libjava/java/io/InputStream.java

   1 /* Copyright (C) 1998, 1999  Cygnus Solutions
   2
   3    This file is part of libgcj.
   4
   5 This software is copyrighted work licensed under the terms of the
   6 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   7 details.  */
   8
   9 package java.io;
  10
  11 /**
  12  * @author Warren Levy <warrenl@cygnus.com>
  13  * @date October 2, 1998.
  14  */
  15 /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
  16  * "The Java Language Specification", ISBN 0-201-63451-1
  17  * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
  18  * Status:  Believed complete and correct.
  19  */
  20
  21 public abstract class InputStream
  22 {
  23   public InputStream()
  24   {
  25   }
  26
  27   public int available() throws IOException
  28   {
  29     return 0;
  30   }
  31
  32   public void close() throws IOException
  33   {
  34     // Do nothing
  35   }
  36
  37   public void mark(int readlimit)
  38   {
  39     // Do nothing
  40   }
  41
  42   public boolean markSupported()
  43   {
  44     return false;
  45   }
  46
  47   public abstract int read() throws IOException;
  48
  49   public int read(byte[] b) throws IOException
  50   {
  51     return read(b, 0, b.length);
  52   }
  53
  54   public int read(byte[] b, int off, int len) throws IOException
  55   {
  56     if (off < 0 || len < 0 || off + len > b.length)
  57       throw new IndexOutOfBoundsException();
  58     if (b.length == 0)
  59       return 0;
  60
  61     int i, ch;
  62
  63     for (i = 0; i < len; ++i)
  64       try
  65       {
  66         if ((ch = read()) < 0)
  67           return i == 0 ? -1 : i;               // EOF
  68         b[off + i] = (byte) ch;
  69       }
  70       catch (IOException ex)
  71       {
  72         // Only reading the first byte should cause an IOException.
  73         if (i == 0)
  74           throw ex;
  75         return i;
  76       }
  77
  78     return i;
  79   }
  80
  81   public void reset() throws IOException
  82   {
  83     throw new IOException("mark/reset not supported");
  84   }
  85
  86   public long skip(long n) throws IOException
  87   {
  88     // Throw away n bytes by reading them into a temp byte[].
  89     // Limit the temp array to 2Kb so we don't grab too much memory.
  90     final int buflen = n > 2048 ? 2048 : (int) n;
  91     byte[] tmpbuf = new byte[buflen];
  92     final long origN = n;
  93
  94     while (n > 0L)
  95       {
  96         int numread = read(tmpbuf, 0, n > buflen ? buflen : (int) n);
  97         if (numread <= 0)
  98           break;
  99         n -= numread;
 100       }
 101
 102     return origN - n;
 103   }
 104 }