStream extends FileInputStream
{
    private boolean eof;
    private SocketImpl impl;
    private byte temp[] = new byte[1];

    /**
     * Creates a new SocketInputStream. Can only be called
     * by a Socket. This method needs to hang on to the owner Socket so
     * that the fd will not be closed.
     * @param impl the implemented socket input stream
     */
    SocketInputStream(SocketImpl impl) throws IOException {
    super(impl.getFileDescriptor());
    this.impl = impl;
    }

    /**
     * Reads into an array of bytes at the specified offset using
     * the received socket primitive.
     * @param b the buffer into which the data is read
     * @param off the start offset of the data
     * @param len the maximum number of bytes read
     * @return the actual number of bytes read, -1 is
     *          returned when the end of the stream is reached.
     * @exception IOException If an I/O error has occurred.
     */
    private native int socketRead(byte b[], int off, int len)
    throws IOException;

    /**
     * Reads into a byte array data from the socket.
     * @param b the buffer into which the data is read
     * @return the actual number of bytes read, -1 is
     *          returned when the end of the stream is reached.
     * @exception IOException If an I/O error has occurred.
     */
    public int read(byte b[]) throws IOException {
    return read(b, 0, b.length);
    }

    /**
     * Reads into a byte array <i>b</i> at offset <i>off</i>,
     * <i>length</i> bytes of data.
     * @param b the buffer into which the data is read
     * @param off the start offset of the data
     * @param len the maximum number of bytes read
     * @return the actual number of bytes read, -1 is
     *          returned when the end of the stream is reached.
     * @exception IOException If an I/O error has occurred.
     */
    public int read(byte b[], int off, int length) throws IOException {
    if (eof) {
        return -1;
    }
    int n = socketRead(b, off, length);
    if (n <= 0) {
        eof = true;
        return -1;
    }
    return n;
    }

    /**
     * Reads a single byte from the socket.
     */
    public int read() throws IOException {
    if (eof) {
        return -1;
    }

     int n = read(temp, 0, 1);
    if (n <= 0) {
        return -1;
    }
    return temp[0] & 0xff;
    }

    /**
     * Skips n bytes of input.
     * @param n the number of bytes to skip
     * @return    the actual number of bytes skipped.
     * @exception IOException If an I/O error has occurred.
     */
    public long skip(long numbytes) throws IOException {
    if (numbytes <= 0) {
        return numbytes;
    }
    long n = numbytes;
    int buflen = (int) Math.min(1024, n);
    byte data[] = new byte[buflen];
    while (n > 0) {
        int r = read(data, 0, (int) Math.min((long) buflen, n));
        if (r < 0) {
        break;
        }
        n -= r;
    }
    return numbytes - n;
    }

    /**
     * Returns the number of bytes that can be read without blocking.
     * @return the number of immediately available bytes
     */
    public int available() throws IOException {
    return impl.available();
    }

    /**
     * Closes the stream.
     */
    public void close() throws IOException {
    impl.close();
    }

    /**
     * Overrides finalize, the fd is closed by the Socket.
     */
    protected void finalize() {}
}