len is not
+ * zero, the method will block until some input can be decompressed; otherwise,
+ * no bytes are read and 0 is returned.
+ * @param b the buffer into which the data is read
+ * @param off the start offset in the destination array b
+ * @param len the maximum number of bytes read
+ * @return the actual number of bytes read, or -1 if the end of the
+ * compressed input is reached or a preset dictionary is needed
+ * @exception NullPointerException If b is null.
+ * @exception IndexOutOfBoundsException If off is negative,
+ * len is negative, or len is greater than
+ * b.length - off
+ * @exception ZipException if a ZIP format error has occurred
+ * @exception IOException if an I/O error has occurred
+ */
+ public int read(byte[] b, int off, int len) throws IOException {
+ ensureOpen();
+ if (b == null) {
+ throw new NullPointerException();
+ } else if (off < 0 || len < 0 || len > b.length - off) {
+ throw new IndexOutOfBoundsException();
+ } else if (len == 0) {
+ return 0;
+ }
+ try {
+ int n;
+ while ((n = inf.inflate(b, off, len)) == 0) {
+ if (inf.finished() || inf.needsDictionary()) {
+ reachEOF = true;
+ return -1;
+ }
+ if (inf.needsInput()) {
+ fill();
+ }
+ }
+ 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.
+ * @exception IOException if an I/O error occurs.
+ *
+ */
+ public int available() throws IOException {
+ ensureOpen();
+ if (reachEOF) {
+ return 0;
+ } else {
+ return 1;
+ }
+ }
+
+ private byte[] b = new byte[512];
+
+ /**
+ * Skips specified number of bytes of uncompressed data.
+ * @param n the number of bytes to skip
+ * @return the actual number of bytes skipped.
+ * @exception IOException if an I/O error has occurred
+ * @exception IllegalArgumentException if n < 0
+ */
+ 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;
+ 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.
+ * @exception IOException if an I/O error has occurred
+ */
+ public void close() throws IOException {
+ if (!closed) {
+ if (usesDefaultInflater)
+ inf.end();
+ in.close();
+ closed = true;
+ }
+ }
+
+ /**
+ * Fills input buffer with more data to decompress.
+ * @exception IOException if an I/O error has occurred
+ */
+ 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 mark and
+ * reset methods. The markSupported
+ * method of InflaterInputStream returns
+ * false.
+ *
+ * @return a boolean indicating if this stream type supports
+ * the mark and reset methods.
+ * @see java.io.InputStream#mark(int)
+ * @see java.io.InputStream#reset()
+ */
+ public boolean markSupported() {
+ return false;
+ }
+
+ /**
+ * Marks the current position in this input stream.
+ *
+ *
The mark method of 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()
+ */
+ public synchronized void mark(int readlimit) {
+ }
+
+ /**
+ * Repositions this stream to the position at the time the
+ * mark method was last called on this input stream.
+ *
+ *
The method reset for class
+ * InflaterInputStream does nothing except throw an
+ * IOException.
+ *
+ * @exception IOException if this method is invoked.
+ * @see java.io.InputStream#mark(int)
+ * @see java.io.IOException
+ */
+ public synchronized void reset() throws IOException {
+ throw new IOException("mark/reset not supported");
+ }
+}