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117 lines
3.0 KiB
117 lines
3.0 KiB
/*
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* Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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package java.util.zip;
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import java.io.FilterInputStream;
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import java.io.InputStream;
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import java.io.IOException;
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/**
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* An input stream that also maintains a checksum of the data being read.
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* The checksum can then be used to verify the integrity of the input data.
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*
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* @see Checksum
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* @author David Connelly
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*/
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public
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class CheckedInputStream extends FilterInputStream {
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private Checksum cksum;
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/**
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* Creates an input stream using the specified Checksum.
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* @param in the input stream
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* @param cksum the Checksum
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*/
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public CheckedInputStream(InputStream in, Checksum cksum) {
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super(in);
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this.cksum = cksum;
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}
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/**
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* Reads a byte. Will block if no input is available.
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* @return the byte read, or -1 if the end of the stream is reached.
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* @exception IOException if an I/O error has occurred
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*/
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public int read() throws IOException {
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int b = in.read();
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if (b != -1) {
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cksum.update(b);
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}
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return b;
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}
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/**
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* Reads into an array of bytes. If <code>len</code> is not zero, the method
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* blocks until some input is available; otherwise, no
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* bytes are read and <code>0</code> is returned.
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* @param buf the buffer into which the data is read
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* @param off the start offset in the destination array <code>b</code>
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* @param len the maximum number of bytes read
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* @return the actual number of bytes read, or -1 if the end
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* of the stream is reached.
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* @exception NullPointerException If <code>buf</code> is <code>null</code>.
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* @exception IndexOutOfBoundsException If <code>off</code> is negative,
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* <code>len</code> is negative, or <code>len</code> is greater than
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* <code>buf.length - off</code>
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* @exception IOException if an I/O error has occurred
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*/
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public int read(byte[] buf, int off, int len) throws IOException {
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len = in.read(buf, off, len);
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if (len != -1) {
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cksum.update(buf, off, len);
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}
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return len;
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}
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/**
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* Skips specified number of bytes of input.
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* @param n the number of bytes to skip
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* @return the actual number of bytes skipped
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* @exception IOException if an I/O error has occurred
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*/
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public long skip(long n) throws IOException {
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byte[] buf = new byte[512];
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long total = 0;
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while (total < n) {
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long len = n - total;
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len = read(buf, 0, len < buf.length ? (int)len : buf.length);
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if (len == -1) {
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return total;
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}
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total += len;
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}
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return total;
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}
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/**
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* Returns the Checksum for this input stream.
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* @return the Checksum value
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*/
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public Checksum getChecksum() {
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return cksum;
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}
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}
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