| /* ==================================================================== |
| 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.nio; |
| |
| import java.io.IOException; |
| import java.io.OutputStream; |
| import java.nio.ByteBuffer; |
| |
| /** |
| * A POIFS {@link DataSource} backed by a byte array. |
| */ |
| public class ByteArrayBackedDataSource extends DataSource { |
| private byte[] buffer; |
| private long size; |
| |
| public ByteArrayBackedDataSource(byte[] data, int size) { |
| this.buffer = data; |
| this.size = size; |
| } |
| public ByteArrayBackedDataSource(byte[] data) { |
| this(data, data.length); |
| } |
| |
| @Override |
| public ByteBuffer read(int length, long position) { |
| if(position >= size) { |
| throw new IndexOutOfBoundsException( |
| "Unable to read " + length + " bytes from " + |
| position + " in stream of length " + size |
| ); |
| } |
| |
| int toRead = (int)Math.min(length, size - position); |
| return ByteBuffer.wrap(buffer, (int)position, toRead); |
| } |
| |
| @Override |
| public void write(ByteBuffer src, long position) { |
| // Extend if needed |
| long endPosition = position + src.capacity(); |
| if(endPosition > buffer.length) { |
| extend(endPosition); |
| } |
| |
| // Now copy |
| src.get(buffer, (int)position, src.capacity()); |
| |
| // Update size if needed |
| if(endPosition > size) { |
| size = endPosition; |
| } |
| } |
| |
| private void extend(long length) { |
| // Consider extending by a bit more than requested |
| long difference = length - buffer.length; |
| if(difference < buffer.length*0.25) { |
| difference = (long)(buffer.length*0.25); |
| } |
| if(difference < 4096) { |
| difference = 4096; |
| } |
| |
| byte[] nb = new byte[(int)(difference+buffer.length)]; |
| System.arraycopy(buffer, 0, nb, 0, (int)size); |
| buffer = nb; |
| } |
| |
| @Override |
| public void copyTo(OutputStream stream) throws IOException { |
| stream.write(buffer, 0, (int)size); |
| } |
| |
| @Override |
| public long size() { |
| return size; |
| } |
| |
| @Override |
| public void close() { |
| buffer = null; |
| size = -1; |
| } |
| } |