| |
| /* ==================================================================== |
| Licensed to the Apache Software Foundation (ASF) under one or more |
| contributor license agreements. See the NOTICE file distributed with |
| this work for additional information regarding copyright ownership. |
| The ASF licenses this file to You 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. |
| ==================================================================== */ |
| |
| |
| package org.apache.poi.poifs.filesystem; |
| |
| import java.io.*; |
| |
| /** |
| * This class provides methods to read a DocumentEntry managed by a |
| * Filesystem instance. |
| * |
| * @author Marc Johnson (mjohnson at apache dot org) |
| */ |
| |
| public class DocumentInputStream |
| extends InputStream |
| { |
| |
| // current offset into the Document |
| private int _current_offset; |
| |
| // current marked offset into the Document (used by mark and |
| // reset) |
| private int _marked_offset; |
| |
| // the Document's size |
| private int _document_size; |
| |
| // have we been closed? |
| private boolean _closed; |
| |
| // the actual Document |
| private POIFSDocument _document; |
| |
| // buffer used to read one byte at a time |
| private byte[] _tiny_buffer; |
| |
| // returned by read operations if we're at end of document |
| static private final int EOD = -1; |
| |
| /** |
| * Create an InputStream from the specified DocumentEntry |
| * |
| * @param document the DocumentEntry to be read |
| * |
| * @exception IOException if the DocumentEntry cannot be opened |
| * (like, maybe it has been deleted?) |
| */ |
| |
| public DocumentInputStream(final DocumentEntry document) |
| throws IOException |
| { |
| _current_offset = 0; |
| _marked_offset = 0; |
| _document_size = document.getSize(); |
| _closed = false; |
| _tiny_buffer = null; |
| if (document instanceof DocumentNode) |
| { |
| _document = (( DocumentNode ) document).getDocument(); |
| } |
| else |
| { |
| throw new IOException("Cannot open internal document storage"); |
| } |
| } |
| |
| /** |
| * Create an InputStream from the specified Document |
| * |
| * @param document the Document to be read |
| * |
| * @exception IOException if the DocumentEntry cannot be opened |
| * (like, maybe it has been deleted?) |
| */ |
| |
| public DocumentInputStream(final POIFSDocument document) |
| throws IOException |
| { |
| _current_offset = 0; |
| _marked_offset = 0; |
| _document_size = document.getSize(); |
| _closed = false; |
| _tiny_buffer = null; |
| _document = document; |
| } |
| |
| /** |
| * Returns the number of bytes that can be read (or skipped over) |
| * from this input stream without blocking by the next caller of a |
| * method for this input stream. The next caller might be the same |
| * thread or or another thread. |
| * |
| * @return the number of bytes that can be read from this input |
| * stream without blocking. |
| * |
| * @exception IOException on error (such as the stream has been |
| * closed) |
| */ |
| |
| public int available() |
| throws IOException |
| { |
| dieIfClosed(); |
| return _document_size - _current_offset; |
| } |
| |
| /** |
| * Closes this input stream and releases any system resources |
| * associated with the stream. |
| * |
| * @exception IOException |
| */ |
| |
| public void close() |
| throws IOException |
| { |
| _closed = true; |
| } |
| |
| /** |
| * Marks the current position in this input stream. A subsequent |
| * call to the reset method repositions this stream at the last |
| * marked position so that subsequent reads re-read the same |
| * bytes. |
| * <p> |
| * The readlimit arguments tells this input stream to allow that |
| * many bytes to be read before the mark position gets |
| * invalidated. This implementation, however, does not care. |
| * <p> |
| * The general contract of mark is that, if the method |
| * markSupported returns true, the stream somehow remembers all |
| * the bytes read after the call to mark and stands ready to |
| * supply those same bytes again if and whenever the method reset |
| * is called. However, the stream is not required to remember any |
| * data at all if more than readlimit bytes are read from the |
| * stream before reset is called. But this stream will. |
| * |
| * @param ignoredReadlimit the maximum limit of bytes that can be |
| * read before the mark position becomes |
| * invalid. Ignored by this |
| * implementation. |
| */ |
| |
| public void mark(int ignoredReadlimit) |
| { |
| _marked_offset = _current_offset; |
| } |
| |
| /** |
| * Tests if this input stream supports the mark and reset methods. |
| * |
| * @return true |
| */ |
| |
| public boolean markSupported() |
| { |
| return true; |
| } |
| |
| /** |
| * Reads the next byte of data from the input stream. The value |
| * byte is returned as an int in the range 0 to 255. If no byte is |
| * available because the end of the stream has been reached, the |
| * value -1 is returned. The definition of this method in |
| * java.io.InputStream allows this method to block, but it won't. |
| * |
| * @return the next byte of data, or -1 if the end of the stream |
| * is reached. |
| * |
| * @exception IOException |
| */ |
| |
| public int read() |
| throws IOException |
| { |
| dieIfClosed(); |
| if (atEOD()) |
| { |
| return EOD; |
| } |
| if (_tiny_buffer == null) |
| { |
| _tiny_buffer = new byte[ 1 ]; |
| } |
| _document.read(_tiny_buffer, _current_offset++); |
| return ((int)_tiny_buffer[ 0 ]) & 0x000000FF; |
| } |
| |
| /** |
| * Reads some number of bytes from the input stream and stores |
| * them into the buffer array b. The number of bytes actually read |
| * is returned as an integer. The definition of this method in |
| * java.io.InputStream allows this method to block, but it won't. |
| * <p> |
| * If b is null, a NullPointerException is thrown. If the length |
| * of b is zero, then no bytes are read and 0 is returned; |
| * otherwise, there is an attempt to read at least one byte. If no |
| * byte is available because the stream is at end of file, the |
| * value -1 is returned; otherwise, at least one byte is read and |
| * stored into b. |
| * <p> |
| * The first byte read is stored into element b[0], the next one |
| * into b[1], and so on. The number of bytes read is, at most, |
| * equal to the length of b. Let k be the number of bytes actually |
| * read; these bytes will be stored in elements b[0] through |
| * b[k-1], leaving elements b[k] through b[b.length-1] unaffected. |
| * <p> |
| * If the first byte cannot be read for any reason other than end |
| * of file, then an IOException is thrown. In particular, an |
| * IOException is thrown if the input stream has been closed. |
| * <p> |
| * The read(b) method for class InputStream has the same effect as: |
| * <p> |
| * <code>read(b, 0, b.length)</code> |
| * |
| * @param b the buffer into which the data is read. |
| * |
| * @return the total number of bytes read into the buffer, or -1 |
| * if there is no more data because the end of the stream |
| * has been reached. |
| * |
| * @exception IOException |
| * @exception NullPointerException |
| */ |
| |
| public int read(final byte [] b) |
| throws IOException, NullPointerException |
| { |
| return read(b, 0, b.length); |
| } |
| |
| /** |
| * Reads up to len bytes of data from the input stream into an |
| * array of bytes. An attempt is made to read as many as len |
| * bytes, but a smaller number may be read, possibly zero. The |
| * number of bytes actually read is returned as an integer. |
| * <p> |
| * The definition of this method in java.io.InputStream allows it |
| * to block, but it won't. |
| * <p> |
| * If b is null, a NullPointerException is thrown. |
| * <p> |
| * If off is negative, or len is negative, or off+len is greater |
| * than the length of the array b, then an |
| * IndexOutOfBoundsException is thrown. |
| * <p> |
| * If len is zero, then no bytes are read and 0 is returned; |
| * otherwise, there is an attempt to read at least one byte. If no |
| * byte is available because the stream is at end of file, the |
| * value -1 is returned; otherwise, at least one byte is read and |
| * stored into b. |
| * <p> |
| * The first byte read is stored into element b[off], the next one |
| * into b[off+1], and so on. The number of bytes read is, at most, |
| * equal to len. Let k be the number of bytes actually read; these |
| * bytes will be stored in elements b[off] through b[off+k-1], |
| * leaving elements b[off+k] through b[off+len-1] unaffected. |
| * <p> |
| * In every case, elements b[0] through b[off] and elements |
| * b[off+len] through b[b.length-1] are unaffected. |
| * <p> |
| * If the first byte cannot be read for any reason other than end |
| * of file, then an IOException is thrown. In particular, an |
| * IOException is thrown if the input stream has been closed. |
| * |
| * @param b the buffer into which the data is read. |
| * @param off the start offset in array b at which the data is |
| * written. |
| * @param len the maximum number of bytes to read. |
| * |
| * @return the total number of bytes read into the buffer, or -1 |
| * if there is no more data because the end of the stream |
| * has been reached. |
| * |
| * @exception IOException |
| * @exception NullPointerException |
| * @exception IndexOutOfBoundsException |
| */ |
| |
| public int read(final byte [] b, final int off, final int len) |
| throws IOException, NullPointerException, IndexOutOfBoundsException |
| { |
| dieIfClosed(); |
| if (b == null) |
| { |
| throw new NullPointerException("buffer is null"); |
| } |
| if ((off < 0) || (len < 0) || (b.length < (off + len))) |
| { |
| throw new IndexOutOfBoundsException( |
| "can't read past buffer boundaries"); |
| } |
| if (len == 0) |
| { |
| return 0; |
| } |
| if (atEOD()) |
| { |
| return EOD; |
| } |
| int limit = Math.min(available(), len); |
| |
| if ((off == 0) && (limit == b.length)) |
| { |
| _document.read(b, _current_offset); |
| } |
| else |
| { |
| byte[] buffer = new byte[ limit ]; |
| |
| _document.read(buffer, _current_offset); |
| System.arraycopy(buffer, 0, b, off, limit); |
| } |
| _current_offset += limit; |
| return limit; |
| } |
| |
| /** |
| * Repositions this stream to the position at the time the mark |
| * method was last called on this input stream. |
| * <p> |
| * The general contract of reset is: |
| * <p> |
| * <ul> |
| * <li> |
| * If the method markSupported returns true, then: |
| * <ul> |
| * <li> |
| * If the method mark has not been called since the |
| * stream was created, or the number of bytes read |
| * from the stream since mark was last called is |
| * larger than the argument to mark at that last |
| * call, then an IOException might be thrown. |
| * </li> |
| * <li> |
| * If such an IOException is not thrown, then the |
| * stream is reset to a state such that all the |
| * bytes read since the most recent call to mark |
| * (or since the start of the file, if mark has not |
| * been called) will be resupplied to subsequent |
| * callers of the read method, followed by any |
| * bytes that otherwise would have been the next |
| * input data as of the time of the call to reset. |
| * </li> |
| * </ul> |
| * </li> |
| * <li> |
| * If the method markSupported returns false, then: |
| * <ul> |
| * <li> |
| * The call to reset may throw an IOException. |
| * </li> |
| * <li> |
| * If an IOException is not thrown, then the |
| * stream is reset to a fixed state that depends |
| * on the particular type of the input and how it |
| * was created. The bytes that will be supplied to |
| * subsequent callers of the read method depend on |
| * the particular type of the input stream. |
| * </li> |
| * </ul> |
| * </li> |
| * </ul> |
| * <p> |
| * All well and good ... this class's markSupported method returns |
| * true and this method does not care whether you've called mark |
| * at all, or whether you've exceeded the number of bytes |
| * specified in the last call to mark. We're basically walking a |
| * byte array ... mark and reset to your heart's content. |
| */ |
| |
| public void reset() |
| { |
| _current_offset = _marked_offset; |
| } |
| |
| /** |
| * Skips over and discards n bytes of data from this input |
| * stream. The skip method may, for a variety of reasons, end up |
| * skipping over some smaller number of bytes, possibly 0. This |
| * may result from any of a number of conditions; reaching end of |
| * file before n bytes have been skipped is only one |
| * possibility. The actual number of bytes skipped is returned. If |
| * n is negative, no bytes are skipped. |
| * |
| * @param n the number of bytes to be skipped. |
| * |
| * @return the actual number of bytes skipped. |
| * |
| * @exception IOException |
| */ |
| |
| public long skip(final long n) |
| throws IOException |
| { |
| dieIfClosed(); |
| if (n < 0) |
| { |
| return 0; |
| } |
| int new_offset = _current_offset + ( int ) n; |
| |
| if (new_offset < _current_offset) |
| { |
| |
| // wrap around in converting a VERY large long to an int |
| new_offset = _document_size; |
| } |
| else if (new_offset > _document_size) |
| { |
| new_offset = _document_size; |
| } |
| long rval = new_offset - _current_offset; |
| |
| _current_offset = new_offset; |
| return rval; |
| } |
| |
| private void dieIfClosed() |
| throws IOException |
| { |
| if (_closed) |
| { |
| throw new IOException( |
| "cannot perform requested operation on a closed stream"); |
| } |
| } |
| |
| private boolean atEOD() |
| { |
| return _current_offset == _document_size; |
| } |
| } // end public class DocumentInputStream |
| |