+ * It is mostly intended to be used as a base class to create new + * {@link InputStream}s with special operation modes, and to give some default + * methods. + * + * @author niki + */ +public class BufferedInputStream extends InputStream { + /** The current position in the buffer. */ + protected int start; + /** The index of the last usable position of the buffer. */ + protected int stop; + /** The buffer itself. */ + protected byte[] buffer; + /** An End-Of-File (or buffer, here) marker. */ + protected boolean eof; + + private boolean closed; + private InputStream in; + private int openCounter; + + // special use, prefetched next buffer + private byte[] buffer2; + private int pos2; + private int len2; + private byte[] originalBuffer; + + private long bytesRead; + + /** + * Create a new {@link BufferedInputStream} that wraps the given + * {@link InputStream}. + * + * @param in + * the {@link InputStream} to wrap + */ + public BufferedInputStream(InputStream in) { + this.in = in; + + this.buffer = new byte[4096]; + this.originalBuffer = this.buffer; + this.start = 0; + this.stop = 0; + } + + /** + * Create a new {@link BufferedInputStream} that wraps the given bytes array + * as a data source. + * + * @param in + * the array to wrap, cannot be NULL + */ + public BufferedInputStream(byte[] in) { + this(in, 0, in.length); + } + + /** + * Create a new {@link BufferedInputStream} that wraps the given bytes array + * as a data source. + * + * @param in + * the array to wrap, cannot be NULL + * @param offset + * the offset to start the reading at + * @param length + * the number of bytes to take into account in the array, + * starting from the offset + * + * @throws NullPointerException + * if the array is NULL + * @throws IndexOutOfBoundsException + * if the offset and length do not correspond to the given array + */ + public BufferedInputStream(byte[] in, int offset, int length) { + if (in == null) { + throw new NullPointerException(); + } else if (offset < 0 || length < 0 || length > in.length - offset) { + throw new IndexOutOfBoundsException(); + } + + this.in = null; + + this.buffer = in; + this.originalBuffer = this.buffer; + this.start = offset; + this.stop = length; + } + + /** + * Return this very same {@link BufferedInputStream}, but keep a counter of + * how many streams were open this way. When calling + * {@link BufferedInputStream#close()}, decrease this counter if it is not + * already zero instead of actually closing the stream. + *
+ * You are now responsible for it — you must close it. + *
+ * This method allows you to use a wrapping stream around this one and still + * close the wrapping stream. + * + * @return the same stream, but you are now responsible for closing it + * + * @throws IOException + * in case of I/O error or if the stream is closed + */ + public synchronized InputStream open() throws IOException { + checkClose(); + openCounter++; + return this; + } + + /** + * Check if the current content (what will be read next) starts with the + * given search term. + *
+ * Note: the search term size must be smaller or equal the internal + * buffer size. + * + * @param search + * the term to search for + * + * @return TRUE if the content that will be read starts with it + * + * @throws IOException + * in case of I/O error or if the size of the search term is + * greater than the internal buffer + */ + public boolean startsWiths(String search) throws IOException { + return startsWith(search.getBytes("UTF-8")); + } + + /** + * Check if the current content (what will be read next) starts with the + * given search term. + *
+ * Note: the search term size must be smaller or equal the internal + * buffer size. + * + * @param search + * the term to search for + * + * @return TRUE if the content that will be read starts with it + * + * @throws IOException + * in case of I/O error or if the size of the search term is + * greater than the internal buffer + */ + public boolean startsWith(byte[] search) throws IOException { + if (search.length > originalBuffer.length) { + throw new IOException( + "This stream does not support searching for more than " + + buffer.length + " bytes"); + } + + checkClose(); + + if (available() < search.length) { + preRead(); + } + + if (available() >= search.length) { + // Easy path + return startsWith(search, buffer, start, stop); + } else if (!eof) { + // Harder path + if (buffer2 == null && buffer.length == originalBuffer.length) { + buffer2 = Arrays.copyOf(buffer, buffer.length * 2); + + pos2 = buffer.length; + len2 = in.read(buffer2, pos2, buffer.length); + if (len2 > 0) { + bytesRead += len2; + } + + // Note: here, len/len2 = INDEX of last good byte + len2 += pos2; + } + + return startsWith(search, buffer2, pos2, len2); + } + + return false; + } + + /** + * The number of bytes read from the under-laying {@link InputStream}. + * + * @return the number of bytes + */ + public long getBytesRead() { + return bytesRead; + } + + /** + * Check if this stream is totally spent (no more data to read or to + * process). + * + * @return TRUE if it is + */ + public boolean eof() { + return closed || (stop < 0 && !hasMoreData()); + } + + @Override + public int read() throws IOException { + checkClose(); + + preRead(); + if (eof) { + return -1; + } + + return buffer[start++]; + } + + @Override + public int read(byte[] b) throws IOException { + return read(b, 0, b.length); + } + + @Override + public int read(byte[] b, int boff, int blen) throws IOException { + checkClose(); + + if (b == null) { + throw new NullPointerException(); + } else if (boff < 0 || blen < 0 || blen > b.length - boff) { + throw new IndexOutOfBoundsException(); + } else if (blen == 0) { + return 0; + } + + int done = 0; + while (hasMoreData() && done < blen) { + preRead(); + if (hasMoreData()) { + int now = Math.min(blen, stop) - start; + if (now > 0) { + System.arraycopy(buffer, start, b, boff + done, now); + start += now; + done += now; + } + } + } + + return done > 0 ? done : -1; + } + + @Override + public long skip(long n) throws IOException { + if (n <= 0) { + return 0; + } + + long skipped = 0; + while (hasMoreData() && n > 0) { + preRead(); + + long inBuffer = Math.min(n, available()); + start += inBuffer; + n -= inBuffer; + skipped += inBuffer; + } + + return skipped; + } + + @Override + public int available() { + if (closed) { + return 0; + } + + return Math.max(0, stop - start); + } + + /** + * Closes this stream and releases any system resources associated with the + * stream. + *
+ * Including the under-laying {@link InputStream}. + *
+ * Note: if you called the {@link BufferedInputStream#open()} method + * prior to this one, it will just decrease the internal count of how many + * open streams it held and do nothing else. The stream will actually be + * closed when you have called {@link BufferedInputStream#close()} once more + * than {@link BufferedInputStream#open()}. + * + * @exception IOException + * in case of I/O error + */ + @Override + public synchronized void close() throws IOException { + close(true); + } + + /** + * Closes this stream and releases any system resources associated with the + * stream. + *
+ * Including the under-laying {@link InputStream} if + * incudingSubStream is true. + *
+ * You can call this method multiple times, it will not cause an + * {@link IOException} for subsequent calls. + *
+ * Note: if you called the {@link BufferedInputStream#open()} method + * prior to this one, it will just decrease the internal count of how many + * open streams it held and do nothing else. The stream will actually be + * closed when you have called {@link BufferedInputStream#close()} once more + * than {@link BufferedInputStream#open()}. + * + * @param includingSubStream + * also close the under-laying stream + * + * @exception IOException + * in case of I/O error + */ + public synchronized void close(boolean includingSubStream) + throws IOException { + if (!closed) { + if (openCounter > 0) { + openCounter--; + } else { + closed = true; + if (includingSubStream && in != null) { + in.close(); + } + } + } + } + + /** + * Check if we still have some data in the buffer and, if not, fetch some. + * + * @return TRUE if we fetched some data, FALSE if there are still some in + * the buffer + * + * @throws IOException + * in case of I/O error + */ + protected boolean preRead() throws IOException { + boolean hasRead = false; + if (!eof && in != null && start >= stop) { + start = 0; + if (buffer2 != null) { + buffer = buffer2; + start = pos2; + stop = len2; + + buffer2 = null; + pos2 = 0; + len2 = 0; + } else { + buffer = originalBuffer; + + stop = read(in, buffer); + if (stop > 0) { + bytesRead += stop; + } + } + + hasRead = true; + } + + if (start >= stop) { + eof = true; + } + + return hasRead; + } + + /** + * Read the under-laying stream into the local buffer. + * + * @param in + * the under-laying {@link InputStream} + * @param buffer + * the buffer we use in this {@link BufferedInputStream} + * + * @return the number of bytes read + * + * @throws IOException + * in case of I/O error + */ + protected int read(InputStream in, byte[] buffer) throws IOException { + return in.read(buffer); + } + + /** + * We have more data available in the buffer or we can fetch more. + * + * @return TRUE if it is the case, FALSE if not + */ + protected boolean hasMoreData() { + return !closed && !(eof && start >= stop); + } + + /** + * Check that the stream was not closed, and throw an {@link IOException} if + * it was. + * + * @throws IOException + * if it was closed + */ + protected void checkClose() throws IOException { + if (closed) { + throw new IOException( + "This BufferedInputStream was closed, you cannot use it anymore."); + } + } + + /** + * Check if the buffer starts with the given search term (given as an array, + * a start position and a end position). + *
+ * Note: the parameter len is the index of the last + * position, not the length. + *
+ * Note: the search term size must be smaller or equal the internal + * buffer size. + * + * @param search + * the term to search for + * @param buffer + * the buffer to look into + * @param offset + * the offset at which to start the search + * @param len + * the maximum index of the data to check (this is not a + * length, but an index) + * + * @return TRUE if the search content is present at the given location and + * does not exceed the len index + */ + static protected boolean startsWith(byte[] search, byte[] buffer, + int offset, int len) { + + // Check if there even is enough space for it + if (search.length > (len - offset)) { + return false; + } + + boolean same = true; + for (int i = 0; i < search.length; i++) { + if (search[i] != buffer[offset + i]) { + same = false; + break; + } + } + + return same; + } +}