Fast Multi ByteArrayInputStream
/* * @(#)$Id: codetemplate_xbird.xml 943 2006-09-13 07:03:37Z yui $ * * Copyright 2006-2008 Makoto YUI * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * Contributors: * Makoto YUI - initial implementation */ //package xbird.util.io; import java.io.IOException; import java.io.InputStream; /** * * <DIV lang="en"></DIV> * <DIV lang="ja"></DIV> * * @author Makoto YUI ([email protected] ) */ public final class FastMultiByteArrayInputStream extends InputStream { private final byte [][] _buffers; private final int _blocksize; private int _pos; private int _count; private byte [] _curBlock; private int _curBlockIdx; private int _curBlockOffset; private boolean _cleanable = false ; // TODO variable block size public FastMultiByteArrayInputStream ( byte [][] buffers, int blockSize, int totalSize ) { if ( buffers == null ) { throw new IllegalArgumentException () ; } this ._buffers = buffers; this ._blocksize = blockSize; this ._pos = 0 ; this ._count = totalSize; this ._curBlock = buffers [ 0 ] ; this ._curBlockIdx = 0 ; this ._curBlockOffset = 0 ; } public void setCleanable ( boolean cleanable ) { this ._cleanable = cleanable; } public int read () { final byte [] block = getCurBlock ( _pos++ ) ; return ( _pos < _count ) ? ( block [ _curBlockOffset++ ] & 0xff ) : - 1 ; } @Override public int read ( final byte b [] , int off, int len ) { if ( b == null ) { throw new NullPointerException () ; } else if ( off < 0 || len < 0 || len > b.length - off ) { throw new IndexOutOfBoundsException () ; } if ( _pos >= _count ) { return - 1 ; } if ( _pos + len > _count ) { len = _count - _pos; } if ( len <= 0 ) { return 0 ; } final int limit = _pos + len; for ( int n = _pos; n < limit; ) { final byte [] block = getCurBlock ( n ) ; final int numleft = _blocksize - _curBlockOffset; final int copylen = Math.min ( limit - n, numleft ) ; System.arraycopy ( block, _curBlockOffset, b, off, copylen ) ; _curBlockOffset += copylen; off += copylen; n += copylen; } _pos += len; return len; } private byte [] getCurBlock ( final int pos ) { if ( _curBlockOffset < _blocksize ) { return _curBlock; } else { if ( _cleanable ) { _buffers [ _curBlockIdx ] = null ; } final int nextBlockIdx = ++_curBlockIdx; final byte [] block = _buffers [ nextBlockIdx ] ; this ._curBlock = block; this ._curBlockOffset = 0 ; return block; } } @Override public long skip ( long n ) { if ( _pos + n > _count ) { n = _count - _pos; } if ( n < 0 ) { return 0 ; } _pos += n; return n; } @Override public int available () { return _count - _pos; } @Override public boolean markSupported () { return false ; } @Override public void mark ( int readAheadLimit ) { throw new UnsupportedOperationException () ; } @Override public void reset () { throw new UnsupportedOperationException () ; } @Override public void close () throws IOException {} }
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