Unless otherwise noted, passing a {@code null} argument to a constructor * or method in this class will cause a {@link NullPointerException} to be * thrown. * *
* If a decompressor is specified when creating a {@code InflaterInputStream}, it is the * responsibility of the caller to {@linkplain Inflater#close close} the * decompressor after closing the input stream. * * @apiNote * The {@link #close} method should be called to release resources used by this * stream, either directly, or with the {@code try}-with-resources statement. * * @see Inflater * @author David Connelly * @since 1.1 */ public class InflaterInputStream extends FilterInputStream { /** * Decompressor for this stream. */ protected Inflater inf; /** * Input buffer for decompression. */ protected byte[] buf; /** * The total number of bytes read into the input buffer. */ protected int len; private boolean closed = false; // this flag is set to true after EOF has reached private boolean reachEOF = false; /** * Check to make sure that this stream has not been closed */ private void ensureOpen() throws IOException { if (closed) { throw new IOException("Stream closed"); } } /** * Creates a new input stream with the specified decompressor and * buffer size. *
* {@linkplain #close() Closing} this input stream * {@linkplain ##decompressor-usage will not close} the given * {@linkplain Inflater decompressor}. * * @param in the input stream * @param inf the decompressor ("inflater") * @param size the input buffer size * @throws IllegalArgumentException if {@code size <= 0} */ public InflaterInputStream(InputStream in, Inflater inf, int size) { super(in); if (in == null || inf == null) { throw new NullPointerException(); } else if (size <= 0) { throw new IllegalArgumentException("buffer size <= 0"); } this.inf = inf; buf = new byte[size]; } /** * Creates a new input stream with the specified decompressor and a * default buffer size. *
* {@linkplain #close() Closing} this input stream * {@linkplain ##decompressor-usage will not close} the given * {@linkplain Inflater decompressor}. * * @param in the input stream * @param inf the decompressor ("inflater") */ public InflaterInputStream(InputStream in, Inflater inf) { this(in, inf, 512); } boolean usesDefaultInflater = false; /** * Creates a new input stream and decompressor with a * default buffer size. *
* The decompressor will be closed when this input stream * is {@linkplain #close() closed}. * * @param in the input stream */ public InflaterInputStream(InputStream in) { this(in, in != null ? new Inflater() : null); usesDefaultInflater = true; } private final byte[] singleByteBuf = new byte[1]; /** * Reads a byte of uncompressed data. This method will block until * enough input is available for decompression. * @return the byte read, or -1 if end of compressed input is reached * @throws IOException if an I/O error has occurred */ @Override public int read() throws IOException { ensureOpen(); return read(singleByteBuf, 0, 1) == -1 ? -1 : Byte.toUnsignedInt(singleByteBuf[0]); } /** * Reads uncompressed data into an array of bytes, returning the number of inflated * bytes. If {@code len} is not zero, the method will block until some input can be * decompressed; otherwise, no bytes are read and {@code 0} is returned. *
* If this method returns a nonzero integer n then {@code buf[off]} * through {@code buf[off+}n{@code -1]} contain the uncompressed * data. The content of elements {@code buf[off+}n{@code ]} through * {@code buf[off+}len{@code -1]} is undefined, contrary to the * specification of the {@link java.io.InputStream InputStream} superclass, * so an implementation is free to modify these elements during the inflate * operation. If this method returns {@code -1} or throws an exception then * the content of {@code buf[off]} through {@code buf[off+}len{@code * -1]} is undefined. * * @param b the buffer into which the data is read * @param off the start offset in the destination array {@code b} * @param len the maximum number of bytes read * @return the actual number of bytes inflated, or -1 if the end of the * compressed input is reached or a preset dictionary is needed * @throws IndexOutOfBoundsException If {@code off} is negative, * {@code len} is negative, or {@code len} is greater than * {@code b.length - off} * @throws ZipException if a ZIP format error has occurred * @throws IOException if an I/O error has occurred */ @Override public int read(byte[] b, int off, int len) throws IOException { ensureOpen(); if (b == null) { throw new NullPointerException(); } Objects.checkFromIndexSize(off, len, b.length); if (len == 0) { return 0; } try { int n; do { if (inf.finished() || inf.needsDictionary()) { reachEOF = true; return -1; } if (inf.needsInput() && !inf.hasPendingOutput()) { // Even if needsInput() is true, the native inflater may have some // buffered data which couldn't fit in to the output buffer during the // last call to inflate. Consume that buffered data first before calling // fill() to avoid an EOF error if no more input is available and the // next call to inflate will finish the inflation. fill(); } } while ((n = inf.inflate(b, off, len)) == 0); return n; } catch (DataFormatException e) { String s = e.getMessage(); throw new ZipException(s != null ? s : "Invalid ZLIB data format"); } } /** * Returns 0 after EOF has been reached, otherwise always return 1. *
* Programs should not count on this method to return the actual number * of bytes that could be read without blocking. * * @return 1 before EOF and 0 after EOF. * @throws IOException if an I/O error occurs. * */ @Override public int available() throws IOException { ensureOpen(); if (reachEOF) { return 0; } else if (inf.finished()) { // the end of the compressed data stream has been reached reachEOF = true; return 0; } else { return 1; } } /** * Skips specified number of bytes of uncompressed data. * This method may block until the specified number of bytes are skipped * or end of stream is reached. * * @implNote * This method skips at most {@code Integer.MAX_VALUE} bytes. * * @param n the number of bytes to skip. If {@code n} is zero then no bytes are skipped. * @return the actual number of bytes skipped, which might be zero * @throws IOException if an I/O error occurs or if this stream is * already closed * @throws IllegalArgumentException if {@code n < 0} */ @Override public long skip(long n) throws IOException { if (n < 0) { throw new IllegalArgumentException("negative skip length"); } ensureOpen(); int max = (int)Math.min(n, Integer.MAX_VALUE); int total = 0; byte[] b = new byte[Math.min(max, 512)]; while (total < max) { int len = max - total; if (len > b.length) { len = b.length; } len = read(b, 0, len); if (len == -1) { reachEOF = true; break; } total += len; } return total; } /** * Closes this input stream and releases any system resources associated * with the stream. * * @throws IOException if an I/O error has occurred */ @Override public void close() throws IOException { if (!closed) { if (usesDefaultInflater) inf.end(); in.close(); closed = true; } } /** * Fills input buffer with more data to decompress. * @implSpec * This method will read up to {@link #buf}.length bytes into the input * buffer, {@link #buf}, starting at element {@code 0}. The {@link #len} * field will be set to the number of bytes read. * @throws IOException if an I/O error has occurred * @throws EOFException if the end of input stream has been reached * unexpectedly */ protected void fill() throws IOException { ensureOpen(); len = in.read(buf, 0, buf.length); if (len == -1) { throw new EOFException("Unexpected end of ZLIB input stream"); } inf.setInput(buf, 0, len); } /** * Tests if this input stream supports the {@code mark} and * {@code reset} methods. The {@code markSupported} * method of {@code InflaterInputStream} returns * {@code false}. * * @return a {@code boolean} indicating if this stream type supports * the {@code mark} and {@code reset} methods. * @see java.io.InputStream#mark(int) * @see java.io.InputStream#reset() */ @Override public boolean markSupported() { return false; } /** * Marks the current position in this input stream. * * @implSpec The {@code mark} method of {@code InflaterInputStream} * does nothing. * * @param readlimit the maximum limit of bytes that can be read before * the mark position becomes invalid. * @see java.io.InputStream#reset() */ @Override public void mark(int readlimit) { } /** * Repositions this stream to the position at the time the * {@code mark} method was last called on this input stream. * * @implSpec The method {@code reset} for class * {@code InflaterInputStream} does nothing except throw an * {@code IOException}. * * @throws IOException if this method is invoked. * @see java.io.InputStream#mark(int) * @see java.io.IOException */ @Override public void reset() throws IOException { throw new IOException("mark/reset not supported"); } }