streams/BufferedOutputStream.java

   1 package be.nikiroo.utils.streams;
   2
   3 import java.io.IOException;
   4 import java.io.InputStream;
   5 import java.io.OutputStream;
   6
   7 /**
   8  * A simple {@link OutputStream} that is buffered with a bytes array.
   9  * <p>
  10  * It is mostly intended to be used as a base class to create new
  11  * {@link OutputStream}s with special operation modes, and to give some default
  12  * methods.
  13  *
  14  * @author niki
  15  */
  16 public class BufferedOutputStream extends OutputStream {
  17         /** The current position in the buffer. */
  18         protected int start;
  19         /** The index of the last usable position of the buffer. */
  20         protected int stop;
  21         /** The buffer itself. */
  22         protected byte[] buffer;
  23         /** An End-Of-File (or buffer, here) marker. */
  24         protected boolean eof;
  25         /** The actual under-laying stream. */
  26         protected OutputStream out;
  27         /** The number of bytes written to the under-laying stream. */
  28         protected long bytesWritten;
  29         /**
  30          * Can bypass the flush process for big writes (will directly write to the
  31          * under-laying buffer if the array to write is &gt; the internal buffer
  32          * size).
  33          * <p>
  34          * By default, this is true.
  35          */
  36         protected boolean bypassFlush = true;
  37
  38         private boolean closed;
  39         private int openCounter;
  40         private byte[] b1;
  41
  42         /**
  43          * Create a new {@link BufferedInputStream} that wraps the given
  44          * {@link InputStream}.
  45          *
  46          * @param out
  47          *            the {@link OutputStream} to wrap
  48          */
  49         public BufferedOutputStream(OutputStream out) {
  50                 this.out = out;
  51
  52                 this.buffer = new byte[4096];
  53                 this.b1 = new byte[1];
  54                 this.start = 0;
  55                 this.stop = 0;
  56         }
  57
  58         @Override
  59         public void write(int b) throws IOException {
  60                 b1[0] = (byte) b;
  61                 write(b1, 0, 1);
  62         }
  63
  64         @Override
  65         public void write(byte[] b) throws IOException {
  66                 write(b, 0, b.length);
  67         }
  68
  69         @Override
  70         public void write(byte[] source, int sourceOffset, int sourceLength)
  71                         throws IOException {
  72
  73                 checkClose();
  74
  75                 if (source == null) {
  76                         throw new NullPointerException();
  77                 } else if ((sourceOffset < 0) || (sourceOffset > source.length)
  78                                 || (sourceLength < 0)
  79                                 || ((sourceOffset + sourceLength) > source.length)
  80                                 || ((sourceOffset + sourceLength) < 0)) {
  81                         throw new IndexOutOfBoundsException();
  82                 } else if (sourceLength == 0) {
  83                         return;
  84                 }
  85
  86                 if (bypassFlush && sourceLength >= buffer.length) {
  87                         /*
  88                          * If the request length exceeds the size of the output buffer,
  89                          * flush the output buffer and then write the data directly. In this
  90                          * way buffered streams will cascade harmlessly.
  91                          */
  92                         flush(false);
  93                         out.write(source, sourceOffset, sourceLength);
  94                         bytesWritten += (sourceLength - sourceOffset);
  95                         return;
  96                 }
  97
  98                 int done = 0;
  99                 while (done < sourceLength) {
 100                         if (available() <= 0) {
 101                                 flush(false);
 102                         }
 103
 104                         int now = Math.min(sourceLength - done, available());
 105                         System.arraycopy(source, sourceOffset + done, buffer, stop, now);
 106                         stop += now;
 107                         done += now;
 108                 }
 109         }
 110
 111         /**
 112          * The available space in the buffer.
 113          *
 114          * @return the space in bytes
 115          */
 116         private int available() {
 117                 if (closed) {
 118                         return 0;
 119                 }
 120
 121                 return Math.max(0, buffer.length - stop - 1);
 122         }
 123
 124         /**
 125          * The number of bytes written to the under-laying {@link OutputStream}.
 126          *
 127          * @return the number of bytes
 128          */
 129         public long getBytesWritten() {
 130                 return bytesWritten;
 131         }
 132
 133         /**
 134          * Return this very same {@link BufferedInputStream}, but keep a counter of
 135          * how many streams were open this way. When calling
 136          * {@link BufferedInputStream#close()}, decrease this counter if it is not
 137          * already zero instead of actually closing the stream.
 138          * <p>
 139          * You are now responsible for it &mdash; you <b>must</b> close it.
 140          * <p>
 141          * This method allows you to use a wrapping stream around this one and still
 142          * close the wrapping stream.
 143          *
 144          * @return the same stream, but you are now responsible for closing it
 145          *
 146          * @throws IOException
 147          *             in case of I/O error or if the stream is closed
 148          */
 149         public synchronized OutputStream open() throws IOException {
 150                 checkClose();
 151                 openCounter++;
 152                 return this;
 153         }
 154
 155         /**
 156          * Check that the stream was not closed, and throw an {@link IOException} if
 157          * it was.
 158          *
 159          * @throws IOException
 160          *             if it was closed
 161          */
 162         protected void checkClose() throws IOException {
 163                 if (closed) {
 164                         throw new IOException(
 165                                         "This BufferedInputStream was closed, you cannot use it anymore.");
 166                 }
 167         }
 168
 169         @Override
 170         public void flush() throws IOException {
 171                 flush(true);
 172         }
 173
 174         /**
 175          * Flush the {@link BufferedOutputStream}, write the current buffered data
 176          * to (and optionally also flush) the under-laying stream.
 177          * <p>
 178          * If {@link BufferedOutputStream#bypassFlush} is false, all writes to the
 179          * under-laying stream are done in this method.
 180          * <p>
 181          * This can be used if you want to write some data in the under-laying
 182          * stream yourself (in that case, flush this {@link BufferedOutputStream}
 183          * with or without flushing the under-laying stream, then you can write to
 184          * the under-laying stream).
 185          *
 186          * @param includingSubStream
 187          *            also flush the under-laying stream
 188          * @throws IOException
 189          *             in case of I/O error
 190          */
 191         public void flush(boolean includingSubStream) throws IOException {
 192                 if (stop > start) {
 193                         out.write(buffer, start, stop - start);
 194                         bytesWritten += (stop - start);
 195                 }
 196                 start = 0;
 197                 stop = 0;
 198
 199                 if (includingSubStream) {
 200                         out.flush();
 201                 }
 202         }
 203
 204         /**
 205          * Closes this stream and releases any system resources associated with the
 206          * stream.
 207          * <p>
 208          * Including the under-laying {@link InputStream}.
 209          * <p>
 210          * <b>Note:</b> if you called the {@link BufferedInputStream#open()} method
 211          * prior to this one, it will just decrease the internal count of how many
 212          * open streams it held and do nothing else. The stream will actually be
 213          * closed when you have called {@link BufferedInputStream#close()} once more
 214          * than {@link BufferedInputStream#open()}.
 215          *
 216          * @exception IOException
 217          *                in case of I/O error
 218          */
 219         @Override
 220         public synchronized void close() throws IOException {
 221                 close(true);
 222         }
 223
 224         /**
 225          * Closes this stream and releases any system resources associated with the
 226          * stream.
 227          * <p>
 228          * Including the under-laying {@link InputStream} if
 229          * <tt>incudingSubStream</tt> is true.
 230          * <p>
 231          * You can call this method multiple times, it will not cause an
 232          * {@link IOException} for subsequent calls.
 233          * <p>
 234          * <b>Note:</b> if you called the {@link BufferedInputStream#open()} method
 235          * prior to this one, it will just decrease the internal count of how many
 236          * open streams it held and do nothing else. The stream will actually be
 237          * closed when you have called {@link BufferedInputStream#close()} once more
 238          * than {@link BufferedInputStream#open()}.
 239          *
 240          * @param includingSubStream
 241          *            also close the under-laying stream
 242          *
 243          * @exception IOException
 244          *                in case of I/O error
 245          */
 246         public synchronized void close(boolean includingSubStream)
 247                         throws IOException {
 248                 if (!closed) {
 249                         if (openCounter > 0) {
 250                                 openCounter--;
 251                         } else {
 252                                 closed = true;
 253                                 flush(includingSubStream);
 254                                 if (includingSubStream && out != null) {
 255                                         out.close();
 256                                 }
 257                         }
 258                 }
 259         }
 260 }