/*
* @(#)InflaterInputStream.java 1.37 04/06/11
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.util.zip;
import java.io.FilterInputStream;
import java.io.InputStream;
import java.io.IOException;
import java.io.EOFException;
/**
* This class implements a stream filter for uncompressing data in the
* "deflate" compression format. It is also used as the basis for other
* decompression filters, such as GZIPInputStream.
*
* @see Inflater
* @version 1.37, 06/11/04
* @author David Connelly
*/
public
class InflaterInputStream extends FilterInputStream {
/**
* Decompressor for this stream.
*/
protected Inflater inf;
/**
* Input buffer for decompression.
*/
protected byte[] buf;
/**
* Length of 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.
* @param in the input stream
* @param inf the decompressor ("inflater")
* @param size the input buffer size
* @exception IllegalArgumentException if size is <= 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.
* @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 with a default decompressor and buffer size.
* @param in the input stream
*/
public InflaterInputStream(InputStream in) {
this(in, new Inflater());
usesDefaultInflater = true;
}
private 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
* @exception IOException if an I/O error has occurred
*/
public int read() throws IOException {
ensureOpen();
return read(singleByteBuf, 0, 1) == -1 ? -1 : singleByteBuf[0] & 0xff;
}
/**
* Reads uncompressed data into an array of bytes. This method will
* block until some input can be decompressed.
* @param b the buffer into which the data is read
* @param off the start offset of the data
* @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 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 ((off | len | (off + len) | (b.length - (off + len))) < 0) {
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.
* <p>
* 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 <code>mark</code> and
* <code>reset</code> methods. The <code>markSupported</code>
* method of <code>InflaterInputStream</code> returns
* <code>false</code>.
*
* @return a <code>boolean</code> indicating if this stream type supports
* the <code>mark</code> and <code>reset</code> 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.
*
* <p> The <code>mark</code> method of <code>InflaterInputStream</code>
* 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
* <code>mark</code> method was last called on this input stream.
*
* <p> The method <code>reset</code> for class
* <code>InflaterInputStream</code> does nothing except throw an
* <code>IOException</code>.
*
* @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");
}
}
|
