| /* ==================================================================== |
| 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.util; |
| |
| import java.io.ByteArrayOutputStream; |
| import java.io.Closeable; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.io.OutputStream; |
| import java.io.PushbackInputStream; |
| import java.nio.ByteBuffer; |
| import java.nio.channels.ReadableByteChannel; |
| import java.util.zip.CRC32; |
| import java.util.zip.Checksum; |
| |
| import org.apache.poi.EmptyFileException; |
| |
| public final class IOUtils { |
| private static final POILogger logger = POILogFactory.getLogger( IOUtils.class ); |
| |
| private IOUtils() { |
| // no instances of this class |
| } |
| |
| /** |
| * Peeks at the first 8 bytes of the stream. Returns those bytes, but |
| * with the stream unaffected. Requires a stream that supports mark/reset, |
| * or a PushbackInputStream. If the stream has >0 but <8 bytes, |
| * remaining bytes will be zero. |
| * @throws EmptyFileException if the stream is empty |
| */ |
| public static byte[] peekFirst8Bytes(InputStream stream) throws IOException, EmptyFileException { |
| return peekFirstNBytes(stream, 8); |
| } |
| |
| /** |
| * Peeks at the first N bytes of the stream. Returns those bytes, but |
| * with the stream unaffected. Requires a stream that supports mark/reset, |
| * or a PushbackInputStream. If the stream has >0 but <N bytes, |
| * remaining bytes will be zero. |
| * @throws EmptyFileException if the stream is empty |
| */ |
| public static byte[] peekFirstNBytes(InputStream stream, int limit) throws IOException, EmptyFileException { |
| stream.mark(limit); |
| ByteArrayOutputStream bos = new ByteArrayOutputStream(limit); |
| copy(new BoundedInputStream(stream, limit), bos); |
| |
| int readBytes = bos.size(); |
| if (readBytes == 0) { |
| throw new EmptyFileException(); |
| } |
| |
| if (readBytes < limit) { |
| bos.write(new byte[limit-readBytes]); |
| } |
| byte peekedBytes[] = bos.toByteArray(); |
| if(stream instanceof PushbackInputStream) { |
| PushbackInputStream pin = (PushbackInputStream)stream; |
| pin.unread(peekedBytes, 0, readBytes); |
| } else { |
| stream.reset(); |
| } |
| |
| return peekedBytes; |
| } |
| |
| |
| |
| /** |
| * Reads all the data from the input stream, and returns the bytes read. |
| */ |
| public static byte[] toByteArray(InputStream stream) throws IOException { |
| return toByteArray(stream, Integer.MAX_VALUE); |
| } |
| |
| /** |
| * Reads up to {@code length} bytes from the input stream, and returns the bytes read. |
| */ |
| public static byte[] toByteArray(InputStream stream, int length) throws IOException { |
| ByteArrayOutputStream baos = new ByteArrayOutputStream(length == Integer.MAX_VALUE ? 4096 : length); |
| |
| byte[] buffer = new byte[4096]; |
| int totalBytes = 0, readBytes; |
| do { |
| readBytes = stream.read(buffer, 0, Math.min(buffer.length, length-totalBytes)); |
| totalBytes += Math.max(readBytes,0); |
| if (readBytes > 0) { |
| baos.write(buffer, 0, readBytes); |
| } |
| } while (totalBytes < length && readBytes > -1); |
| |
| if (length != Integer.MAX_VALUE && totalBytes < length) { |
| throw new IOException("unexpected EOF"); |
| } |
| |
| return baos.toByteArray(); |
| } |
| |
| |
| /** |
| * Returns an array (that shouldn't be written to!) of the |
| * ByteBuffer. Will be of the requested length, or possibly |
| * longer if that's easier. |
| */ |
| public static byte[] toByteArray(ByteBuffer buffer, int length) { |
| if(buffer.hasArray() && buffer.arrayOffset() == 0) { |
| // The backing array should work out fine for us |
| return buffer.array(); |
| } |
| |
| byte[] data = new byte[length]; |
| buffer.get(data); |
| return data; |
| } |
| |
| /** |
| * Helper method, just calls <tt>readFully(in, b, 0, b.length)</tt> |
| */ |
| public static int readFully(InputStream in, byte[] b) throws IOException { |
| return readFully(in, b, 0, b.length); |
| } |
| |
| /** |
| * <p>Same as the normal {@link InputStream#read(byte[], int, int)}, but tries to ensure |
| * that the entire len number of bytes is read.</p> |
| * |
| * <p>If the end of file is reached before any bytes are read, returns <tt>-1</tt>. If |
| * the end of the file is reached after some bytes are read, returns the |
| * number of bytes read. If the end of the file isn't reached before <tt>len</tt> |
| * bytes have been read, will return <tt>len</tt> bytes.</p> |
| * |
| * @param in the stream from which the data is read. |
| * @param b the buffer into which the data is read. |
| * @param off the start offset in array <tt>b</tt> at which the data is written. |
| * @param len the maximum number of bytes to read. |
| */ |
| public static int readFully(InputStream in, byte[] b, int off, int len) throws IOException { |
| int total = 0; |
| while (true) { |
| int got = in.read(b, off + total, len - total); |
| if (got < 0) { |
| return (total == 0) ? -1 : total; |
| } |
| total += got; |
| if (total == len) { |
| return total; |
| } |
| } |
| } |
| |
| /** |
| * Same as the normal <tt>channel.read(b)</tt>, but tries to ensure |
| * that the buffer is filled completely if possible, i.e. b.remaining() |
| * returns 0. |
| * <p> |
| * If the end of file is reached before any bytes are read, returns -1. If |
| * the end of the file is reached after some bytes are read, returns the |
| * number of bytes read. If the end of the file isn't reached before the |
| * buffer has no more remaining capacity, will return the number of bytes |
| * that were read. |
| */ |
| public static int readFully(ReadableByteChannel channel, ByteBuffer b) throws IOException { |
| int total = 0; |
| while (true) { |
| int got = channel.read(b); |
| if (got < 0) { |
| return (total == 0) ? -1 : total; |
| } |
| total += got; |
| if (total == b.capacity() || b.position() == b.capacity()) { |
| return total; |
| } |
| } |
| } |
| |
| /** |
| * Copies all the data from the given InputStream to the OutputStream. It |
| * leaves both streams open, so you will still need to close them once done. |
| */ |
| public static void copy(InputStream inp, OutputStream out) throws IOException { |
| byte[] buff = new byte[4096]; |
| int count; |
| while ((count = inp.read(buff)) != -1) { |
| if (count > 0) { |
| out.write(buff, 0, count); |
| } |
| } |
| } |
| |
| /** |
| * Calculate checksum on input data |
| */ |
| public static long calculateChecksum(byte[] data) { |
| Checksum sum = new CRC32(); |
| sum.update(data, 0, data.length); |
| return sum.getValue(); |
| } |
| |
| /** |
| * Calculate checksum on all the data read from input stream. |
| * |
| * This should be more efficient than the equivalent code |
| * {@code IOUtils.calculateChecksum(IOUtils.toByteArray(stream))} |
| */ |
| public static long calculateChecksum(InputStream stream) throws IOException { |
| Checksum sum = new CRC32(); |
| |
| byte[] buf = new byte[4096]; |
| int count; |
| while ((count = stream.read(buf)) != -1) { |
| if (count > 0) { |
| sum.update(buf, 0, count); |
| } |
| } |
| return sum.getValue(); |
| } |
| |
| |
| /** |
| * Quietly (no exceptions) close Closable resource. In case of error it will |
| * be printed to {@link IOUtils} class logger. |
| * |
| * @param closeable |
| * resource to close |
| */ |
| public static void closeQuietly( final Closeable closeable ) { |
| // no need to log a NullPointerException here |
| if(closeable == null) { |
| return; |
| } |
| |
| try { |
| closeable.close(); |
| } catch ( Exception exc ) { |
| logger.log( POILogger.ERROR, "Unable to close resource: " + exc, |
| exc ); |
| } |
| } |
| |
| /** |
| * Skips bytes from a stream. Returns -1L if EOF was hit before |
| * the end of the stream. |
| * |
| * @param in inputstream |
| * @param len length to skip |
| * @return number of bytes skipped |
| * @throws IOException on IOException |
| */ |
| public static long skipFully(InputStream in, long len) throws IOException { |
| int total = 0; |
| while (true) { |
| long got = in.skip(len-total); |
| if (got < 0) { |
| return -1L; |
| } |
| total += got; |
| if (total == len) { |
| return total; |
| } |
| } |
| } |
| } |